Electric Motor Presentation

7/29/2019 Electric Motor Presentation

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Electric Motors


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Electric Motor

Converts electricity into mechanical motion

Works by electromagnetism

Lorentz Force Law

Current flowing through a

wire produces a magneticfield (labeled M here) around

the wire.


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Simple DC Motor

Armature or rotor

Commutator

Brushes Axle

Field magnet

DC power supply


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Simple DC Motor

A magnetic field is generatedaround the armature.

The left side of the armature ispushed away from the leftmagnet and drawn toward the

right, causing rotation. When the armature becomeshorizontally aligned, thecommutator reverses thedirection of current through thecoil, reversing the magneticfield.

Momentum keeps the motormoving the right direction.

The process then repeats.


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3 Pole Motor

A motor can have any

number of poles

Most common form

Doesnt get stuck inhorizontal position

In 2 pole, always

shorts out the batterywhen the commutator

flips the field


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Examples of everyday motors

EVERYTHING!!!!!

At home:

The fan over the stove and in the microwave oven The dispose-all under the sink The blender The can opener The refrigerator- Two or three in fact:

one for the compressor, one for the fan inside the refrigerator, as well as one in the icemaker

The mixer The tape playerin the answering machine Probably even the clock on the oven The washer The dryer The electric screwdriver The vacuum cleanerand the Dustbuster mini-vac

The electric saw The electric drill The furnace blower Even in the bathroom, there's a motor in:

The fan The electric toothbrush The hair dryer The electric razor

Your car is loaded with electric motors:

Power windows (a motor in each window) Power seats (up to seven motors per seat) Fans for the heater and the radiator Windshield wipers The starter motor Electric radio antennas

Motors in all sorts of places:

YouriPod Several in the VCR Several in a CD playeror tape deck Many in a computer Most toys that move

Electric clocks The garage door opener Aquarium pumps


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Motor efficiency matters

In Industry, electric motors consume:

~680 billion kWh/year

~63% of all industrial electricity consumption

~23% of all consumption

These percentages are typically higher in

developing countries, while the motors are

typically less efficient


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How is powerlostin a motor?

Mechanical (friction and windage) losses friction in bearings and seals and power consumed by

the motor cooling fan

Magnetic (core) losses hysteresis and eddy current losses in steel

laminations of the stator and rotor

Electrical (I2R) losses Stator winding losses

Rotor conductor bar losses

Stray losses miscellaneous losses associated mainly with

electromagnetic radiation


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U.S. standard for determination

of motor efficiency: IEEE 112-B

Based on Energy Policy Act legislation

(The value of efficiency is then normally converted from a decimal fraction to a percent for convenience.)

Need for a standard:

Efficiency changes as grease breaks in

Output and input power can vary

Readings of speed, torque, volts, amperes, watts are

not steady of constant values


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Overview of motor efficiencies

The following table of results from three different

testing standards:

Test Method 15 HP 75 HP 800 HP 1500 HP

IEEE 112 B (U.S.) 87.4 90.0 95.9 95.9

IEC 34-2 (International) 89.2 92.7 95.6 96.0

JEC 37 (Japanese) 90.1 93.1 95.9 96.8


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Improving motor efficiencies

According to U.S. DOE, use of only PremiumEfficiency motors could save ~20 billion

kWh/year in the U.S.

Covers wide-range of motor specifications

680 billion kWh/year consumption by electric motors

Joint specification by:

National Electrical Manufacturers Association(NEMA )

Consortium for Energy Efficiency (CEE)


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NEMA Premium motors

Example One50 hp, 1800 rpm,460 V

Example Two25 hp, 1800 rpm,460 V

EPAct Standard NEMA Premium EPAct StandardNEMAPremium

Full Load Efficiency 93.1* 94.5 92.4 93.6

Efficiency (at 75%

load) 93.6 95.1 93.1 94.1

Demand Reduction(at 75% load)

- 0.47 kW - 0.16 kW

Meets EPAct? yes yes yes yes

Incremental MotorCost - $176 - $96

Energy Savings at75% Load (6000hrs/year)

- 2,829 kWh/y - 958 kWh/y


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Expanding the definition of motor

Solar powered nano motor

The Future


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Thank you.The end.


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Background: AC Induction Motor

This is the most commonplace motor. It has arotating stator field. The rotor has imbedded

electroconductive bars resembling a pet rodent

exercise wheel, which inspired the name, squirrel

cage. The rotating stator field induces current in the

cage creating a magnetic field which causes the rotor

to follow the stator field.

First Induction

Motor, 1888

Inventor NikolaTesla

1894 InductionMotor. Worlds

largest when

new. 65 HP


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How is efficiency determined?

IEEE 112-B (United States)

IEC IEC60034.2 (International ElectrotechnicalCommission)

JEC-37 (Japanese Electrotechnical Committee)

C-390 (Canadian Standards Association)

There are different standards in usearound the world for the

determination of motor efficiency.

They yield slightly different results.


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Whats in an efficient motor?

Same components; just more and bettermaterials and closer tolerances.

Larger wire gage Lower stator winding

loss

Longer rotor and stator Lower core

lossLower rotor bar resistance Lower rotor

loss

Smaller fan Lower windage loss

Optimized air gap size Lower stray

load loss

Better steel with thinner laminations --

Lower core loss

Optimum bearing seal/shield Lower

friction loss


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A Useful Tool MotorMaster+

Compare:Motors of varying eff.

Repair vs. replace

>25,000 motors indatabase

Calculate energy

savings

Calculate LCC


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A New Tool MotorMaster+ International

Includes IEC motors

English, Spanish, &

French modes

Accomodates several

currencies

Documents

Electric Motor Presentation