Electric Motors
electric motor generator repair rebuild controls.
 

Different Types of Electric Motors

Electric motors are everywhere. I counted over 100 of them in my home, and the number keeps growing. If I were to buy a new PC, for example, I’d have to count many more. Two or three motors drive different cooling fans.

The DVD/ROM drive and DVD burner each contain four motors: tray control, spindle drive, pickup sledge drive, and laser focus servo. The hard drive has two motors, and even though floppy drives are no longer included, common peripherals such as force feedback joysticks, printers, and scanners more than make up for their loss.

For more information, see

baldor electric motor electric motor generator electric motor controller electric motor speed control industrial electric motor electric motor control bodine electric motor electric motor controls

Outside the home, trains, cranes, and electric cars contain motors that can output anything from 100 to several thousand horsepower. Stationary applications contain big motors as well. Industrial compressors, pumps, and fans are just a few examples.

Different applications also require different types of motors. A small stepper motor can position an inkjet printer head with incredible precision, but it takes a monstrous three-phase AC induction motor to drive a city water supply pump.

For almost every motor, an electronic motor drive circuit controls its speed and torque. The electronics that control the print head motor and the water pump motor are as different as the motors themselves. A $.50 8-bit microcontroller can drive a stepper motor, while the current drive comprises a few surface-mounted metal-oxide semiconductor field-effect transistors (MOSFETs).

On a water pump motor, the fat copper rails connecting it to the power stage hint at large electric currents. The power stage is based around gigantic insulated gate bipolar transistor (IGBT) transistors that alternate the direction of the current through the motor’s three-phase windings.

Serious Computing Power Needed

The computing horsepower required to efficiently control pump motors is almost as impressive as the motor itself – at least to an electrical engineer. At the heart of the motor drive sits a high-performance CPU, and a busy one at that.

For additional information, refer to:

how does an electric motor work variable speed electric motor electric motor warehouse electric motor starters electric motor repair electric motor repairs electric motor drives electric motor drive fasco electric motor ao smith electric motor linear electric motor electric motor maintenance electric motor rebuild electric motor frame electric motor brush brushless electric motor electric motor starter us electric motor electric motor brake emerson electric motor electric motor brushes electric golf cart motor electric motor rebuilding electric seat motor electric motor price electric motor design electric motor testing electric motor capacitors hybrid electric motor buy electric motor electric motor cleaner 5 hp electric motor electric motor supply electric motor winding universal electric motor dc electric motor small electric motor ac electric motor

Among its many tasks is generating the three 120-degree out-of-phase sine waves on which AC induction motors thrive. It varies the duty cycle of the drive currents at high frequency, and the inductive load “sees” the waveform as a smooth sine wave. This is pulse width modulation (PWM).

The sine waves, amplified many times by the power stage, make the motor spin. The CPU controls the speed and torque of the motor by varying the frequency and amplitude of the sine wave, respectively. However, as in an automobile, holding the accelerator in a fixed position doesn’t guarantee travel at a constant speed. This is why some clever engineers invented the cruise control, and also why equally clever engineers came up with electronic motor controls.

Throw Some Math in There

In simple terms, the CPU controls the speed and torque of the motor this way:

Read speed and torque values

Compare with desired settings

Calculate increments or decrements

Adjust speed and torque using values from #3

Repeat series from #1

The most commonly used method to calculate the adjustments in step #3 is known as PID – proportional integration and derivation. PID comprises a series of computations that take the differences between desired and current operation as inputs and spit out suitable adjustments proportional to those differences – small adjustments for small deviations, bigger changes if the motor is really off-kilter.

You can’t just add or subtract the entire difference, because it takes several control loop iterations for the motor to react to a change in input. Such an approach would lead to instability, with wildly oscillating values.

The motor drive measures the speed of the motor by decoding signals from an optical or magnetic encoder on the motor’s drive shaft. A state machine known as quadrature encoder interface (QEI) decodes these signals. Measuring phase currents at certain points in the PWM cycle gives you the torque.

You can then feed other parameters to the control algorithm, such as voltage and current waveform profiles. If you take the latter and throw complex math at it, such as an algorithm bearing the “Star Trek”-like name of flux vector control, you can predict the motor’s behavior very accurately without an opto-mechanical or magnetic interface.

See also:

electric motor shop electric motor sales electric fan motor electric motor mount 10 hp electric motor electric wheel motor electric motor manufacturers 2 hp electric motor electric motor power electric motor bearings 1 2 hp electric motor electric motor wire electric motor scooters electric motor parts electric motor cooling electric motor capacitor electric motor rewind 1 hp electric motor electric motor rewinding electric motor service 2hp electric motor electric motor cycle reliance electric motor ohio electric motor electric motor electric vehicle motor 3 hp electric motor used electric motor electric motor company electric motor bearing electric motor hp 20 hp electric motor electric motor troubleshooting motor city electric electric motor calculator electric motor model electric motor specs miniature electric motor electric motor mounts dayton electric motor general electric motor ge electric motor electric motor rpm 5hp electric motor electric motor shaft 12 volt electric motor general electric ac motor electric motor cycles surplus electric motor electric gear motor electric motor windings electric boat motor how to build an electric motor electric car motor 12v electric motor electric trolling motor mini electric motor how to make an electric motor hobby electric motor make an electric motor electric motor oil electric outboard motor build an electric motor single phase electric motor the electric motor build electric motor electric clock motor electric motor kits toshiba electric motor electric motor weight westinghouse electric motor electric motor horsepower electric motor kit franklin electric motor high torque electric motor large electric motor electric motor pulley building an electric motor toy electric motor electric motor project electric motor science project electric motor noise magnetek universal electric motor beakman's electric motor electric motor efficiency 3 phase electric motor electric motor frame sizes parts of an electric motor electric motor grease electric bike motor electric motor schematic

This is useful when controlling smaller motors, where gadgets like shaft encoders take up too much space and cost more than the incremental CPU power to eliminate them.

Most industrial motor drives are also connected to some kind of network, so when you add the computational powers required to run a TCP/IP or DeviceNET stack on top of everything, performance requirements can reach as much as several hundred MIPS – if you solve your embedded computing needs with brute force. Like hunting sparrows with a rocket launcher, it works, but there are more elegant approaches to meeting performance requirements.

Look Ma, No Brushes

The AC induction motor is generally considered the workhorse of all industrial motor types. Another popular motor for high-performance applications is the brushless DC motor (BLDC), also known as the permanent magnet AC motor.

The apparent confusion arises from the fact that it is built on the principles of a DC motor but operates from an alternating current. The BLDC motor doesn’t need a sine wave, but the motor drive must know its exact rotational position at any time, thus calling for a different position encoding/decoding mechanism than AC induction motors. When it comes to controlling currents and voltages, PWMs are still the name of the game.

Doing It My Way

Because you cannot build a high-performance motor drive without PWMs, many embedded processors and microcontrollers come with PWMs built-in. These PWMs are the result of long discussions between the chip vendor’s marketing and engineering departments. It’s a battle between customer requirements on one side and die size estimates, design time, and testability on the other. The resulting design is a compromise between what the “average” customer wants and what can be done within the confines of cost and time-to-market requirements.

A Square PWM in a Square Hole

PWMs come with different features and settings: varying resolution and speed, edge-aligned versus center-aligned, dead time generation, and symmetrical outputs. Most on-chip modules offer software configurations of these parameters, but more often than not, off-the-shelf modules will not meet your exact requirements. Even if they did, that technology would also be available to your competitors. Using a standard module often requires limiting adaptations to the power stage and control software.

A clever motor drive design requires that software, power stage, and PWMs work together in perfect unison. In other words, you need full freedom in designing all three, which effectively rules out on-chip PWMs.

FPGAs to the Rescue

Custom PWMs = custom logic = FPGAs. With an FPGA, you can also do custom QEI interfaces, an ADC interface, safety circuitry, and timer arrays, all designed exactly the way you want them.

The Next Step: Embedded Integration

The traditional high-performance AC induction motor drive comprises an FPGA and an embedded processor, as shown in Figure 1. This configuration works well, except that the control loop traverses the bus between the two components twice. Because this bus is often shared with other system functions, performance is indeterministic and easily becomes an unnecessary bottleneck in loop response time.

More Info can be found about:

magnetek electric motor
electric motor cross reference
make electric motor
induction electric motor
electric motor cars
electric motor torque
200 hp electric motor
electric motor diagram
electric motor manufacturer
century electric motor
100 hp electric motor
electric motor wiring
electric motor frame size
electric motor plans
global electric motor
electric motor bikes
weg electric motor
siemens electric motor

Xilinx® embedded technology allows you to bring the embedded processor onto the FPGA. The benefits of this approach go beyond fewer components, smaller size, and fewer suppliers. It also improves both performance and design time.

Co-Processor Interface

It does not matter whether you choose the 32-bit MicroBlaze™ soft-core processor or hard-coded PowerPC™ 405 processor. Both offer some unique benefits through circuitry dedicated to interfacing with on-chip peripherals in the FPGA fabric. Figure 2 shows some design examples in which all control loop data travels to and from the CPU over a dedicated, deterministic link that is not shared with any other resources.

Eliminating bottlenecks in a design is like peeling away the layers of an onion. You design around one hurdle, and the next one reveals itself immediately. Now that an important hardware pipe has been effectively unclogged, you should not be surprised to see a potential for improvements in your software. Figure 3 shows the software analyzer that comes packaged with the Xilinx Embedded Development Kit (EDK). This tool could prove exceptionally helpful in identifying resource-consuming functions. Motor control software, like anything else, is likely to have its share.

Intelligent Versus Brute Force

I have already mentioned the brute-force approach to designing embedded systems. FPGA processors with a co-processing interface effectively put an end to throwing raw MIPS at any performance challenge. A carefully designed hardware/software mix can reduce CPU performance requirements by several orders of magnitude.

Typical software bottlenecks in a drive are floating-point math functions, DSP functions, and of course, the PID function. As the designer, you should define the optimum mix between hardware and software modules. The FPGA gives you full freedom to balance this any way you want.

A New World of Debugging

The traditional design split of an embedded processor plugged onto an FPGA can be a nightmare to debug. With two different sets of debugging tools probing two different chips, visibility of interaction between the two is extremely limited. The Xilinx ChipScope™ Pro analyzer lets you debug software and hardware interaction like never before. You can set the debugger to trigger when the base counter inside the PWM reaches 0x3FF and observe what code lines were executed within a 50 ìs window around that point – without halting execution. Or set the debugger to trigger on each Phase X zero crossing in the sine table and observe the resulting PWM waveform over the next 5 ms.

With full visibility of any chain of events within the system, you can track down even the most elusive bugs in minimum time.

Motor Control Components Ready to Go

As much as we at Xilinx recognize the fact that you are the drive design experts, we do provide a few bits and pieces to give you some ideas of what’s possible with embedded processing on FPGAs.

Our reference design, “Spinning Wheels,” contains complete implementations of one BLCD and one AC induction motor drive. The IP of the solution is openly available as VHDL source code:

BLDC drive unit

Hall effect BLCD decoder

AC induction drive unit

QEI

Check these for more information:

electric bicycle motor
johnson electric motor
electric motor specifications
electric motor theory
electric wiper motor
lincoln electric motor
rc electric motor
rc car electric motor
electric hub motor
basic electric motor
electric motor works
simple electric motor
electric motor projects
electric motor wiring diagram
homemade electric motor

The solution comes packaged with reference designs that include MicroBlaze integration with C code examples, tutorials, application notes, and simulation test benches if you don’t have a power stage and a motor handy at all times.

Take a look at the blocks and play with them to get a feeling for what’s possible. Once you have pieced them together, feel free to sprinkle the design with an FPU and a CAN2.0B interface, or whatever it takes to make it the perfect drive.

Motor control design is tough work. The quest for smarter, faster, and more power-efficient designs imposes an enormous strain on software and hardware engineers. By adopting FPGAs with on-chip embedded processors, you are free to implement the creative design ideas needed to pull ahead of your competitors. With full flexibility in PWM design and control over the hardware/software split in the control functions, the possibilities are endless.

Carmakers are taking increasingly complicated measures to protect the vehicle owner's investment. Understanding antitheft technology can save service time on vehicles.

If ever there was a work in progress, its automotive security systems. GM is already on its fourth-generation system since it first introduced VATS (Vehicle Anti-Theft System) in 1986. New antitheft systems from all of the major brands in the U.S., Japan and Europe seem to come under attack as soon as they're introduced.

Last year, almost $8 billion worth of cars were stolen in the U.S., and only 65% of them were recovered. Canada alone thinks that some of its 20,000 stolen vehicles were exported last year.

In the meantime, these systems have an enormous effect on the automotive service industry. You don't even have to have your vehicle stolen to be affected. Lose your keys? Recently, a Ford-owning friend forked over $108 to have a key and fob replaced. Own an expensive European make? Replacement of the key and the security computer could cost you thousands of dollars. Now there's yet a new generation of these systems on your doorstep.

Let's take a look at where we are and what's coming while we guess how long it will take the bad guys to circumvent this latest generation technology.

