Maintenance and Troubleshooting for Wound-Rotor Induction Motors

Question 1

What sort of symptoms might you expect if an open occurs in the secondary circuit of a wound-rotor motor?

Answer 1

Failure of the motor to start, or the motor turns slowly

Question 2

Where might the open in the secondary circuit of a wound-rotor motor occur?

Answer 2

in the rotor, at the brushes and slip rings, in the controller, in the resistor bank, or in the connections between these parts

Question 3

If the manufacturer’s specifications for brush pressure are not available, what is a safe rule to use?

Answer 3

two pounds per square inch or 1.38kPa

Question 4

Is it better to have the brush pressure too high or too low?

Answer 4

Too high is better than too low

Question 5

When should a brush be replaced?

Answer 5

When the brush is down to about one-quarter of its original length

Question 6

If a wound-rotor motor is connected up and runs with the wrong rotation, how do you remedy this situation?

Answer 6

Interchange any two of the line leads to the stator