Product Manual

For easy reference, standard NEMA service factors for various horse-

power motors and motor speeds are shown in this table.

The NEMA service factor for totally enclosed motors is 1.0. However, many

manufacturers build TEFC with a 1.15 service factor.

Capacitors

Capacitors are used on all fractional HP induction motors except

shaded-pole, split-phase and polyphase. Start capacitors are designed

to stay in circuit a very short time (3-5 seconds), while run capacitors are

permanently in circuit. Capacitors are rated by capacity and voltage.

Never use a capacitor with a voltage less than that recommended with

the replacement motor. A higher voltage is acceptable.

Efficiency

A motor’s efficiency is a measurement of useful work produced by

the motor versus the energy it consumes (heat and friction). An 84%

efficient motor with a total watt draw of 400W produces 336 watts of

useful energy (400 x .84 = 336W). The 64 watts lost (400 - 336 = 64W)

becomes heat.

Encoders

Encoders are devices that translate a signal, whether motion into posi-

tion or velocity feedback for a motion control system. Take a conveyor

system as an application. You want to run the conveyor at 100 feet per

minute. The motor that powers this conveyor has an encoder mounted

to its shaft. Output from the encoder goes into the controller and as

long as the output signal is telling the controller that everything is fine

– the motor is running at the correct speed - it continues running at

the current speed. If the load on the conveyor changes, like it is being

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FOR DRIP PROOF MOTORS

Service Factor Synchronous Speed (RPM)

HP 3600 1800 1200 900

1.35 1.35 1.35 1.35

1.25 1.25 1.25 1.25

1.25 1.25 1.15 1.15

1 1.25 1.15 1.15 1.15

up 1.15 1.15 1.15 1.15