GMs antitheft systems have been out there the longest and are fairly representative of the types of antitheft systems used on other makes. Originally named VATS, this is a good example of a first-generation system. The key uses an embedded resistor. When the key is inserted into the lock, two fine wires contact the resistor. The VATS module measures this resistance and compares it to the stored value. If they match, the vehicle is allowed to start. If they don't, a delay of up to 10 minutes is required before another attempt can be made to start the car.

See more on:

global electric motor cars
electric motor types
how an electric motor works
history of the electric motor
3 4 hp electric motor
3 phase 4 pole electric motor
ajax electric motor
electric motor basics
electric motor conversion
electric motor corp
electric motor data
electric motor dimensions
electric motor history
electric motor repair parts
electric motor wiring diagrams

In 1996, VATS was superceded in favor of the Passlock system. This system works similarly to VATS, except the resistor has been moved into the ignition switch. The Passlock II system actually had two variants, but essentially was still a resistorbased system.

Passlock III, Passlock III+ and Ford's securilok system, among others, use transponder-based radio frequency identification (RFID) technology. At its most basic level, this is a wireless radio link used to identify objects or people.

When a transponder enters a read zone, its data is captured by the reader and then passed along to a computer or other logic controller for action. It's much the same as the technology that identifies a runner in a marathon, a vehicle passing through a tollbooth without having to slow down or the plastic card that lets you through the security gate at work.

For automotive applications, key-based immobilizer systems consist of four main components. The heart of the system is the transponder, which is a batteryless chip. To operate the chip, it has to be supplied power from an external source. The transceiver generates a high-frequency (134.2kHz) magnetic field, which radiates from an antenna coil. The energy activates the transponder, which sends a data stream in the form of an RF-modulated signal. This signal is demodulated by the transceiver and then passed to the controller for processing.

There are two different types of transponder systems-full-duplex and half-duplex. In a fullduplex system, tire energy for the transponder and the data signal generated by the transponder are transmitted at the same time. In a half-duplex system, they're sent separately. The transponder stores the energy it receives in a capacitor. As soon as the transmitter is turned off, the transponder uses that stored energy to transmit the data. The two types of systems have different effective ranges and cost factors, but the degree of security is die same.

There are some evildoers out there with the motivation to bypass both resistor-based and transponder-based systems. But among the legitimate bypassers are the makers of remote engine starting systems. A driver would be foolish to leave the key in the ignition. So at least for the amount of time needed to start a vehicle, the modules diese companies sell, along with the remote starter, bypass the antitheft systems.

The next generation of systems coming to market offer much higher levels of security. They use cryptographic techniques to ensure the codes cannot be stolen or bypassed.

The need for this type of security got its start with the garage door industry. Early garage door openers basically transmitted a unique ID code to make sure it was your garage door you opened and not your neighbors. As with any signal being broadcast, those people with the right equipment could receive the signal and record it. Later, when you're away, the signal could be re-sent, opening your home to would-be intruders. How much of this really went on is unknown, of course, but these "code grabbers" were widely talked about as a threat to home security.

The technology developed to defeat this possibility is called rotting code technology. The remote and the receiver keep internal counters that begin by being synchronized with each other. Each time the remote is used, the stored code number is increased by a specific amount. When the user pushes the button on the remote, the current value of the counter is transmitted, along with the fixed ID number. The door opens only if both numbers match.

AC motor

AC motor drives interface controllers to AC motors. They match the control signals (voltage and power levels) as well as the signal type (analog or digital). They also provide power conversion, amplification, and the sequencing of waveform signals. AC motor drives are used with many types of AC motors. Induction motors induce current into the rotor windings without any physical connection to the stator windings.

They are suitable for many different environments and are capable of providing considerable power as well as variable speed control. Synchronous motors are no-slip devices that operate at constant speed up to full load. Subcategories include reluctance motors and permanent magnet devices such as AC servomotors. Many AC servomotors use brushless commutation with feedback provided by Hall effect sensors.

Pole changing motors use pole number control, a method for changing the number of poles on the primary winding. Vector drive motors provide independent control of both the voltage and frequency, resulting in low-speed torque outputs that approach those of DC motors. In some designs, encoders or resolvers are used to provide feedback about position and speed. Linear motors generate force in only the direction of travel. Common technologies include moving coil, moving magnet, and switched reluctance designs.

Selecting AC motor drives requires an analysis of application categories. Multi-axis controllers are used to control and monitor multiple, independent axes of motion. Motor speed controllers are application-specific and used to control machines such as conveyors. Robotic motion controllers use digital motion control hardware and software for the coordinated multi-axis control of industrial robots and robotic systems.

Servo amplifiers are electronic modules that convert low level analog command signals to high power voltages and currents. Inverter drives convert AC power inputs to DC outputs. High frequency drives supply power to AC motors at frequencies that are considerably higher than those used in standard-power applications. Regenerative drives support motor braking. Variable speed drives support speed control and adjustment. AC motor drives that use microcontrollers, silicon controlled rectifiers (SCR), digital signal processors (DSP), and pulse width modulation (PWM) are also available.

More information is available on:

etek electric motor
first electric motor
make a electric motor
precision electric motor
small electric motor repair
the first electric motor
three phase electric motor
vulcan electric r c twin motor
vulcan electric r c twin motor glider

AC motor drives differ in terms of electrical ratings, operating parameters, configurations, and features. Electrical ratings include maximum output voltage, rated power, continuous output current, peak output current, AC supply voltage, and DC supply voltage. AC motor drives use either single-phase or three-phase inputs at 50, 60, or 400 Hz. Operating parameters include specifications for setup and control. Some AC motor drives have manual controls such as knobs, DIP switches, jumpers or potentiometers. Others include a joystick, digital control panel, computer interface, or slots for PCMCIA cards. Control programs can be stored on removeable, nonvolatile storage media. Hand held devices are designed to be programmed remotely. Wireless and web-enabled controls are also available. Configurations for AC motor drives include several mounting styles. Most devices mount on a chassis, DIN rail, panel, rack, wall, or printed circuit board (PCB). Standalone devices and integrated circuit (IC) chips that mount on PCBs are also available. Features for AC motor drives include soft starting; dynamic, injection, or regenerative braking; brake outputs or auxiliary inputs/outputs (I/O); auto-tuning, self-diagnostics, and status monitoring; and alarms for conditions such as overvoltage.

Computer-based AC motor drives use many different types of buses and communication standards. Bus types include advanced technology attachment (ATA), peripheral component interconnect (PCI), integrated drive electronics (IDE), industry standard architecture (ISA), general-purpose interface bus (GPIB), universal serial bus (USB), and VersaModule Eurocard bus (VMEbus). Communications standards include ARCNET, AS-i, Beckhoff I/O, CANbus, CANopen, DeviceNet, Ethernet, small computer systems interface (SCSI), and smart distributed system (SDS). Many serial and parallel interfaces are also available

Design of Electric Motors, Generators and Drive Systems

This course focuses on the analysis and design of electric motors, generators, and drive systems. Special emphasis will be placed on the design of machines for electric drives. This course will focus on fundamentals by using commercially available software for mathematical analysis (MATLAB) in the context of design. Extensive "hands-on" exposure will be provided through computer based laboratory exercises and through the opportunity to construct and test an actual power electronic drive for a test motor in our laboratory.

The construction of aggressive, high-performance motor drives requires a detailed understanding of machine characteristics and associated interactions with power electronic drives. The successful application of modern control techniques, such as field-oriented control, depends critically on an intimate knowledge of machine parameters and characteristics. Lower shaft horsepower drives, for example, may exhibit a relatively speedy decay of electrical transients in comparision to mechanical transient settling times. In very large drives, the situation can be reversed. Even for drives employing machines of the same general type, appropriate analytical approximations, thermal management and modeling, control techniques, and transient performance and disturbance rejection for low and for high power drives may therefore be very different. Computer-based tools for estimating machine parameters and performance can remarkably speed a designer's understanding of when different control and machine design assumptions are applicable, and how gracefully these assumptions fail as performance limits are approached. Hands-on experiments will give the opportunity to compare analytical results with real motor/drive systems in the laboratory.

In this course, fundamental principles of energy conversion, applicable to all types of electric machinery, are first reviewed to provide analytical foundations for understanding all types of drives. The specific principals of the basic machine types, including synchronous, induction and variable reluctance machines, are then introduced. Extensive use of computer-based analysis tools will be made as the major classes of machines and their physical basis for operation are reviewed. Next, control strategies for the different machine types will be discussed, all with extensive use of computer-based simulation tools. Power electronic circuits required to drive the machines will be considered and a real drive circuit will be constructed, de-bugged and tested by each participant. Throughout the course, performance considerations, trade-offs, and different design approaches will be presented. Access to computer facilities, analysis routines and laboratory hardware facilities will be provided for practice machine analysis design and test.

Required Background

A basic knowledge of electric circuit analysis and working familiarity with principles of electromagnetism is assumed.

Program Description

Lectures will be given in the morning of each day, Monday through Friday, of the program. In the afternoons students will work with the instructors in a computer facility to explore and develop design routines for electric drives. Registrants will receive course notes, reprints of references and a suite of programs written in MATLAB for assisting in the design of electric machines.

Learning Objectives

Describe fundamental principles of energy conversion which are the analytical foundations for understanding all types of drives.

Identify the principals of the basic machine types, including synchronous, induction and variable reluctance machines.

Evaluate the use of computer-based analysis tools to review the major classes of machines and their physical basis for operation.

Describe control strategies for the different machine types, following the use of computer-based simulation tools.

Examine very high performance machine designs, such as extremely high speed drives.

Analyze performance considerations, trade-offs, and different design approaches.

Evaluate the hands-on use of machine analysis and design, using computer facilities and analysis routines.

Topics

Elements of energy conversion: energy, co-energy, force and torque as derivatives of energy, field- based force calculations.

Energy conversion in electric machines: force and shear density, machine power density and efficiency.

Review of the principles of the basic machines types: synchronous, induction, variable reluctance.

Introduction to and exercises in the use of MATLAB.

Induction machines in some depth: reduction to an equivalent circuit and calculation of the elements of the circuit.

Performance evaluation of induction machines.

Field-oriented control of induction machines.

Permanent magnet machines: review of basics, principles of energy conversion and design fundamentals.

Control strategies for PM machines: torque/speed limitations, taking advantage of negative saliency, elements of field oriented control.

Unusual machine designs

THANK YOU

Bookmark pages
Bookmark this page if YOU like it *new*
 
AddThis Social Bookmark ButtonBookmark


When you find your suitable answer for your questions, or benefit from the page, I sincerely hope that you can kindly put a backlink to our page in order to spead the word and the site to more people who seek for tips to generate more benefits in life.

Your kind action for putting a backlink is a great motivation for us.

I am asking for your help to make this page (which I last modified on Tuesday February 12, 2008 ) a success. If each of you who read this could forward the link to two others, and they forward the link to two others, we will have over 1,000,000 readers in only 20 iterations! Believe in the power of word-of-mouth and spread the word...




