Manager Electrical Maintenance Interview Questions and Answers

REF relay is used for earth fault protection while differential protection relay is used for detecting internal faults.

• REF relay is used to detect earth faults in electrical systems.

• Differential protection relay is used to detect internal faults within electrical equipment.

• REF relay compares the current flowing into and out of the system to detect any imbalance caused by earth faults.

• Differential protection relay compares the current entering and leaving the equipment to dete...read more

The size of power cable for a 55Kw motor depends on factors like voltage, current, and distance.

• The size of the power cable will depend on the voltage and current rating of the motor

• The distance between the motor and the power source will also impact the size of the cable needed

• For a 55Kw motor, typically a cable size of 10mm² to 16mm² may be suitable

Load increase and decrease in generators occur based on the demand for electricity.

• Load increase happens when more electrical appliances are turned on, requiring more power from the generator.

• Load decrease occurs when electrical appliances are turned off, reducing the power demand on the generator.

• Generators adjust their output based on the load changes to maintain a stable power supply.

• Load shedding may be implemented during peak demand to prevent overload on the generator.

• A...read more

Vector shift in power transformers is important for maintaining phase relationship between primary and secondary windings.

• Vector shift helps in maintaining the correct phase relationship between primary and secondary windings of a power transformer.

• It ensures that the transformer operates efficiently and delivers the correct voltage to the load.

• Vector shift is crucial for preventing phase imbalances and ensuring proper functioning of the transformer.

• It is necessary for mainta...read more

Antipumping is a feature in electrical systems to prevent the motor from restarting immediately after a trip.

• Antipumping is a safety feature that prevents the motor from restarting immediately after a trip to avoid damage.

• It is typically used in motor control circuits to ensure proper operation and prevent overload.

• Antipumping can be achieved through the use of interlocking mechanisms or time delay relays.

• For example, in a pump system, antipumping prevents the motor from cont...read more