Question 1

Slip rings are usually made of
A)carbon or graphite
B)brass or steel
C)silver or gold
D)copper or aluminium

Accepted Answer

Slip rings are typically made of materials that have good electrical conductivity and resistance to wear and corrosion, which makes brass or steel common choices. These materials ensure a reliable electrical connection and durability in various applications, including electric motors and generators.

Question 2

An over excited synchronous motor is used for
A)fluctuating loads
B)variable speed loads
C)low torque loads
D)power factor corrections

Accepted Answer

An over excited synchronous motor operates at a leading power factor, which makes it suitable for power factor correction in electrical systems.

Question 3

When the voltage applied to a synchronous motor is increased, which of the following will reduce ?
A)Stator flux
B)Pull in torque
C)Both (a) and (b)
D)None of the above

Accepted Answer

Increasing the voltage applied to a synchronous motor does not reduce the stator flux or the pull-in torque. Instead, increasing the voltage typically increases the magnetic flux in the motor, which can lead to an increase in the pull-in torque, assuming other factors such as the motor's load and power factor are constant.

Question 4

The efficiency of a properly designed synchronous motor will usually fall in range
A)60 to 70%
B)75 to 80%
C)85 to 95%
D)99 to 99.5%

Accepted Answer

Synchronous motors, when properly designed, are highly efficient machines. Their efficiency typically ranges from 85 to 95%, depending on factors such as size and operating conditions.

Question 5

To limit the operating temperature an electrical machine should have proper
A)voltage rating
B)current rating
C)power factor
D)speed

Accepted Answer

The current rating is crucial for limiting the operating temperature of an electrical machine, as excessive current can lead to overheating.

Quiz 4: Synchronous Motor Characteristics and Applications

Slip rings are usually made of

An over excited synchronous motor is used for

When the voltage applied to a synchronous motor is increased, which of the following will reduce ?

The efficiency of a properly designed synchronous motor will usually fall in range

To limit the operating temperature an electrical machine should have proper