Question 1

An automatic synchronous motor starter can be used with a synchronous motor to provide automatic control of the startup sequence.

Accepted Answer

An automatic synchronous motor starter can be used with a synchronous motor to provide automatic control of the startup sequence. An automatic synchronous motor starter is designed to control the timing and sequence of the startup process for a synchronous motor, making it an ideal choice for applications where precise control is required. This type of starter is capable of automatically adjusting the motor's speed and load to match the requirements of the application, ensuring that the motor is operating at peak efficiency and performance. This makes it a valuable tool for a wide range of industrial and commercial applications, from manufacturing and production to power generation and distribution.

Question 2

The squirrel cage winding will overheat if a synchronous motor starts, accelerates, and reaches synchronous speed within a time interval determined to be normal for the motor.

Accepted Answer

The squirrel cage winding will not overheat if a synchronous motor starts, accelerates, and reaches synchronous speed within a time interval determined to be normal for the motor because there is no current flowing through it during this process.

Question 3

A synchronous motor is started by accelerating the motor to as high a speed as possible from the squirrel cage winding and then applying the DC field excitation.

Accepted Answer

A synchronous motor is indeed started by first accelerating it to a high speed using its squirrel cage winding (if it has one, acting similarly to an induction motor), and then applying the DC field excitation to pull it into synchronization with the supply frequency. This method helps the motor overcome initial inertia and reach a speed close to its synchronous speed before synchronization.

Question 4

The coil of the field contactor is operated from the same direct-current source that provides excitation for the .&#10;A)AC field winding&#10;B)low inductive circuit&#10;C)dynamic magnetic field&#10;D)synchronous motor field

Accepted Answer

The coil of the field contactor is operated from the same direct-current source that provides excitation for the synchronous motor field. This ensures that the contactor operates in sync with the motor's requirements for excitation current.

Question 5

In the brushless DC exciter, the commutator of a conventional direct-connected exciter is replaced with a three- phase, bridge-type, .&#10;A)solid-state rectifier&#10;B)controlled rectifier&#10;C)direct transformer&#10;D)small rectifier

Accepted Answer

The commutator of a conventional exciter is replaced with a solid-state rectifier in a brushless DC exciter. A solid-state rectifier is used to replace the commutator in a brushless DC exciter. This allows for more efficient and reliable operation compared to a conventional direct-connected exciter.

Question 6

There are three basic methods of starting synchronous motors automatically.

Accepted Answer

There are several methods to start synchronous motors, but they are not limited to just three. Common methods include using an induction motor start, a pony motor, or a variable frequency drive.

Question 7

A solenoid-operated field contactor is similar in appearance to the standard contactor.&#10;A)magnetic&#10;B)AC&#10;C)DC&#10;D)polarized

Accepted Answer

The answer of A solenoid-operated field contactor is similar in...

Question 8

The development of the brushless DC exciter is an improvement in synchronous motor excitation.

Accepted Answer

The statement is true. The brushless DC exciter is an improvement in synchronous motor excitation technology. It eliminates the need for brushes and slip rings, reducing maintenance and increasing efficiency. The brushless DC exciter eliminates the need for brushes and commutators, resulting in a more efficient and reliable excitation system for synchronous motors.

Question 9

The field contactor opens to the source of excitation.&#10;A)the top line&#10;B)both lines&#10;C)the second line&#10;D)either of the two lines

Accepted Answer

The field contactor opens both lines to the source of excitation to ensure complete disconnection and safety.

Question 10

If the synchronous motor operates at subsynchronous speed, the squirrel cage winding may and be damaged.&#10;A)subcool&#10;B)restart&#10;C)overheat&#10;D)reset

Accepted Answer

Operating a synchronous motor at subsynchronous speed will cause the rotor to rotate at a speed slower than the stator's rotating magnetic field. This will cause the rotor to generate a torque in the opposite direction, creating a backward force. The backward force can cause the rotor to overheat and damage the squirrel cage winding. If the synchronous motor operates at subsynchronous speed, the rotor will experience excessive currents and may overheat, causing damage to the squirrel cage winding.

Deck 42: Synchronous Automatic Motor Starter