ACME 3L Exam

In the prime mover mode, a negative speed value on the Speed meter in the Metering window indicates that

• the prime mover rotation is in the clockwise direction.

• the prime mover rotation is in the counterclockwise direction.

• the prime mover is supplying torque to drive a load.

• the prime mover is receiving power from a load.

In the prime mover mode, why does the Torque meter in the Metering window indicate a torque value even with no mechanical load applied to the machine's shaft?

• The display is probably defective.

• Because the prime mover must supply torque to overcome friction.

• This indicates the electrical power supplied to the prime mover.

• This indicates the mechanical power supplied to the prime mover.

In the prime mover mode, will the torque indicated by the Torque meter be a negative or positive value for clockwise rotation?

• Negative.

  

• Positive.

• It depends on how fast the prime mover rotates.

• It depends on the value of the applied voltage.

In the brake mode, what does the Torque meter indicate when the torque correction function is disabled?

• The sum of the brake friction torque and belt friction torque.

• The magnetic torque produced by the brake to oppose rotation.

• The torque which the motor coupled to the brake must produce to overcome the magnetic torque.

• The load torque produced by the brake.

When the brake is coupled to a drive motor, what does the Torque meter indicate when the torque correction function is enabled?

• The load torque.

• The sum of the belt friction torque, brake friction torque, and brake magnetic torque

  

• The output torque of the motor coupled to the brake minus the belt friction torque.

• The output torque of the motor coupled by the brake.

What effect does decreasing the field current have on the output voltage of a separately-excited de generator operating at fixed speed?

• The output voltage increases.

  

• The output voltage decreases.

  

• The output voltage oscillates around its original value.

• The value of the field current has no effect on the output voltage.

What effect does increasing the output current have on the input torque of a separately-excited dc generator?

• The torque increases.

  

• The torque decreases.

• The torque oscillates around its original value.

• The value of output current has no effect on the torque.

What is the main characteristic of a cumulative compound generator?



• The output voltage becomes unstable when the output current decreases.

• The output voltage decreases when the output current increases.

• The output voltage increases when the output current increases.

• The output voltage varies little when the output current varies.

What is the main characteristic of a differential compound generator?



• The output voltage becomes unstable when the output current decreases.

• The output voltage decreases fairly rapidly when the output load current increases.

• The output voltage increases when the output current increases.

• The output voltage is made independent of the output current.

What happens when the field current of a separately-excited de generator is increased and the speed is maintained constant?

• The output current decreases.

  

• The output voltage increases.

• The output voltage decreases.

• The output voltage is independent of the field current.