Question 1

Pilot control devices are often employed to control the operation of a wound rotor induction motor.

Accepted Answer

Pilot control devices, such as resistors, rheostats, and capacitors, are often used to control the speed and torque of a wound rotor induction motor. Pilot control devices such as resistors, switches, and rheostats are commonly used to control the speed and torque of a wound rotor induction motor.

Question 2

The overload relay for a wound rotor motor contains two sets of contacts, both normally closed.

Accepted Answer

An overload relay typically has one set of normally closed contacts that open to stop the motor in the event of an overload, not two sets of normally closed contacts.

Question 3

Current transformers sense motor current and supply current to the____________ .

Accepted Answer

Current transformers are used to sense motor current and supply current to overload heaters, which protect motors from overheating by tripping the circuit if the current exceeds a certain level.

Question 4

A(n) ______________indicates when power is supplied to the control circuit.

Accepted Answer

A green pilot lamp is typically used to indicate when power is supplied to the control circuit. A green pilot lamp typically indicates when power is supplied to the control circuit. An audible alarm indicates an alarm condition, a flashing LED typically indicates a fault or error, and a red warning lamp indicates a warning or critical alarm condition.

Question 5

Four separate levers permit selection of the motor's operating speed.

Accepted Answer

This statement is false. Levers do not typically control a motor's operating speed, but rather the direction or on/off functionality. A motor's speed is usually controlled through a separate speed control device, such as a variable frequency drive or a motor starter with adjustable speed settings. This statement is not enough to determine the validity of the statement. The context and details of the motor's design would need to be known to confirm or refute this statement.

Question 6

If the motor is operating and a lower speed is selected, it immediately decreases to the lower speed without time
delay.

Accepted Answer

When a lower speed is selected while the motor is operating, it immediately decreases to the lower speed without any time delay. When the lower speed is selected while the motor is operating, it should immediately decrease to the lower speed without any delay.

Question 7

If the motor is operating at a low speed and a higher speed is selected, the motor immediately increases to the next higher speed if it has been operating in its present speed for more than____________ .

Accepted Answer

The motor increases to the next higher speed immediately if it has been operating in its present speed for more than 3 seconds. The question states that if the motor has been operating at a low speed and a higher speed is selected, then the motor immediately increases to the next higher speed if it has been operating in its present speed for more than 3 seconds. Therefore, choice A is correct. Choices B, C, and D are incorrect as they all suggest longer periods of time than 3 seconds.

Question 8

The normally closed set of the overload relay is connected in parallel with float switch EFS and will active the red warning lamp and alarm in the event of________________ .

Accepted Answer

The normally closed set of the overload relay is designed to open in the event of a motor overload, which would then activate the red warning lamp and alarm as part of a protective response.

Quiz 37: Automatic Speed Control for Wound Rotor Motors