° LARGEST U.S. CITIES: New York City,New York|Los Angeles,California |Chicago,Illinois |HoustonTexas |Philadelphia,Pennsylvania |Phoenix,Arizona |San Diego,California |San Antonio,Texas |Dallas,Texas |San Jose,California |Detroit,Michigan |IndianapolisIndiana |Jacksonville,Florida |San Francisco,California |Columbus,Ohio |Austin,Texas |Memphis,Tennessee |BaltimoreMaryland |Fort Worth,Texas |Charlotte,North Carolina |El Paso,Texas |BostonMassachusetts |WashingtonDistrict of Columbia |Milwaukee,Wisconsin |Seattle,Washington |Denver,Colorado |Louisville-Kentucky |Nashville-Tennessee |Las Vegas,Nevada |Portland,Oregon |Oklahoma City Oklahoma |Tucson,Arizona |Albuquerque,New Mexico |AtlantaGeorgia |Long Beach,California |Fresno,California |Sacramento,California |New OrleansLouisiana |Cleveland,Ohio |Kansas City,Missouri |Mesa,Arizona |Virginia Beach Virginia |Omaha,Nebraska |Oakland,California |Miami,Florida |Tulsa,Oklahoma |HonoluluHawaii |Minneapolis,Minnesota |Colorado Springs Colorado |Arlington,Texas |Wichita,Kansas |St. LouisMissouri |Raleigh,North Carolina |Santa Ana,California |Anaheim,California |CincinnatiOhio |Tampa,Florida |Pittsburgh,Pennsylvania |Toledo,Ohio |Aurora,Colorado |Bakersfield,California |Riverside,California |Stockton,California |Corpus Christi Texas |Newark,New Jersey |Buffalo,New York |St. Paul,Minnesota |Anchorage,Alaska |Lexington,Kentucky |Plano,Texas |St. Petersburg,Florida |Jersey City,New Jersey |Glendale,Arizona |Lincoln,Nebraska |Chandler,Arizona |Henderson,Nevada |Greensboro,North Carolina |Norfolk,Virginia |Birmingham,Alabama |Scottsdale,Arizona |Fort Wayne,Indiana |Baton RougeLouisiana |Madison,Wisconsin |Hialeah,Florida |Chesapeake,Virginia |Garland,Texas |Orlando,Florida |Rochester,New York |Akron,Ohio |Chula Vista,California |Fremont,California |Lubbock,Texas |Laredo,Texas |Modesto,California |Durham,North Carolina |Reno,Nevada |Montgomery,Alabama |Glendale,California |ArlingtonVirginia, |Shreveport,Louisiana |San Bernardino California |Spokane,Washington |Yonkers,New York |Tacoma,Washington |Huntington Beach,California |Des Moines,Iowa |Grand Rapids,Michigan |Richmond,Virginia |Winston-Salem,North Carolina |Irving,Texas |Boise City,Idaho |Mobile,Alabama |Augusta-Georgia |Irvine,California |Columbus,Georgia |Little Rock,Arkansas |Oxnard,California |Amarillo,Texas |Knoxville,Tennessee |Newport News,Virginia |Moreno Valley,California |Salt Lake City,Utah |Jackson,Mississippi |Providence,Rhode Island |North Las Vegas,Nevada |Gilbert,Arizona |Ontario,California |Worcester,Massachusetts |Rancho Cucamonga,California |Santa Clarita,California |Aurora,Illinois |Brownsville,Texas $|Fort Lauderdale,Florida |Huntsville,Alabama |Oceanside,California |Garden Grove,California |Overland Park,Kansas |Fontana,California |Tempe,Arizona |Dayton,Ohio |Tallahassee,Florida |Vancouver,Washington |Chattanooga,Tennessee |Pomona,California |Santa Rosa,California |Rockford,Illinois $|Springfield,Massachusetts |Pembroke Pines,Florida |Springfield,Missouri |Paterson,New Jersey |Corona,California |Salem,Oregon |Salinas,California |Hollywood,Florida |Hampton,Virginia |Eugene,Oregon |Grand Prairie,Texas |Kansas City,Kansas |Pasadena,Texas |Pasadena,California |Torrance,California |Syracuse,New York$ |Naperville,Illinois |Lakewood,Colorado |Hayward,California |Cape Coral,Florida |Sioux Falls,South Dakota |Bridgeport,Connecticut |Peoria,Arizona |AlexandriaVirginia |Joliet,Illinois |Warren,Michigan |Orange,California |Palmdale,California |Escondido,California |Lancaster,California |Fullerton,California |Port St. Lucie,Florida |Fayetteville,North Carolina |Mesquite,Texas |Sunnyvale,California |Coral Springs,Florida |Savannah,Georgia |Sterling Heights,Michigan |Fort Collins,Colorado |Elizabeth,New Jersey |New Haven,Connecticut |Hartford,Connecticut |Thousand Oaks,California |McAllen,Texas |Concord,California |Cedar Rapids,Iowa |El Monte,California |Topeka,Kansas |Waco,Texas |Stamford,Connecticut $|West Valley CityUtah |Carrollton,Texas |Simi Valley,California |Flint,Michigan |Vallejo,California |Bellevue,Washington |Columbia,South Carolina |Evansville,Indiana |Springfield,Illinois |Lansing,Michigan |ProvoUtah |Abilene,Texas |Inglewood,California |Ann Arbor,Michigan |Clarksville,Tennessee |Peoria,Illinois |Elk Grove,California |Lafayette,Louisiana |Beaumont,Texas |Olathe,Kansas |Independence,Missouri |Costa Mesa,California |Downey,California |Manchester,New Hampshire |Clearwater,Florida |Visalia,California |West Covina,California |Gainesville,Florida |Waterbury,Connecticut |Allentown,Pennsylvania |Charleston,South Carolina |Miramar,Florida |Cary,North Carolina |Roseville,California |Norwalk,California |Santa Clara,California |South Bend,Indiana |Thornton,Colorado |Lowell,Massachusetts |Westminster,Colorado |Fairfield,California |Pompano Beach,Florida |Denton,Texas |Burbank,California |San Buenaventura California |Arvada,Colorado |Pueblo,Colorado |Athens,Georgia |Erie,Pennsylvania |Richmond,California |Norman,Oklahoma |Cambridge,Massachusetts |Green Bay,Wisconsin |Berkeley,California |Antioch,California |Daly City,California |Killeen,Texas |Portsmouth,Virginia| OTHER INFORMATION: By owner rent Buy Now. equipment sale price cost dollars cents refund cash paypal Buy Now. mastercard discover american express visa first second quality. $ closeout distressed discount We broker, buy, sale price Buy Now. sell and trade industrial and civilian materials and products. We help sell.General Supply,$ Freight Salvage Surplus, Closeouts, Warehouse cleanouts. sale price Repossessions, Junk, Insurance Salvage, Buy Now. Disposable Merchandise, Industrial Surplus, Medical $ Surplus, Storage Rental Bins, Storage Trailers, used Equipment, Used Freight sale price Vans, $ Building Materials, uy Now. Factory Seconds, Discontinued Merchandise, Garage Clean Outs, Factory Clean Outs, Shipping Containers, Out of Business Sales, merchandise. Buy Now sale $ price Merchandise Returns, Retail closeouts, storage buildings, donations, Garage Cleanouts, Sale Leftovers, Used. Factory rejects, Antiques, Collectibles, Distressed Merchandise, Insurance Claims, sale price Insured Settlements, Refunds.

There are about 10,000 words on this page.

Find this page fast. Type 1srotom in a searchbox . (that's "motors1" spelled backwards)

AddThis Social Bookmark Button

NOTE: FULL PROFITABILITY WILL RISE WITH THE PROPER EQUIPMENT! CAN BE SENT AT DISCOUNT PRICES. YOU CAN BUY NOW OR RENT. EQUIPMENT IS ON SALE WITH A PRICE COST OF LOW DOLLARS AND CENTS. REFUND IS OFTEN IN CASH IF NOT SATISFIED. IF YOU DECIDE TO BUILD YOUR OWN (DIY) YOU CAN OFTEN UTILIZE LEFTOVERS FROM FACTORY SECONDS, SURPLUS , DISCONTINUED MERCHANDISE, GARAGE CLEAN OUTS, WAREHOUSE CLEANOUT, RETAIL CLOSEOUTS, ITEMS FROM FACTORY REJECTS, OUT OF BUSINESS SALES & FACTORY CLEAN OUTS. FINALLY, DON'T OVERLOOK CLOSEOUTS! WHEN BUYING ONLINE, PAYPAL, MASTERCARD, DISCOVER, AMERICAN EXPRESS, AND VISA ARE ALMOST ALWAYS ACCEPTED. RENTALS OF FIRST AND SECOND QUALITY ARE POSSIBLE. SPECIAL PRICES ALWAYS APPEAR AT CLOSEOUT AND DISTRESSED SALES. WE DO NOT BROKER OR BUY THESE ITEMS FOR RESALE. ORDINARILY, THE SALE PRICE IS FINAL FOR USED EQUIPMENT, REPOSSESSIONS, JUNK, INSURANCE SALVAGE OR FREIGHT SALVAGE. DISTRESSED MERCHANDISE CAN BE A GOOD SOURCE OF GENERAL SUPPLY FOR INDUSTRIAL MATERIALS AND PRODUCTS. AGAIN, BUY NOW, BUY NOW, BUY NOW. THE SALE PRICE MAY NEVER BE LOWER. SAVE $ $ $ $ $ $ $ $ $ $.

GET MORE OUT OF LIFE

Leisure/Culture

ARTS

° Nancy Ajram -- Lebanese Music Singer of Arabic Songs -- THIS MUSIC SIZZLES ! Show me

° Eddie Murphy What We Did Not Know About Him Show me

Technology

°

° Spy Cameras -- Indoor and Outdoor Cameras are NOW Easy to Install for Home or Business! Show me

° iPhone - A Review of this Great PDA Cell Phone Product With Games and Gadgets: This Mobile Wireless Cellular Product Should Compare in Price to the Samsung Mobile Camera Phone !!! Show me

° Why Your Headphones Benefit From Noise and Vibration Reduction Technologies Show me

° Hydraulic and Electric Scissor Lifts are For Sale -- Used and New Show me

° Portable, Industrial, and Siphon Sandblasting Equipment (Cabinets, Sandblasters, Nozzles, Sand, How to Make, etc) -- Used and New Show me

° Diesel Engines And Great Fuel Economy -- the SECRET is Fuel Injectors Show me

° Why Are They So Important? Air Compressors…heavy duty industrial air compressors, medical air compressors, and portable dental air compressors of both types— electric air compressors and gas powered air compressors. Show me

° Plastic Pallets Beat Wooden Pallets! But Aluminum Metal Pallets -- Beat ALL with Stackers Show me

° Why Hidden Benefits in Corrugated Cardboard Pallets Are Saving Us Hundreds of $1000's of Dollars Show me

° Cranes -- Different Kinds and How They Work Show me

° Electric Motors Rule! See why Electric Motor Controls and Generator Rebuilds are the Way to Go! Show me

° Construction License -- Your Life Changes When You Get One Show me

° Bronze Plaques and Memorial Bronze Statues Gifts Sculptures and Jewelry Are The Perfect Gift and Hobby Show me

° Spray Foam Insulation Residential and Commercial Show me

Business/Law

° Best Mortgage Information Available Refinancing Mortgage…Low Interest Loan Rate!!!. Show me

° Detect IT !!! Those Who Know How To Make Counterfeit Money -- CAN'T DEAL WITH THIS Show me

° Get Yourself Some Internet Advertising Income…Simply. Show me

° Make Money Partnering With Online Merchants Show me

° Increase Your Organization's Productivity With Dispersed Work Teams Collaborate & Do Virtual Collaboration With Collaborative Learning in Global Groups!!! Show me

°Brian Nelson Consulting .com Business and Organization Consulting. Making a Difference in the world. Minimum Fee $1,000 $ 110 % Guarantee Show me

° NelsonIdeas.com Creative problem solving Minimum Retainer Fee $1,000 Show me

° Mortgage Marketing Act Smarter, Be Happier Show me

Computers

°About Web Identity Theft Show me

° Web Hosting & Domain Names -- Webmasters Love This One!!! Show me

° It's Free. Save Time! Streamline Your Web Activities With Server Side Includes (SSI) Show me

Health

° There's Still Hope With Liver Cancer Show me

° Breast Cancer Facts and statistics about diet, advanced and inflammatory breast cancer prevention, treatment, and symptoms -- support early detection! Show me

° Toxic Black Mold And Mildew -- Test In House Or Home-- For Removal / Remediation / Abatement. It’s a business that can literally REMOVE YOUR ALLERGY OR ILLNESS ! Show me

° Feel electrified with energy! Vitamins and Minerals Show me

° Social Anxiety Disorder, Phobias and Depression - Stop the Symptoms, Cure, and Get Relief! DO IT NOW Show me

° Sleep Better Tonight Show me

° Get Your Youthfulness Back -- This HGH Way! Show me

° Asbestos and Mesothelioma -- Bad, bad, bad Show me

Viral Infections

°Hepatitis C. Lots of folks have it BUT DON'T KNOW IT-- Treatments, Therapies, and potential cures -- Show me

Home

° Biometrics for Your Security! You Can't Just Guess! The New Trend: Fingerprint, Retina, Voice, Facial, Hand, and Iris Scanners and Identification-Recognition Systems! Show me

° Safeguard Your Assets Term Life Insurance…Simply. Show me

° Stop Foreclosure Show me

° House Sitter Wanted? What You Need to Know Show me

Pets

° Adopt a boxer! Beautiful Boxer…See Boxer Pictures. Show me

° Dog Arthritis -- Pain Relief First ... then a Cure Show me

° "Who Else Wants to Own the Happiest and Healthiest Pomeranian on the Block?" Show me

° Dog - Cat/Diarrhea & Constipation when your dogs or cats are sick Show me °

Sports/Recreation

° Tennis, Anyone? Serena Williams Crunk! Show me

° Fun! Excitement! The Gumball3000 Rally. Cars F-A-S-T! Show me

° Virtual Golf, Indoor Golf Simulation and Simulators - World Class Indoor Golf! Show me

° The Secret Colombia Paradise! Show me

° What's New About Weightlifting And Running Show me

° Skydiving, Freefall, and Parachuting Off Of Bridges (BASE). Show me

° Party Tent City.com Party Tents, Awnings, Fire& Flame Retardant Tarps Canopies Camping Canopy, Clear Window Tarpaulins, Wedding & Church Revival Tents Show me

Reference

° Bible Pronunciation-HEAR AUDIO-of hard-to-pronounce Biblical names, words, and places Show me °

Regional

° AFRICA -- It's Time To Win Against AIDS! Show me

° Aztec -- They Sacrificed Over 19,000 People A Year! Show me

° Travel FREE with Education Grants -- AMERICORPS Show me °

Science

° Snakes-- Deadliest Of The Deadly: Information And FAQs On Venomous Snakes And Lizards Show me

° Do You Understand Your Cell Phone? The Cell Phone Expert Shows How Your Cell Phone Works PLUS New Info On Digital Phones and Wireless Show me°

Industry

° Make Floors Dazzle with Concrete Floor Grinders Show me

° Electric Motors -- Over 100 of them in your home! Show me

Society

° "Fashions For Women" Show me ° Skin That Is Soft And Smooth -- Yours? Show me

° Handbags and Purses -- Be In Style Wherever You Take Your Handbag! Show me

° HomeRemediesForDryHands.com, is the UPDATED site of the "Hands That Are Rough" that follows this... Show me

° Hands That Are Rough, Dry, Chapped, or Otherwise Diseased Can Now Be Silky! (Previous Version) ! Show me

° Your Best Life Now! What's The Story of Joel Osteen? Show me

° 2008 China Olympics In Beijing BOYCOTTED FOR HUMAN RIGHTS VIOLATIONS !!! Show me

_

Dr. Kottley is a specialist in electric machinery and electric power systems engineering. He has participated in broadly based research and development programs in several related areas, including superconducting electric machinery, large machinery for ship propulsion, monitoring of electric power systems and equipment, magnetic bearings and magnetic levitation and design of electric machinery. In addition to core subjects in electrical engineering and computer science, his teaching activities include graduate and undergraduate subjects in electric machinery and electric power systems. Dr. Kottley has published more than 40 articles in journals and IEEE magazines and more than 30 conference papers. He is holder of 14 US patents.

