Question

When a motor application requires a motor to be cycled often, what two rated specifications on the motor nameplate should be increased from the normal rating?

a) Voltage and current
b) Power factor and efficiency
c) Frequency and speed

Answer 1

For motor applications with frequent cycling, the duty cycle and the service factor on the motor nameplate should be increased to ensure reliability and handle occasional overloads.

Step-by-step explanation:

When a motor application requires a motor to be cycled often, the two ratings on the motor nameplate that should be increased from the normal rating are the duty cycle and the startup current capacity or the service factor.

Increasing the duty cycle ensures the motor can handle the frequent starts and stops without overheating.

A higher service factor allows the motor to handle occasional overloads without damage, which can occur during repeated cycling.

Unlike the duty cycle and service factor, other specifications such as voltage and current are not necessarily increased because the motor still needs to match the power supply and load requirements.