Question 1

The slip rings permit the connection of external resistance to the rotor windings.

Accepted Answer

Slip rings are electrical contacts that allow external devices, such as resistors, to be connected to the rotor windings of an electric motor or generator. This can be useful for controlling the speed or torque of the motor, among other applications. Therefore, the statement is true.

Question 2

Testing the rotor of a wound rotor motor is very similar to testing the stator.

Accepted Answer

Testing the rotor of a wound rotor motor involves using techniques such as a growler test or a bar-to-bar test, similar to testing the stator.

Question 3

An advantage of the wound rotor motor is its high starting torque.

Accepted Answer

The wound rotor motor has a high starting torque due to the adjustable resistance in the rotor circuit which allows for a smoother start-up and gradual acceleration.

Question 4

The rotor of the wound rotor induction motor contains ____.&#10;A) squirrel-cage bars&#10;B) stator laminations&#10;C) commutator segments&#10;D) wound coils of wire

Accepted Answer

The rotor of the wound rotor induction motor contains wound coils of wire, which allows for external resistance to be added, thus improving starting torque and controlling speed. It does not contain squirrel-cage bars, stator laminations, or commutator segments.

Question 5

A type of ____ induction motor used for operating large air conditioning units is the wound rotor induction motor.&#10;A) switched reluctance&#10;B) three-phase&#10;C) stepper&#10;D) universal

Accepted Answer

The best choice is B, three-phase, as this is the type of motor commonly used in large AC units. While switched reluctance, stepper, and universal motors can also be used for various applications, they are not typically used for operating air conditioning units. Wound rotor induction motors are a type of three-phase motor that is best suited for high power applications where precise control of speed is required.

Question 6

Most large wound rotor motors use a method of ____ as opposed to actual variable resistors.&#10;A) full voltage starting&#10;B) soft starting&#10;C) step starting&#10;D) reduced voltage starting

Accepted Answer

Most large wound rotor motors use step starting, which involves gradually increasing the resistance in the rotor circuit to control the starting current and torque, rather than using actual variable resistors.

Question 7

The stator winding of the wound rotor induction motor is different from the stator of a squirrel-cage induction motor.

Accepted Answer

The stator winding of both the wound rotor induction motor and the squirrel-cage induction motor is essentially the same, designed to produce a rotating magnetic field.

Question 8

In a wound rotor induction motor, resistance is connected to the slip rings by means of ____.&#10;A) brush holders&#10;B) klixons&#10;C) carbon brushes&#10;D) external resistors

Accepted Answer

Carbon brushes are used to connect the resistance to the slip rings in a wound rotor induction motor, allowing for control of the motor's characteristics.

Question 9

There is a single control method used to short out the steps of resistance when starting a wound rotor motor.

Accepted Answer

There are multiple methods to short out the steps of resistance when starting a wound rotor motor, including using an external resistance bank that is gradually shorted out, not just a single method.

Question 10

A great advantage of the wound rotor motor is that it limits the amount of inrush current ____ the motor is first started.&#10;A) when&#10;B) before&#10;C) after&#10;D) periodically after

Accepted Answer

The wound rotor motor has a special feature of adjustable resistance in its rotor circuit, which limits the amount of inrush current when the motor is first started. This helps in preventing damage to the motor and the connected equipment. Therefore, the correct choice is A - when.

Deck 16: The Wound Rotor Induction Motor