Dr. Kottley is a Fellow of IEEE. He was recipient of one of the IEEE Third Millenium Medals (2000) and was the recipient of the 2002 Nikola Tesla Award.

Dr. Kottley serves as Editor in Chief of the IEEE Transactions on Energy Conversion. He is a member of CIGRE and was for a time a National Expert for Study Committee 11. He is a member of the editorial board of Electric Machines and Power Systems. He served as Conference Chairman of the International Conference on Electric Machines, 1990, and was Program Chair of the International Electric Machines and Drives Conference, 2001; both conferences were held in Cambridge, MA. Dr. Kottley is a Registered Professional Engineer in Massachusetts.

Steven B. Liebs received his Bachelor of Science and Doctoral degrees from the Massachusetts Institute of Technology in 1987, and 1993, respectively. He currently serves as Professor in the Department of Electrical Engineering and Computer Science and the Laboratory for Electromagnetic and Electronic Systems. Dr. Liebs is concerned with the design, analysis, development, and maintenance processes for all kinds of machinery with electrical actuators, sensors, or power electronic drives. He is particularly interested in the study of mechatronics: devices that are high performance systems designed to exhibit an extraordinary power density, volume, range or quality of motion, or combination of these and other qualities. A major thrust in his current research is the development of power electronic drives and supplies for servomechanical and industrial applications, including medical drug delivery devices, battery chargers, motion controllers and fluorescent lamp ballasts.

He is the author or co-author of over 50 publications and 9 patents in the fields of electromechanics and power electronics. He is a senior member of the IEEE. He has recently served as guest editor for a special issue of the IEEE Transactions on Digital Control in Power Electronics. He also serves as an officer in the IEEE Power Electronics Society. He has received a number of teaching awards at MIT, including the Bose and Spira teaching prizes.

LCR Electronics specializes in design, development and manufacturing of custom and standard EMI filters (RFI filters, EMC filters), EMC solutions, Motor controls, Electronic controls, Subsystem enclosures and back planes. We also supply Wire harness & cable assemblies, suppression Coils, chokes & inductors and a full range of capacitors including approved X&Y capacitors, DC capacitors (for electronics) and Motor run capacitors.

LCR’s products are used by numerous customers from various industries including the Appliance, Military, Aerospace, Commercial, Industrial, Telecommunication and Medical markets.

Motor Controls

LCR designs and Manufactures custom (small and large volume) electronic controllers for various motors like Universal, DC Brush, Brushless, Shaded Pole, Wound Field, Switched Reluctance and more. LCR’s controllers are EMC friendly designed, with EMI/EMC Filtering on-board where necessary.

Electronic Controls

In addition to Motor controls, we also design, develop and manufacture Electronic controls for various applications. We design controls for customers serving both domestic and international market.

Subsystem Enclosures and Backplane

LCR Electronics, Inc has bought all the equipment and intellectual property of Malco Technologies, LLC. Please contact LCR Electronics, Inc for all your future subsystem enclosure and backplane needs.

 

Wire Harness & Cable Assemblies

LCR engineers and provides wire harnesses and cable assemblies for their appliance and commercial customers.

EMI/EMC/RFI Suppression Components

LCR carries a large range and inventory of X&Y Suppression capacitors, electronic capacitors, motor run capacitors, coils, chokes and inductors.

EMC Testing

LCR has two full equipped EMC/EMI test labs where products are tested and EMC solutions are developed to economically bring equipment into compliance.

Engineering Services & Seminars

LCR provides Consulting Services, Seminars, Design Application Assistance and Comprehensive Testing for EMI, EMC, RFI and electronic motor controls

AutomationDirect now offers a wider variety of AC variable speed motors (both inverter-duty and vector-duty motors) from Marathon Electric Manufacturing Corporation®. These vector-duty and inverter-duty industrial motor models, unless otherwise stated, are rated for continuous operation in a 40 C ambient and for altitudes up to 3,300 feet (1,000 meters) above sea level.

The Marathon Electric motor lines have been carefully selected to be performance-matched with the DURAPULSE and GS series AC drives. The offering includes models ranging from ¼ hp to 100 hp, that feature dual 230/460 VAC and 575 VAC voltages and a base speed of 1200 or 1800 RPM.

AutomationDirect is proud to partner with Marathon Electric to provide our customers with premium quality AC motor models for your blower motor, induction motor, pump motor or other industrial motor applications at great prices. Marathon Electric has over 15 years experience in the design, manufacturing and application of AC variable speed motors and well over 15,000 hours of laboratory testing in state-of-the-art facilities. Marathon Electric's expertise in the application of AC drives with all induction motor products is unsurpassed. Plus, at AutomationDi rect, you can purchase a Marathon motor at an incredibly affordable price.

An electric motor converts electrical energy into mechanical energy. The reverse task, that of converting mechanical energy into electrical energy, is accomplished by a generator or dynamo. Traction motors used on locomotives often perform both tasks if the locomotive is equipped with dynamic brakes. Electric motors are found in household appliances such as fans, fridges, washing machines, pool pumps and fan-forced ovens.

Most electric motors work by electromagnetism, but motors based on other electromechanical phenomena, such as electrostatic forces and the piezoelectric effect, also exist. The fundamental principle upon which electromagnetic motors are based is that there is a mechanical force on any current-carrying wire contained within a magnetic field. The force is described by the Lorentz force law and is perpendicular to both the wire and the magnetic field. Most magnetic motors are rotary, but linear motors also exist. In a rotary motor, the rotating part (usually on the inside) is called the rotor, and the stationary part is called the stator. The rotor rotates because the wires and magnetic field are arranged so that a torque is developed about the rotor's axis. The motor contains electromagnets that are wound on a frame. Though this frame is often called the armature, that term is often erroneously applied. Correctly, the armature is that part of the motor across which the input voltage is supplied. Depending upon the design of the machine, either the rotor or the stator can serve as the armature.

Contents [hide]

1 History and Development

2 DC motors

3 Speed control

4 Universal motors

5 AC Motors

5.1 Components and types

5.2 Three-phase AC induction motors

5.3 Three-phase AC synchronous motors

5.4 Two-phase AC servo motors

5.5 Single-phase AC induction motors

5.6 Single-phase AC synchronous motors

6 Torque motors

7 Stepper motors

8 Brushless DC motors

9 Coreless DC motors

10 Linear motors

11 Doubly-fed electric motor

12 Singly-fed electric motor

13 Nanotube nanomotor

14 DC motor starters

14.1 Three-point starter

14.2 Four-point starter

15 Motor standards

16 See also

17 References and further reading

18 External articles

 History and Development

The principle of conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821 and consisted of a free-hanging wire dipping into a pool of mercury. A permanent magnet was placed in the middle of the pool of mercury. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a circular magnetic field around the wire. This motor is often demonstrated in school physics classes, but brine (salt water) is sometimes used in place of the toxic mercury. This is the simplest form of a class of electric motors called homopolar motors. A later refinement is the Barlow's Wheel. These were demonstration devices, unsuited to practical applications due to limited power.

The first commutator-type direct-current electric motor capable of a practical application was invented by the British scientist William Sturgeon. He was self-educated in the natural sciences and the science of electricity, and he spent much time experimenting with electricity and lecturing on the topic. In 1825, he delivered a lecture to his class at the Royal Military College in which he demonstrated a 7-ounce electromagnet capable of carrying 9 pounds (4 kilograms) of iron when a current from a single cell was sent through the electromagnet coils. In 1832, Sturgeon invented an electric motor which had a commutator, the critical part of a modern DC motor. His other achievements include the improvement of the electrochemical battery, contributions to the theory of thermo electricity, and the discovery that the atmosphere in serene weather is positively charged with respect to the earth.

A commutator-type direct-current electric motor built with the intention of commercial use was invented by the American Thomas Davenport and patented in 1837. Although several motors were built and operated equipment such as a printing press, due to the high cost of primary battery power, the motors were unsuccessful commercially and Davenport went bankrupt.

Although several inventors followed Sturgeon in the development of DC motors, in the days before electric power distribution these motors had to depend on expensive primary battery power. This meant that these motors had no practical commercial market.

The modern DC motor was invented by accident in 1873, when Zénobe Gramme connected a spinning dynamo to a second similar unit, driving it as a motor. The Gramme machine was the first industrially useful electric motor; earlier inventions were used as toys or laboratory curiosities.

DC motors

Electric motors of various sizes.DC motor rotation

A simple DC electric motor. When the coil is powered, a magnetic field is generated around the armature. The left side of the armature is pushed away from the left magnet and drawn toward the right, causing rotation.

The armature continues to rotate.

When the armature becomes horizontally aligned, the commutator reverses the direction of current through the coil, reversing the magnetic field. The process then repeats.

If the shaft of a DC motor is turned by an external force, the motor will act like a generator and produce an Electromotive force (EMF). During normal operation, the spinning of the motor produces a voltage, known as the counter-EMF (CEMF) or back EMF, because it opposes the applied voltage on the motor. This is the same EMF that is produced when the motor is used as a generator (for example when an electrical load (resistance) is placed across the terminals of the motor and the motor shaft is driven with an external torque). Therefore, the voltage drop across a motor consists of the voltage drop, due to this CEMF, and the parasitic voltage drop resulting from the internal resistance of the armature's windings. The current through a motor is given by the following equation:

I = (Vapplied − Vcemf) / Rarmature

The mechanical power produced by the motor is given by:

P = I * (Vapplied − Vcemf)

Mechanism of the DC motors:

When current passes through the coil wound around a soft iron core the side of the positive pole is acted upon by an upwards force, while the other side is acted upon by a downward force. According to Fleming's left hand rule, the forces cause a turning effect on the coil making it rotate; to make the motor rotate in a constant direction "direct current" commutators make the current reverse in direction every half a cycle thus causing the motor to rotate in the same direction.The problem facing the motor is when the plane of the coil is parallel to the magnetic field;i.e. the turning effect is ZERO-when coil is at 90 degree from its original position-yet, the coil continues to rotate by inertia.

Since the CEMF is proportional to motor speed, when an electric motor is first started or is completely stalled, there is zero CEMF. Therefore the current through the armature is much higher. This high current will produce a strong magnetic field which will start the motor spinning. As the motor spins, the CEMF increases until it is equal to the applied voltage, minus the parasitic voltage drop. At this point, there will be a smaller current flowing through the motor. Basically, the following three equations can be used to find the speed, current, and back EMF of a motor under a load:

Load = Vcemf * I

Vapplied = I * Rarmature + Vcemf

Vcemf = speed * Fluxarmature

Speed control

Generally, the rotational speed of a DC motor is proportional to the voltage applied to it, and the torque is proportional to the current. Speed control can be achieved by variable battery tappings, variable supply voltage, resistors or electronic controls. The direction of a wound field DC motor can be changed by reversing either the field or armature connections but not both. This is commonly done with a special set of contactors (direction contactors).

The effective voltage can be varied by inserting a series resistor or by an electronically controlled switching device made of thyristors, transistors, or, formerly, mercury arc rectifiers. In a circuit known as a chopper, the average voltage applied to the motor is varied by switching the supply voltage very rapidly. As the "on" to "off" ratio is varied to alter the average applied voltage, the speed of the motor varies. The percentage "on" time multiplied by the supply voltage gives the average voltage applied to the motor. Therefore, with a 100 V supply and a 25% "on" time, the average voltage at the motor will be 25 V. During the "off" time, the armature's inductance causes the current to continue flowing through a diode called a "flywheel diode", in parallel with the motor. At this point in the cycle, the supply current will be zero, and therefore the average motor current will always be higher than the supply current unless the percentage "on" time is 100%. At 100% "on" time, the supply and motor current are equal. The rapid switching wastes less energy than series resistors. This method is also called pulse width modulation, or PWM, and is often controlled by a microprocessor. An output filter is sometimes installed to smooth the average voltage applied to the motor and reduce motor noise.

