Question 1

In the Ward Leonard system, a DC shunt generator with field control is driven by a(n) .&#10;A)induction motor&#10;B)transformer&#10;C)precision controller&#10;D)chain drive

Accepted Answer

In the Ward Leonard system, a DC shunt generator with field control is typically driven by an induction motor. This setup allows for precise speed control of the driven machinery, commonly used in applications requiring variable speed control.

Question 2

The generator field resistance can be changed manually or automatically by latching relays.

Accepted Answer

False

Question 3

The field of the DC generator can be reversed manually or automatically with a resulting reversal of the motor rotation.

Accepted Answer

Reversing the field of a DC generator manually or automatically can cause the motor to rotate in the opposite direction. When the field of a DC generator is reversed, the direction of the current flowing through the armature reverses, causing a reversal of the motor rotation. This can be done manually or automatically using a specialized circuit called a reversing switch.

Question 4

Electricity can be generated electromagnetically for heavy power consumption only if the following are present: a magnetic field, a conductor, and the motion of the two.&#10;A)relative&#10;B)down&#10;C)centrifugal&#10;D)up

Accepted Answer

Electromagnetic induction occurs when there is a relative motion between a magnetic field and a conductor. Therefore, the correct choice is A, relative. Electromagnetic induction occurs when there is relative motion between a magnetic field and a conductor, which causes an electric current to flow. The direction of the relative motion (up or down) is not relevant, but it must be present. The other two options (centrifugal and "up") are not relevant to electromagnetic generation of electricity.

Question 5

A controlling tachometer feedback signal may be driven by the DC motor driveshaft.

Accepted Answer

A tachometer feedback signal can be used to monitor the speed of a DC motor and adjust the motor drive to maintain a constant speed. The feedback signal is obtained by measuring the rotational speed of the motor shaft and sending this information back to the motor drive controller. This allows the controller to make precise adjustments to maintain the desired speed, making it a valuable tool in motor control systems. A tachometer feedback signal can be used to monitor the speed of a DC motor. This signal can be generated by connecting a tachometer to the driveshaft of the motor, which will measure the rotational speed and provide a feedback signal to the motor controller. By using this signal, the controller can adjust the motor's speed and maintain a constant level of control over the motor's operation.

Question 6

Some control schemes eliminate the standard exciter and provide other methods of energizing the generator and ____.&#10;A)exciter&#10;B)motor fields&#10;C)remote unit&#10;D)receiving unit

Accepted Answer

Motor fields are energized in some control schemes as an alternative to using a standard exciter, providing the necessary magnetic field for generator operation.

Question 7

Packaged variable speed drives generally operate on AC.

Accepted Answer

Packaged variable speed drives are used to control the speed of AC motors, hence they operate on AC. Packaged variable speed drives commonly operate on AC power.

Question 8

The motor-generator set has one inherent advantage over rectifier-type DC supplies, that is, .&#10;A)the fact of being relocatable&#10;B)being easy to replace when they fail&#10;C)the ability to regenerate&#10;D)being much less expensive

Accepted Answer

The motor-generator set has the ability to regenerate, which means that it can convert mechanical energy back into electrical energy, allowing it to supply power even during power interruptions or power outages. This is not possible with rectifier-type DC supplies, which can only convert AC to DC but cannot regenerate. The motor-generator set has the ability to regenerate, meaning it can recover energy from the load and use it to power other loads. Rectifier-type DC supplies cannot do this. The other options are not necessarily advantages of motor-generator sets over rectifier-type DC supplies.

Question 9

To meet specific operating requirements, the packaged variable-speed control drives can be furnished with a variety of modifications, including provisions for .&#10;A)disc braking&#10;B)reset speed control&#10;C)resistance regulation&#10;D)multimotor drive

Accepted Answer

The answer of To meet specific operating requirements, the packaged...

Question 10

The AC service in industrial plants can not be converted to direct current for use with DC variable-speed controls.

Accepted Answer

AC service can be converted to direct current (DC) using rectifiers, allowing it to be used with DC variable-speed controls in industrial plants.

Deck 57: Dc Variable-Speed Control 14motor Drives