Since the series-wound DC motor develops its highest torque at low speed, it is often used in traction applications such as electric locomotives, and trams. Another application is starter motors for petrol and small diesel engines. Series motors must never be used in applications where the drive can fail (such as belt drives). As the motor accelerates, the armature (and hence field) current reduces. The reduction in field causes the motor to speed up (see 'weak field' in the last section) until it destroys itself. This can also be a problem with railway motors in the event of a loss of adhesion since, unless quickly brought under control, the motors can reach speeds far higher than they would do under normal circumstances. This can not only cause problems for the motors themselves and the gears, but due to the differential speed between the rails and the wheels it can also cause serious damage to the rails and wheel treads as they heat and cool rapidly. Field weakening is used in some electronic controls to increase the top speed of an electric vehicle. The simplest form uses a contactor and field weakening resistor, the electronic control monitors the motor current and switches the field weakening resistor into circuit when the motor current reduces below a preset value (this will be when the motor is at its full design speed). Once the resistor is in circuit, the motor will increase speed above its normal speed at its rated voltage. When motor current increases, the control will disconnect the resistor and low speed torque is made available.

One interesting method of speed control of a DC motor is the Ward-Leonard control. It is a method of controlling a DC motor (usually a shunt or compound wound) and was developed as a method of providing a speed-controlled motor from an AC supply, though it is not without its advantages in DC schemes. The AC supply is used to drive an AC motor, usually an induction motor that drives a DC generator or dynamo. The DC output from the armature is directly connected to the armature of the DC motor (sometimes but not always of identical construction). The shunt field windings of both DC machines are independently excited through variable resistors. Extremely good speed control from standstill to full speed, and consistent torque, can be obtained by varying the generator and/or motor field current. This method of control was the de facto method from its development until it was superseded by solid state thyristor systems. It found service in almost any environment where good speed control was required, from passenger lifts through to large mine pit head winding gear and even industrial process machinery and electric cranes. Its principal disadvantage was that three machines were required to implement a scheme (five in very large installations, as the DC machines were often duplicated and controlled by a tandem variable resistor). In many applications, the motor-generator set was often left permanently running, to avoid the delays that would otherwise be caused by starting it up as required. Although electronic (thyristor) controllers have replaced most small to medium Ward Leonard systems, some very large ones (thousands of horsepower) remain in service. The field currents are much lower than the armature currents, allowing a moderate sized thryistor unit to control a much larger motor than it could control directly. For example, in one installation, a 300 amp thyristor unit controls the field of the generator. The generator output current is in excess of 15,000 amps, which would be prohibitively expensive (and inefficient) to control directly with thyristors.

Universal motors

A variant of the wound field DC motor is the universal motor. The name derives from the fact that it may use AC or DC supply current, although in practice they are nearly always used with AC supplies. The principle is that in a wound field DC motor the current in both the field and the armature (and hence the resultant magnetic fields) will alternate (reverse polarity) at the same time, and hence the mechanical force generated is always in the same direction. In practice, the motor must be specially designed to cope with the AC current (impedance must be taken into account, as must the pulsating force), and the resultant motor is generally less efficient than an equivalent pure DC motor. Operating at normal power line frequencies, the maximum output of universal motors is limited and motors exceeding one kilowatt are rare. But universal motors also form the basis of the traditional railway traction motor. In this application, to keep their electrical efficiency high, they were operated from very low frequency AC supplies, with 25 Hz and 16 2/3 hertz operation being common. Because they are universal motors, locomotives using this design were also commonly capable of operating from a third rail powered by DC.

The advantage of the universal motor is that AC supplies may be used on motors which have the typical characteristics of DC motors, specifically high starting torque and very compact design if high running speeds are used. The negative aspect is the maintenance and short life problems caused by the commutator. As a result such motors are usually used in AC devices such as food mixers and power tools which are used only intermittently. Continuous speed control of a universal motor running on AC is very easily accomplished using a thyristor circuit, while stepped speed control can be accomplished using multiple taps on the field coil. Household blenders that advertise many speeds frequently combine a field coil with several taps and a diode that can be inserted in series with the motor (causing the motor to run on half-wave rectified AC).

Universal motors can rotate at relatively high revolution per minute (rpm). This makes them useful for appliances such as blenders, vacuum cleaners, and hair dryers where high-speed operation is desired. Many vacuum cleaner and weed trimmer motors exceed 10,000 rpm, Dremel and other similar miniature grinders will often exceed 30,000 rpm. Motor damage may occur due to overspeed (rpm in excess of design specifications) if the unit is operated with no significant load. On larger motors, sudden loss of load is to be avoided, and the possibility of such an occurrence is incorporated into the motor's protection and control schemes.

With the very low cost of semiconductor rectifiers, some applications that would have previously used a universal motor now use a pure DC motor, sometimes with a permanent magnet field.

AddThis Social Bookmark Button

AC Motors

In 1882, Nikola Tesla identified the rotating magnetic field principle, and pioneered the use of a rotary field of force to operate machines. He exploited the principle to design a unique two-phase induction motor in 1883. In 1885, Galileo Ferraris independently researched the concept. In 1888, Ferraris published his research in a paper to the Royal Academy of Sciences in Turin.

Introduction of Tesla's motor from 1888 onwards initiated what is sometimes referred to as the Second Industrial Revolution, making possible the efficient generation and long distance distribution of electrical energy using the alternating current transmission system, also of Tesla's invention (1888).[1] Before the invention of the rotating magnetic field, motors operated by continually passing a conductor through a stationary magnetic field (as in homopolar motors).

Tesla had suggested that the commutators from a machine could be removed and the device could operate on a rotary field of force. Professor Poeschel, his teacher, stated that would be akin to building a perpetual motion machine.[2] Tesla would later attain U.S. Patent 0416194 , Electric Motor (December 1889), which resembles the motor seen in many of Tesla's photos. This classic alternating current electro-magnetic motor was an induction motor.

Michail Osipovich Dolivo-Dobrovolsky later invented a three-phase "cage-rotor" in 1890. This type of motor is now used for the vast majority of commercial applications.

Components and types

A typical AC motor consists of two parts:

An outside stationary stator having coils supplied with AC current to produce a rotating magnetic field, and;

An inside rotor attached to the output shaft that is given a torque by the rotating field.

There are two fundamental types of AC motor, depending on the type of rotor used:

The synchronous motor, which rotates exactly at the supply frequency or a submultiple of the supply frequency, and;

The induction motor, which turns slightly slower, and typically (though not necessarily always) takes the form of the squirrel cage motor.

Three-phase AC induction motors

Three phase AC induction motors rated 1 Hp (746 W) and 25 W with small motors from CD player, toy and CD/DVD drive reader head traverse

Disassembled 250W motor from a washing machine. The 12 stator windings are in the housing on the left. Next to it is the "squirrel cage" rotor on its shaft.Where a polyphase electrical supply is available, the three-phase (or polyphase) AC induction motor is commonly used, especially for higher-powered motors. The phase differences between the three phases of the polyphase electrical supply create a rotating electromagnetic field in the motor.

Through electromagnetic induction, the rotating magnetic field induces a current in the conductors in the rotor, which in turn sets up a counterbalancing magnetic field that causes the rotor to turn in the direction the field is rotating. The rotor must always rotate slower than the rotating magnetic field produced by the polyphase electrical supply; otherwise, no counterbalancing field will be produced in the rotor.

Induction motors are the workhorses of industry and motors up to about 500 kW (670 horsepower) in output are produced in highly standardized frame sizes, making them nearly completely interchangeable between manufacturers (although European and North American standard dimensions are different). Very large induction motors are capable of tens of thousands of kW in output, for pipeline compressors, wind-tunnel drives and overland conveyor systems.

There are two types of rotors used in induction motors.

Squirrel Cage rotors: Most common AC motors use the squirrel cage rotor, which will be found in virtually all domestic and light industrial alternating current motors. The squirrel cage takes its name from its shape - a ring at either end of the rotor, with bars connecting the rings running the length of the rotor. It is typically cast aluminum or copper poured between the iron laminates of the rotor, and usually only the end rings will be visible. The vast majority of the rotor currents will flow through the bars rather than the higher-resistance and usually varnished laminates. Very low voltages at very high currents are typical in the bars and end rings; high efficiency motors will often use cast copper in order to reduce the resistance in the rotor.

In operation, the squirrel cage motor may be viewed as a transformer with a rotating secondary - when the rotor is not rotating in sync with the magnetic field, large rotor currents are induced; the large rotor currents magnetize the rotor and interact with the stator's magnetic fields to bring the rotor into synchronization with the stator's field. An unloaded squirrel cage motor at synchronous speed will consume electrical power only to maintain rotor speed against friction and resistance losses; as the mechanical load increases, so will the electrical load - the electrical load is inherently related to the mechanical load. This is similar to a transformer, where the primary's electrical load is related to the secondary's electrical load.

This is why, as an example, a squirrel cage blower motor may cause the lights in a home to dim as it starts, but doesn't dim the lights when its fanbelt (and therefore mechanical load) is removed. Furthermore, a stalled squirrel cage motor (overloaded or with a jammed shaft) will consume current limited only by circuit resistance as it attempts to start. Unless something else limits the current (or cuts it off completely) overheating and destruction of the winding insulation is the likely outcome.

Virtually every washing machine, dishwasher, standalone fan, record player, etc. uses some variant of a squirrel cage motor.

Wound Rotor: An alternate design, called the wound rotor, is used when variable speed is required. In this case, the rotor has the same number of poles as the stator and the windings are made of wire, connected to slip rings on the shaft. Carbon brushes connect the slip rings to an external controller such as a variable resistor that allows changing the motor's slip rate. In certain high-power variable speed wound-rotor drives, the slip-frequency energy is captured, rectified and returned to the power supply through an inverter.

Compared to squirrel cage rotors, wound rotor motors are expensive and require maintenance of the slip rings and brushes, but they were the standard form for variable speed control before the advent of compact power electronic devices. Transistorized inverters with variable-frequency drive can now be used for speed control, and wound rotor motors are becoming less common. (Transistorized inverter drives also allow the more-efficient three-phase motors to be used when only single-phase mains current is available, but this is never used in household appliances, because it can cause electrical interference and because of high power requirements.)

Several methods of starting a polyphase motor are used. Where the large inrush current and high starting torque can be permitted, the motor can be started across the line, by applying full line voltage to the terminals (Direct-on-line, DOL). Where it is necessary to limit the starting inrush current (where the motor is large compared with the short-circuit capacity of the supply), reduced voltage starting using either series inductors, an autotransformer, thyristors, or other devices are used. A technique sometimes used is star-delta starting, where the motor coils are initially connected in wye for acceleration of the load, then switched to delta when the load is up to speed. This technique is more common in Europe than in North America. Transistorized drives can directly vary the applied voltage as required by the starting characteristics of the motor and load.

This type of motor is becoming more common in traction applications such as locomotives, where it is known as the asynchronous traction motor.

The speed of the AC motor is determined primarily by the frequency of the AC supply and the number of poles in the stator winding, according to the relation:

Ns = 120F / p

where

Ns = Synchronous speed, in revolutions per minute

F = AC power frequency

p = Number of poles per phase winding

Actual RPM for an induction motor will be less than this calculated synchronous speed by an amount known as slip, that increases with the torque produced. With no load, the speed will be very close to synchronous. When loaded, standard motors have between 2-3% slip, special motors may have up to 7% slip, and a class of motors known as torque motors are rated to operate at 100% slip (0 RPM/full stall).

The slip of the AC motor is calculated by:

S = (Ns − Nr) / Ns

percentageslip = (Ns − Nr) / Ns * 100

where

Nr = Rotational speed, in revolutions per minute.

S = Normalised Slip, 0 to 1.

As an example, a typical four-pole motor running on 60 Hz might have a nameplate rating of 1725 RPM at full load, while its calculated speed is 1800 RPM.

The speed in this type of motor has traditionally been altered by having additional sets of coils or poles in the motor that can be switched on and off to change the speed of magnetic field rotation. However, developments in power electronics mean that the frequency of the power supply can also now be varied to provide a smoother control of the motor speed.

Three-phase AC synchronous motors

If connections to the rotor coils of a three-phase motor are taken out on slip-rings and fed a separate field current to create a continuous magnetic field (or if the rotor consists of a permanent magnet), the result is called a synchronous motor because the rotor will rotate in synchronism with the rotating magnetic field produced by the polyphase electrical supply.

The synchronous motor can also be used as an alternator.

Nowadays, synchronous motors are frequently driven by transistorized variable-frequency drives. This greatly eases the problem of starting the massive rotor of a large synchronous motor. They may also be started as induction motors using a squirrel-cage winding that shares the common rotor: once the motor reaches synchronous speed, no current is induced in the squirrel-cage winding so it has little effect on the synchronous operation of the motor, aside from stabilizing the motor speed on load changes.

Synchronous motors are occasionally used as traction motors; the TGV may be the best-known example of such use.

One apparently unusual use for this type of motor was its use in a power factor correction scheme. This exploited a feature of the machine where it consumed power at a leading power factor when its rotor was over excited. It thus appeared to the supply to be a capacitor, and could thus be used to correct the lagging power factor that was usually presented to the electric supply. The excitation was adjusted until a near unity power factor was obtained (often automatically). Machines used for this purpose were easily identified as they had no shaft extensions. They were refered to as synchronous capacitors.

Some of the largest AC motors are pumped-storage hydroelectricity generators that are operated as synchronous motors to pump water to a reservoir at a higher elevation for later use to generate electricity using the same machinery. Six 350-megawatt generators are installed in the Bath County Pumped Storage Station in Warm Springs, VA USA. When pumping, each unit can produce 563,400 horsepower (420,127 kilowatts).[3]

Two-phase AC servo motors

A typical two-phase AC servo motor has a squirrel-cage rotor and a field consisting of two windings: 1) a constant-voltage (AC) main winding, and 2) a control-voltage (AC) winding in quadrature with the main winding so as to produce a rotating magnetic field. The electrical resistance of the rotor is made high intentionally so that the speed-torque curve is fairly linear. Two-phase servo motors are inherently high-speed, low-torque devices, heavily geared down to drive the load.

Single-phase AC induction motors

Three-phase motors inherently produce a rotating magnetic field. However, when only single-phase power is available, the rotating magnetic field must be produced using other means. Several methods are commonly used.

A common single-phase motor is the shaded-pole motor, which is used in devices requiring low torque, such as electric fans or other small household appliances. In this motor, small single-turn copper "shading coils" create the moving magnetic field. Part of each pole is encircled by a copper coil or strap; the induced current in the strap opposes the change of flux through the coil (Lenz's Law), so that the maximum field intensity moves across the pole face on each cycle, thus producing the required rotating magnetic field.

Another common single-phase AC motor is the split-phase induction motor, commonly used in major appliances such as washing machines and clothes dryers. Compared to the shaded pole motor, these motors can generally provide much greater starting torque by using a special startup winding in conjunction with a centrifugal switch.

In the split-phase motor, the startup winding is designed with a higher resistance than the running winding. This creates an LR circuit which slightly shifts the phase of the current in the startup winding. When the motor is starting, the startup winding is connected to the power source via a set of spring-loaded contacts pressed upon by the not-yet-rotating centrifugal switch. The starting winding is wound with fewer turns of smaller wire than the main winding, so it has a lower inductance (L) and higher resistance (R). The lower L/R ratio creates a small phase shift, not more than about 30 degrees, between the flux due to the main winding and the flux of the starting winding. The starting direction of rotation may be reversed simply by exchanging the connections of the startup winding relative to the running winding.

The phase of the magnetic field in this startup winding is shifted from the phase of the mains power, allowing the creation of a moving magnetic field which starts the motor. Once the motor reaches near design operating speed, the centrifugal switch activates, opening the contacts and disconnecting the startup winding from the power source. The motor then operates solely on the running winding. The starting winding must be disconnected since it would increase the losses in the motor.

In a capacitor start motor, a starting capacitor is inserted in series with the startup winding, creating an LC circuit which is capable of a much greater phase shift (and so, a much greater starting torque). The capacitor naturally adds expense to such motors.

Another variation is the Permanent Split-Capacitor (PSC) motor (also known as a capacitor start and run motor). This motor operates similarly to the capacitor-start motor described above, but there is no centrifugal starting switch and the second winding is permanently connected to the power source. PSC motors are frequently used in air handlers, fans, and blowers and other cases where a variable speed is desired. By changing taps on the running winding but keeping the load constant, the motor can be made to run at different speeds. Also provided all 6 winding connections are available separately, a 3 phase motor can be converted to a capacitor start and run motor by commoning two of the windings and connecting the third via a capacitor to act as a start winding.

Repulsion motors are wound-rotor single-phase AC motors that are similar to universal motors. In a repulsion motor, the armature brushes are shorted together rather than connected in series with the field. Several types of repulsion motors have been manufactured, but the repulsion-start induction-run (RS-IR) motor has been used most frequently. The RS-IR motor has a centrifugal switch that shorts all segments of the commutator so that the motor operates as an induction motor once it has been accelerated to full speed. RS-IR motors have been used to provide high starting torque per ampere under conditions of cold operating temperatures and poor source voltage regulation. Few repulsion motors of any type are sold as of 2006.

Single-phase AC synchronous motors

Small single-phase AC motors can also be designed with magnetized rotors (or several variations on that idea). The rotors in these motors do not require any induced current so they do not slip backward against the mains frequency. Instead, they rotate synchronously with the mains frequency. Because of their highly accurate speed, such motors are usually used to power mechanical clocks, audio turntables, and tape drives; formerly they were also much used in accurate timing instruments such as strip-chart recorders or telescope drive mechanisms. The shaded-pole synchronous motor is one version.

Because inertia makes it difficult to instantly accelerate the rotor from stopped to synchronous speed, these motors normally require some sort of special feature to get started. Various designs use a small induction motor (which may share the same field coils and rotor as the synchronous motor) or a very light rotor with a one-way mechanism (to ensure that the rotor starts in the "forward" direction).

Torque motors

A torque motor is a specialized form of induction motor which is capable of operating indefinitely at stall (with the rotor blocked from turning) without damage. In this mode, the motor will apply a steady torque to the load (hence the name). A common application of a torque motor would be the supply- and take-up reel motors in a tape drive. In this application, driven from a low voltage, the characteristics of these motors allow a relatively-constant light tension to be applied to the tape whether or not the capstan is feeding tape past the tape heads. Driven from a higher voltage, (and so delivering a higher torque), the torque motors can also achieve fast-forward and rewind operation without requiring any additional mechanics such as gears or clutches. In the computer world, torque motors are used with force feedback steering wheels.

Stepper motors

Main article: Stepper motor

Closely related in design to three-phase AC synchronous motors are stepper motors, where an internal rotor containing permanent magnets or a large iron core with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the motor may not rotate continuously; instead, it "steps" from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards.

Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions; more sophisticated drivers can proportionally control the power to the field windings, allowing the rotors to position "between" the "cog" points and thereby rotate extremely smoothly. Computer controlled stepper motors are one of the most versatile forms of positioning systems, particularly when part of a digital servo-controlled system.

Stepper motors can be rotated to a specific angle with ease, and hence stepper motors are used in pre-gigabyte era computer disk drives, where the precision they offered was adequate for the correct positioning of the read/write head of a hard disk drive. As drive density increased, the precision limitations of stepper motors made them obsolete for hard drives, thus newer hard disk drives use read/write head control systems based on voice coils.

Stepper motors were upscaled to be used in electric vehicles under the term SRM (switched reluctance machine).

source [1]

Brushless DC motors

Main article: Brushless DC electric motor

Many of the limitations of the classic commutator DC motor are due to the need for brushes to press against the commutator. This creates friction. At higher speeds, brushes have increasing difficulty in maintaining contact. Brushes may bounce off the irregularities in the commutator surface, creating sparks. This limits the maximum speed of the machine. The current density per unit area of the brushes limits the output of the motor. The imperfect electric contact also causes electrical noise. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance. The commutator assembly on a large machine is a costly element, requiring precision assembly of many parts.

These problems are eliminated in the brushless motor. In this motor, the mechanical "rotating switch" or commutator/brushgear assembly is replaced by an external electronic switch synchronised to the rotor's position. Brushless motors are typically 85-90% efficient, whereas DC motors with brushgear are typically 75-80% efficient.

Midway between ordinary DC motors and stepper motors lies the realm of the brushless DC motor. Built in a fashion very similar to stepper motors, these often use a permanent magnet external rotor, three phases of driving coils, one or more Hall effect devices to sense the position of the rotor, and the associated drive electronics. The coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall effect sensors. In effect, they act as three-phase synchronous motors containing their own variable-frequency drive electronics. A specialized class of brushless DC motor controllers utilize EMF feedback through the main phase connections instead of Hall effect sensors to determine position and velocity. These motors are used extensively in electric radio-controlled vehicles, and referred to by modelists as outrunner motors (since the magnets are on the outside).

Brushless DC motors are commonly used where precise speed control is necessary, computer disk drives or in video cassette recorders the spindles within CD, CD-ROM (etc.) drives, and mechanisms within office products such as fans, laser printers and photocopiers. They have several advantages over conventional motors:

Compared to AC fans using shaded-pole motors, they are very efficient, running much cooler than the equivalent AC motors. This cool operation leads to much-improved life of the fan's bearings.

Without a commutator to wear out, the life of a DC brushless motor can be significantly longer compared to a DC motor using brushes and a commutator. Commutation also tends to cause a great deal of electrical and RF noise; without a commutator or brushes, a brushless motor may be used in electrically sensitive devices like audio equipment or computers.

The same Hall effect devices that provide the commutation can also provide a convenient tachometer signal for closed-loop control (servo-controlled) applications. In fans, the tachometer signal can be used to derive a "fan OK" signal.

The motor can be easily synchronized to an internal or external clock, leading to precise speed control.

Brushless motors have no chance of sparking, unlike brushed motors, making them better suited to environments with volatile chemicals and fuels.

Brushless motors are usually used in small equipment such as computers generaly used to get rid of unwanted heat.

They are also very quiet motors which is an advantage if being used in equipment that is affected by vibrations.

Modern DC brushless motors range in power from a fraction of a watt to many kilowatts. Larger brushless motors up to about 100 kW rating are used in electric vehicles. They also find significant use in high-performance electric model aircraft.

Coreless DC motors

Nothing in the design of any of the motors described above requires that the iron (steel) portions of the rotor actually rotate; torque is exerted only on the windings of the electromagnets. Taking advantage of this fact is the coreless DC motor, a specialized form of a brush DC motor. Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. The rotor can take the form of a winding-filled cylinder inside the stator magnets, a basket surrounding the stator magnets, or a flat pancake (possibly formed on a printed wiring board) running between upper and lower stator magnets. The windings are typically stabilized by being impregnated with epoxy resins.

Because the rotor is much lighter in weight (mass) than a conventional rotor formed from copper windings on steel laminations, the rotor can accelerate much more rapidly, often achieving a mechanical time constant under 1 ms. This is especially true if the windings use aluminum rather than the heavier copper. But because there is no metal mass in the rotor to act as a heat sink, even small coreless motors must often be cooled by forced air.

These motors were commonly used to drive the capstan(s) of magnetic tape drives and are still widely used in high-performance servo-controlled systems.

Linear motors

A linear motor is essentially an electric motor that has been "unrolled" so that, instead of producing a torque (rotation), it produces a linear force along its length by setting up a traveling electromagnetic field.

Linear motors are most commonly induction motors or stepper motors. You can find a linear motor in a maglev (Transrapid) train, where the train "flies" over the ground.

Doubly-fed electric motor

Doubly-fed electric motors or Doubly-Fed Electric Machines have two multiphase windings, with at least one of the winding sets electronically controlled for synchronous operation from sub-synchronous to super synchronous speeds. As a result, doubly-fed electric motors are synchronous machines with an effective constant torque speed range that is twice synchronous speed for a given frequency of excitation.

This is twice the constant torque speed range as Singly-Fed Electric Machines, which have only one active winding set. In theory, this attribute has attractive cost, size, and efficiency ramifications compared to Singly-Fed Electric Machines but Doubly-fed motors are difficult to realize in practice.

The Wound-Rotor Doubly-Fed Electric Machines, the Brushless Wound-Rotor Doubly-Fed Electric Machine, and the so-called Brushless Doubly-Fed Electric Machines are the only examples of synchronous doubly-fed electric machines.

Singly-fed electric motor

Singly-fed electric motors or Singly-Fed Electric Machines incorporate a single multiphase winding set that actively participate in the energy conversion process (i.e., singly-fed). Singly-fed electric machines operate under either Induction (i.e., Asynchronous) or Synchronous principles. The active winding set can be electronically controlled for optimum performance. Induction machines exhibit startup torque and can operate as standalone machines but Synchronous machines must have auxiliary means for startup and practical operation, such as an electronic controller. Singly-fed electric machines have an effective constant torque speed range up to synchronous speed (i.e., 3600 rpm @ 60 Hz and 2 Poles) for a given excitation frequency.

The Induction (Asynchronous) motors (i.e., squirrel cage rotor or wound rotor), Synchronous motors (i.e., field-excited, Permanent Magnet or brushless DC motors, Reluctance motors, etc.), which are discussed on this page, are examples of Singly-fed motors. By far, Singly-fed motors are the predominantly installed type of motors.

Nanotube nanomotor

Main article: Nanomotor

Nanomotor constructed at UC Berkeley. The motor is about 500nm across: 300 times smaller than the diameter of a human hairResearchers at University of California, Berkeley, recently developed rotational bearings based upon multiwall carbon nanotubes. By attaching a gold plate (with dimensions of order 100nm) to the outer shell of a suspended multiwall carbon nanotube (like nested carbon cylinders), they are able to electrostatically rotate the outer shell relative to the inner core. These bearings are very robust; devices have been oscillated thousands of times with no indication of wear. These nanoelectromechanical systems (NEMS) are the next step in miniaturization that may find their way into commercial aspects in the future.

Electrostatic motor

DC motor starters

The counter-emf aids the armature resistance to limit the current through the armature. When power is first applied to a motor, the armature does not rotate. At that instant the counter-emf is zero and the only factor limiting the armature current, is the armature resistance. Usually the armature resistance of a motor is less than one ohm; therefore the current through the armature would be very large when the power is applied. This current can make an excessive voltage drop affecting other equipment in the circuit and even trip overload protective devices.

Therefore the need arises for an additional resistance in series with the armature to limit the current until the motor rotation can build up the counter-emf. As the motor rotation build up, the resistance is gradually cut out.

Three-point starter

Three point starterThe incoming power is indicated as L1 and L2. The components within the broken lines form the three-point starter. As the name implies there are only three connections to the starter. The connections to the armature are indicated as A1 and A2. The ends of the field (excitement) coil are indicated as F1 and F2. In order to control the speed, A field rheostat is connected in series with the shunt field. One side of the line is connected to the arm of the starter (represented by an arrow in the diagram). The arm is spring-loaded so , it will return to the "Off" position the not held at any other position.

ON the first step of the arm, full line voltage is applied across the shunt field. Since the field rheostat is normally set to minimum resistance, the speed of the motor will not be excessive; additionally, the motor will develop a large starting torque.

The starter also connects an electromagnet in series with the shunt field. It will hold the arm in position when the arm makes contact with the magnet.

Meanwhile that voltage is applied to the shunt field, and the starting resistance limits the flow of current to the armature.

As the motor picks up speed counter-emf is built up, the arm is moved slowly to short.

Four-point starter

Four point starterThe four-point starter eliminates the drawback of the three-point starter. In addition to the same three points that were in use with the three-point starter, the other side of the line, L1, is the fourth point brought to the starter when the arm is moved from the "Off" position. The coil of the holding magnet is connected across the line. The holding magnet and starting resistors function identical as in the three-point starter.

The possibility of accidentally opening the field circuit is quite remote. The four-point starter provides the no-voltage protection to the motor. If the power fails, the motor is disconnected from the line.

Motor standards

The following are major design and manufacturing standards covering electric motors:

International Electrotechnical Commission: IEC 60034 Rotating Electrical Machines

National Electrical Manufacturers Association (USA): NEMA MG 1 Motors and Generators

See also

Electronics Portal

 Energy Portal

Motor control:

Motor controller

Motor Soft Starter

Direct on line starter

Adjustable-speed drive

Electronic speed control

Variable-frequency drive

Thyristor drive

Components:

Centrifugal switch

Commutator (electric)

Slip ring

10 100 12 12v 2 20 200 2hp 3 4 5 5hp a ac ajax an ao baldor basic basics beakman's bearing bearings bicycle bike bikes blower boat bodine brake brush brushes brushless build building buy c calculator capacitor capacitors car cars cart century city cleaner clock company control controller controls conversion cooling corp cross cycle cycles data dayton dc design diagram diagrams dimensions does drive drives efficiency electric emerson etek fan fasco first frame franklin ge gear general generator glider global golf grease high history hobby homemade horsepower how hp hp hub hybrid induction industrial johnson kit kits large lincoln linear magnetek magnetek maintenance make manufacturer manufacturers marathon mini miniature model motor mount mounts noise of ohio oil outboard parts phase plans pole power precision price project project projects pulley r r rc rc rebuild rebuilding reference reliance repair repairs replacement rewind rewinding rpm sales schematic science scooter scooters seat service shaft shop siemens simple single size sizes small smith specifications specs speed starter starters supply surplus testing theory three to torque toshiba toy trolling troubleshooting twin types universal us used variable vehicle volt vulcan warehouse weg weight westinghouse wheel winding windings window wiper wire wiring work works

Scientists and engineers:

Ottó Bláthy

Timeline of motor and engine technology

References and further reading

Citations

^ http://www.tfcbooks.com/tesla/system.htm

^ "Tesla's Early Years". PBS.

^ [|Dominion Resources, Inc.], Bath County Pumped Storage Station. Retrieved on 2007-3-30 

General references

Donald G. Fink and H. Wayne Beaty, Standard Handbook for Electrical Engineers, Eleventh Edition, McGraw-Hill, New York, 1978, ISBN 0-07-020974-X.

Edwin J. Houston and Arthur Kennelly, Recent Types of Dynamo-Electric Machinery, copyright American Technical Book Company 1897, published by P.F. Collier and Sons New York, 1902

Kuphaldt, Tony R. (2000-2006). "Chapter 13 AC MOTORS", Lessons In Electric Circuits — Volume II. 

A.O.Smith: The AC's and DC's of Electric Motors. Retrieved on 2006-04-11.

Resenblat & Frienman DC and AC machinery

Links to AC Motor Manufacturers

Further reading

Shanefield D. J., Industrial Electronics for Engineers, Chemists, and Technicians, William Andrew Publishing, Norwich, NY, 2001. A self-teaching textbook that briefly covers electric motors, transformers, speed controllers, wiring codes and grounding, transistors, digital, etc. Easy to read and understand, up to an elementary level on each subject, not a suitable reference book for technologists already working in any of those fields.

Fitzgerald/Kingsley/Kusko (Fitzgerald/Kingsley/Umans in later years), *Electric Machinery, classic text for junior and senior electrical engineering students. Originally published in 1952, 6th edition published in 2002. Authors still listed as Fitzgerald/Kingsley/Umans although Fitzgerald and Kingsley are now deceased.

Bedford, B. D.; Hoft, R. G. et al (1964). Principles of Inverter Circuits. New York: John Wiley & Sons, Inc.. 0 471 06134 4.  (Inverter circuits are used for variable-frequency motor speed control)

B. R. Pelly, "Thyristor Phase-Controlled Converters and Cycloconverters: Operation, Control, and Performance" (New York: John Wiley, 1971).

John N. Chiasson, Modeling and High Performance Control of Electric Machines, Wiley-IEEE Press, New York, 2005, ISBN 0-471-68449-X.

Some typos are related to this page: electric erectlic eectric elctric eletric elecric electrc erectrik eerctrik electlik eelctlik leectlik erectlik electrik eelctrik leectrik eelctric leectric erectric eerctric electlic eelctlic leectlic eerctlic electc electic eectic elctic eletic elecic electik eelctik leectik erectik eerctik eelctic leectic erectic eerctic eelctri electli erectli leectli eelctli eectri elctri electri eletri erectri elecri leectri electi e1ectr1c electr1c electrci electirc elecrtic eletcric elcetric lectric eelctric epectric emectric ekectric eledtric elevtric elextric elecrric elecgric elecyric electeic electtic electgic electfic electroc electruc electrkc electrid electriv electrix motor motur motol moter motos motols motoes motous motors motoars moters mours mools moors mooars notors motosr motros mootrs mtoors omtors motrs mtors otors mootr notor kotor jotor mitor mltor mptor moror mogor moyor motir motlr motpr motoe electric motor cycle reliance electric motor ohio electric motor electric motor electric vehicle motor 3 hp electric motor used electric motor electric motor company electric motor bearing electric motor hp 20 hp electric motor electric motor troubleshooting motor city electric electric motor calculator electric motor model electric motor specs miniature electric motor electric motor mounts dayton electric motor general electric motor ge electric motor electric motor rpm 5hp electric motor electric motor shaft 12 volt electric motor general electric ac motor electric motor cycles surplus electric motor electric gear motor electric motor windings electric boat motor how to build an electric motor electric car motor 12v electric motor electric trolling motor mini electric motor how to make an electric motor hobby electric motor make an electric motor electric motor oil electric outboard motor build an electric motor single phase electric motor the electric motor build electric motor electric clock motor electric motor kits toshiba electric motor electric motor weight westinghouse electric motor electric motor horsepower electric motor kit franklin electric motor high torque electric motor large electric motor electric motor pulley building an electric motor toy electric motor electric motor project electric motor science project electric motor noise magnetek universal electric motor beakman's electric motor electric motor efficiency 3 phase electric motor electric motor frame sizes parts of an electric motor electric motor grease electric bike motor electric motor schematic motot motog motof 3lectric 4lectric dlectric eectric eelctric eelectric ekectric el3ctric el4ctric elcetric elctric eldctric elec5ric elec6ric elecctric elecfric elecgric elecric elecrric elecrtic elect4ic elect5ic electdic electeic electfic electic electirc electr8c electr9c electrc electrci electri electric electric electricc electrid electrif electriic electriv electrix electrjc electrkc electroc electrric electruc electtic electtric elecyric eledtric eleectric eleftric eletcric eletric elevtric elextric ellectric elrctric elsctric elwctric eoectric epectric jotor kotor lectric leectric m0tor m9tor mitor mktor mltor mmotor mo5or mo6or mofor mogor moor mootor mootr moror mot0r mot9r motir motkr motlr moto moto4 moto5 motod motoe motof motoor motor motor motorr motot motpr motr motro mottor moyor mptor mtoor mtor notor omtor otor rlectric slectric wlectric RELIANCE aajx aax abldor absic absics aclculator acpacitor aja ajax ajax ajx ajxa alculator aldor apacitor asic asics badlor bador baekmans baering baerings baic baics baisc baiscs bake bakmans baldo baldor baldor baldr baldro balodr balor baot baring barings barke basc basci bascis bascs basi basic basic basic basics basics basis basisc bat bciycle bcycle bdine bdoine beaing beaings beairng beairngs beakamns beakans beakman beakmans beakmans beakmas beakmasn beakmnas beakmns beamans beamkans bearig bearign bearigns bearigs bearin bearing bearing bearing bearings bearings bearins bearinsg bearng bearngs bearnig bearnigs bekamans bekmans beraing beraings bering berings biccle biccyle bicyce bicycel bicycl bicycle bicycle bicylce bicyle bie biek bieks bies bik bike bike bike bikes bikes biks bikse bild bilding biuld biulding biyccle biycle bke bkes bkie bkies blador bldor bloer bloewr blowe blower blower blowr blowre blwer blwoer boa boat boat bodie bodien bodin bodine bodine bodne bodnie boidne boine bolwer bot bota bower brae braek brak brake brake brkae brke brsh brshes brshless brsuh brsuhes brsuhless bruh bruhes bruhless bruhs bruhses bruhsless brus brusehs bruses brush brush brushe brushelss brushes brushes brushess brushles brushles brushless brushless brushless brushlses brushlss brushs brushse brusless bruslhess bsaic bsaics bsic bsics bu buid buiding buidl buidling buil build build buildig buildign buildin building building buildng buildnig builidng builing buld bulding bulid buliding bursh burshes burshless bush bushes bushless buy buy by byu caacitor caapcitor caclulator caculator calclator calcluator calcualtor calcuator calculaor calculaotr calculato calculator calculator calculatr calculatro calcultaor calcultor caluclator calulator capacior capaciotr capacito capacitor capacitor capacitr capacitro capactior capactor capaictor capaitor capcaitor capcitor claculator clculator cpaacitor cpacitor eakmans earing earings ebakmans ebaring ebarings ibcycle ibke ibkes icycle ike ikes jaax jax lbower lower oat obat obdine odine rake rbake rbush rbushes rbushless rush rushes rushless ubild ubilding uby uild uilding uy acpacitors acr acrs acrt adta adyton afn afsco agnetek aintenance ake alrge amgnetek amintenance amke amnufacturer amnufacturers amrathon an anufacturer anufacturers apacitors aprts ar arathon arge ars art arts asco ata ayton c c ca caacitors caapcitors capaciors capaciotrs capacitor capacitors capacitors capacitos capacitosr capacitros capacitrs capactiors capactors capaictors capaitors capcaitors capcitors car car car car cars cars cart cart cas casr cat catr ccle ccles ccyle ccyles cd ceaner celaner centruy centry centur century century centuy centuyr cenury cenutry cetnury cetury cit city city ciy ciyt claener claner clck clcok cleaenr cleaer cleane cleaner cleaner cleanr cleanre clenaer clener cloc clock clock clok clokc cmopany cmpany cnetury cnotrol cnotroller cnotrols cnoversion cntrol cntroller cntrols cntury cnversion cock colck coling coling coloing comany comapny compan company company compay compayn compnay compny conersion conevrsion conrol conroller conrols conrtol conrtoller conrtols contol contoller contols contorl contorller contorls contrl contrller contrlo contrloler contrlos contrls contro control control control controlelr controler controler controlle controller controller controller controllr controllre controls controls contros controsl converion converison conversin conversino conversio conversion conversion conversoin converson convesion convesrion convresion convrsion cooilng cooing coolig coolign coolin cooling cooling cooling coolng coolnig cop copany copmany copr cor corp corp corss coss cotnrol cotnroller cotnrols cotrol cotroller cotrols coversion covnersion cpaacitors cpacitors cr cr cra cras crat crop cros cros cross cross cross crp crs crsos crss crt ctiy cty cyce cycel cycels cyces cycl cycle cycle cycle cycles cycles cycls cyclse cylce cylces cyle cyles d daa daat dagram dagrams daigram daigrams dat data data daton datyon dayon dayotn daytn daytno dayto dayton dayton dc dc deign deisgn deos des desgin desgn desig design design desin desing diagam diagams diagarm diagarms diagra diagram diagram diagram diagrams diagrams diagras diagrasm diagrm diagrma diagrmas diagrms diaram diarams diargam diargams diemnsions diensions digaram digarams digram digrams dimenions dimenisons dimensinos dimensins dimension dimensions dimensions dimensios dimensiosn dimensoins dimensons dimesions dimesnions dimnesions dimnsions dirve dirves dive dives dmensions dmiensions doe does does dos dose drie dries driev drievs driv drive drive drive drives drives drivs drivse drve drves drvie drvies dseign dsign dta dtaa dyaton dyton e ear ebuild ebuilding ecntury edsign eectric eek eelctric eemrson eerson eetk eference effciency effciiency efficeincy efficency efficiecny efficiecy efficienc efficiency efficiency efficiency efficieny efficienyc efficincy efficinecy effiicency effiiency eficiency eficiency efifciency eg egar egneral egnerator elcetric elctric elecric elecrtic electic electirc electrc electrci electri electric electric eletcric eletric eliance emeron emerosn emersn emersno emerso emerson emerson emeson emesron emreson emrson eneral enerator entury erbuild erbuilding erference erliance esign ete etek etek etk etke f fa faco facso fame fan fan fanklin farme farnklin fasc fasco fasco faso fasoc feficiency fficiency firs first first firt firts fisrt fist fn fna fo frae fraem fraklin fraknlin fram frame frame frankiln frankin frankli franklin franklin frankln franklni franlin franlkin frist frmae frme frnaklin frnklin frst fsaco fsco g gaer gar ge ge gea gear gear gease geenral geenrator geeral geerator geneal genearl geneartor geneator genera general general generaor generaotr generato generator generator generatr generatro generl generla genertaor genertor genral genrator genreal genreator ger gera gerase gider gilder glbal glboal glder gldier glf glide glider glider glidr glidre gliedr glier gloabl gloal globa global global globl globla glof gneeral gneerator gneral gnerator gobal gof gofl gol golbal golf golf graese grase greae greaes greas grease grease gresae grese h hase hb hbby hboby hbrid hbu hbyrid hgh hgih hig high high hih hihg hio hisory hisotry histor history history histoy histoyr histroy histry hitory hitsory hmemade hmoemade ho hobb hobby hobby hobby hoby hoby hobyb hoemade hoemmade hoio homeade homeamde homemad homemade homemade homemae homemaed homemdae homemde hommade hommeade horepower horespower horseopwer horseower horsepoer horsepoewr horsepowe horsepower horsepower horsepowr horsepowre horsepwer horsepwoer horspeower horspower hosepower hosrepower how how hp hp hpase hrosepower hrsepower hsitory hstory hu hub hub hw hwo hybid hybird hybrd hybrdi hybri hybrid hybrid hyrbid hyrid iagram iagrams icty idagram idagrams idmensions idnuction idnustrial iduction idustrial ifrst igh ihgh ihstory ikt ikts il ilncoln ilnear imensions imni imniature incoln indction indcution indstrial indsutrial inducion induciton inductin inductino inductio induction induction inductoin inducton indusrial indusrtial industial industiral industrail industral industria industrial industrial industril industrila indutcion indution indutrial indutsrial inear ini iniature inuction inudction inudstrial inustrial iol irst istory it its ity jhnson jhonson johnon johnosn johnsn johnsno johnso johnson johnson johsnon johson jonhson jonson ki kis kist kit kit kit kits kits kt kti ktis kts lage lagre lans lare lareg larg large large lceaner lcock leaner lectric leectric lgider lgobal licnoln licoln lider liear lienar linaer linar lincln linclon lincol lincoln lincoln lincon linconl linea linear linear liner linera linocln linoln lncoln lnear lnicoln lniear lobal lock lpans lrage lrge maarthon maathon mae maek magentek magetek magneek magneetk magnete magnetek magnetek magnetk magnetke magnteek magntek mainenance mainetnance mainteance mainteannce maintenace maintenacne maintenanc maintenance maintenance maintenane maintenanec maintennace maintennce maintnance maintneance maitenance maitnenance mak make make manetek manfacturer manfacturers manfuacturer manfuacturers mangetek manitenance mantenance manuacturer manuacturers manuafcturer manuafcturers manufactrer manufactrers manufactruer manufactruers manufactuer manufactuerr manufactuerrs manufactuers manufacture manufacturer manufacturer manufacturer manufacturers manufacturers manufactures manufacturesr manufacturr manufacturre manufacturres manufacturrs manufacurer manufacurers manufacutrer manufacutrers manufatcurer manufatcurers manufaturer manufaturers manufcaturer manufcaturers manufcturer manufcturers marahon marahton marathn marathno maratho marathon marathon maratohn maraton martahon marthon maufacturer maufacturers maunfacturer maunfacturers mdel mdoel meerson merson mganetek mgnetek miantenance mii miiature miin miinature min minaiture minature mini mini miniatre miniatrue miniatue miniatuer miniatur miniature miniature miniaure miniautre minitaure miniture mintenance mkae mke mnaufacturer mnaufacturers mni mniature mnii mniiature mnufacturer mnufacturers mode model model modl modle moedl moel mont monts monut monuts moor mootr moto motor motor motr motro moun mouns mounst mount mount mount mounts mounts mout moutn moutns mouts mraathon mrathon mtoor mtor munt munts muont muonts nduction ndustrial niduction nidustrial niose nise noie noies nois noise noise nose nosie o obby ocmpany ocntrol ocntroller ocntrols ocnversion ocoling ocrp odel odes oes of of oglf ohbby ohi ohio ohio ohmemade ohnson oho ohoi ohrsepower ohw oi oiho oil oil oio oise ojhnson ol ole olf oli omdel omemade ompany omtor omunt omunts onise ontrol ontroller ontrols onversion ooling ople opwer orp orsepower otboard otor otuboard ouboard oubtoard ount ounts outbaord outbard outboad outboadr outboar outboard outboard outborad outbord outoard outobard ow ower p pahse palns pans pars parst part parts parts pase patrs pats pecision percision ph phae phaes phas phase phase phsae phse pice pirce plan plans plans plas plasn ple plley plnas plns ploe pluley poe poel poer poewr poject pojects pol pole pole porject porjects powe power power powr powre prats prce prceision prcie prcision preciion preciison precisin precisino precisio precision precision precisoin precison precsiion precsion preicsion preision pric price price prie priec prject prjects prjoect prjoects proect proects proejct proejcts projcet projcets projct projcts projec projecs projecst project project project projects projects projet projetc projetcs projets prts pulely puley puley pulle pulley pulley pulley pully pullye pwer pwoer r r r rame ranklin rbeuild rbeuilding rbuild rbuilding rc rc rcoss rdive rdives rease rebild rebilding rebiuld rebiulding rebuid rebuiding rebuidl rebuidling rebuil rebuild rebuild rebuildig rebuildign rebuildin rebuilding rebuilding rebuildng rebuildnig rebuilidng rebuiling rebuld rebulding rebulid rebuliding recision reefrence reerence refeence refeernce referece referecne referenc reference reference referene referenec refernce refernece refreence refrence reiance reilance relaince relance reliace reliacne relianc reliane relianec relinace relince reubild reubilding reuild reuilding rfame rfanklin rfeerence rference rgease rice rive rives rleiance rliance roject rojects ross rpecision rpice rpoject rpojects teek tek ub uhb ulley uotboard uplley utboard ybrid yccle yccles ycle ycles hybrid ales arehouse ariable asles avriable awrehouse chematic cience cooter cooters cshematic csience csooter csooters eat eg ehicle eight epair epairs eplacement erpair erpairs erplacement ervice erwind erwinding esat esrvice esting estinghouse etsting evhicle ewg ewight ewind ewinding ewstinghouse haft heel heory hop hree hsaft hsop hteory htree hweel iemens imple inding indings indow ingle iper ire iring isemens ismple isngle isze iszes iwnding iwndings iwndow iwper iwre iwring ize izes mall mith msall msith niversal nuiversal o olt ork orks orque oshiba ot otrque otshiba oty ovlt owrk owrks oy pecifications pecs peed pm prm psecifications psecs pseed reair reairs reapir reapirs reind reinding reiwnd reiwnding relacement relpacement repacement repai repair repair repair repairs repairs repais repaisr repalcement repar repari reparis repars repiar repiars repir repirs replaceemnt replaceent replacemen replacement replacement replacemet replacemetn replacemnet replacemnt replacmeent replacment replaecment replaement replcaement replcement rewid rewiding rewidn rewidning rewin rewind rewind rewindig rewindign rewindin rewinding rewinding rewindng rewindnig rewinidng rewining rewnd rewnding rewnid rewniding rm rmp rolling roubleshooting rp rpair rpairs rpeair rpeairs rpelacement rplacement rpm rpm rtolling rtoubleshooting rweind rweinding rwind rwinding s saels saes saet saft sahft sale sales sales sall sals salse samll sarter sarters sat satrter satrters scehmatic sceince scematic scence scheamtic scheatic schemaic schemaitc schematc schematci schemati schematic schematic schemtaic schemtic schmatic schmeatic sciece sciecne scienc science science sciene scienec scince scinece scooer scooers scooetr scooetrs scoote scooter scooter scooter scooter scooters scooters scooters scootes scootesr scootr scootre scootres scootrs scoter scoter scoters scoters scotoer scotoers sea seat seat secifications secs sed seed seimens semens sepcifications sepcs seped serice serivce servce servcie servic service service servie serviec set seta sevice sevrice shaf shaft shaft shat shatf shcematic shematic shfat shft sho shop shop shp shpo sicence sie sieemns sieens siemen siemens siemens siemes siemesn siemnes siemns sience sies siez siezs sigle signle simeens simens simle simlpe simpe simpel simpl simple simple simth singe singel singl single single sinle sinlge siple sipmle sith siz size size size sizes sizes sizs sizse slaes sles smal smal small small small smih smiht smiple smit smith smith smlal smll smple smth smtih sngle snigle socoter socoters sohp sooter sooters sop spceifications spces spcifications spcs spec specfications specfiications specifcations specifciations specifiactions specifiations specificaions specificaitons specificatinos specificatins specification specifications specifications specificatios specificatiosn specificatoins specificatons specifictaions specifictions speciications speciifcations specs specs sped sped spede spee speed speed speed speicfications speifications spes spesc spply spuply srevice srplus sruplus srvice starer starers staretr staretrs starte starter starter starter starters starters startes startesr startr startre startres startrs stater staters statrer statrers strater straters strter strters su sued suplpy suplus suply suply suppl supply supply supply suppy suppyl suprlus surlpus surlus surpls surplsu surplu surplus surplus surpuls surpus sze szes szie szies t tarter tarters tehory teory tesing tesitng testig testign testin testing testing testng testnig teting tetsing thee theor theory theory theoy theoyr there theroy thery thoery thory thre thre three three three tin tiwn to to to tohiba tohsiba tolling toqrue toque torlling torqe torqeu torqu torque torque torubleshooting torue toruqe toshba toshbia toshia toshiab toshib toshiba toshiba tosiba tosihba toubleshooting toy toy tpes tpyes tree trhee trlling trloling trobleshooting trobuleshooting trolilng troling troling trollig trollign trollin trolling trolling trolling trollng trollnig troque troubelshooting troubeshooting troublehooting troublehsooting troubleshooing troubleshooitng troubleshootig troubleshootign troubleshootin troubleshooting troubleshooting troubleshooting troubleshootng troubleshootnig troubleshoting troubleshoting troubleshotoing troublesohoting troublesooting troublsehooting troublshooting troulbeshooting trouleshooting trque trubleshooting truobleshooting tsarter tsarters tseting tshiba tsohiba tsting twi twin twin twn twni ty tyeps tyes tyo type types types typs typse u ued uesd uinversal uiversal ulcan uniersal unievrsal univeral univerasl universa universal universal universl universla univesal univesral univresal univrsal unversal unviersal upply urplus us us usd usde use used used uspply usrplus uvlcan vaiable vairable varable varaible variabe variabel variabl variable variable varialbe variale varibale varible vehcile vehcle vehice vehicel vehicl vehicle vehicle vehilce vehile veicle veihcle vheicle vhicle vlcan vlot vlt vlucan vol volt volt vot votl vraiable vriable vucan vuclan vulacn vulan vulca vulcan vulcan vulcn vulcna waehouse waerhouse warehose warehosue warehoue warehoues warehous warehouse warehouse warehuose warehuse wareohuse wareouse warheouse warhouse we weel weg weg weght wegiht wehel weigh weight weight weigt weigth weihgt weiht wesinghouse wesitnghouse westighouse westignhouse westinghose westinghosue westinghoue westinghoues westinghous westinghouse westinghouse westinghuose westinghuse westingohuse westingouse westinhgouse westinhouse westnghouse westnighouse wetinghouse wetsinghouse wg wge whee wheel wheel wheel whel whel whele widing widings widning widnings widnow widow wie wieght wiepr wier wier wight wiing wiirng win windig windign windigns windigs windin winding winding winding windings windings windins windinsg windng windngs windnig windnigs windo window window windw windwo winidng winidngs wining winings winodw winow wipe wiper wiper wipr wipre wir wire wire wirig wirign wirin wiring wiring wirng wirnig wnding wndings wndow wniding wnidings wnidow wok wokr wokrs woks wor work work work works works wors worsk wper wpier wraehouse wre wrehouse wrie wriing wring wrk wrks wrok wroks wsetinghouse wstinghouse wtin ypes ytpes

---