Maintenance Electrician Interview Questions and Answers for Freshers

Copper loss or I2R loss depends on current while iron or core loss depends on voltage in transformers.

• Copper loss is the power lost due to the resistance of the copper wire in the transformer winding.

• Iron or core loss is the power lost due to the magnetic properties of the transformer core.

• Higher current leads to higher copper loss while higher voltage leads to higher iron or core loss.

• Efficiency of the transformer can be improved by reducing both copper and iron losses.

A DOL starter is a direct-on-line starter used in electrical systems to start and stop motors.

• DOL stands for Direct-On-Line.

• It is the simplest and most common type of motor starter.

• The DOL starter directly connects the motor to the power supply, providing full voltage at start.

• It consists of a contactor, overload relay, and start and stop buttons.

• When the start button is pressed, the contactor closes and the motor starts.

• The overload relay protects the motor from excessive cu...read more

True, losses in transformers are independent of power factor.

• Transformer losses occur due to core losses and copper losses

• Core losses are constant and independent of load power factor

• Copper losses vary with load but are also independent of power factor

• Power factor affects only the apparent power and not the losses

Transformers are related in kVA because it is a measure of the transformer's capacity to handle electrical load.

• kVA is a measure of the apparent power of a transformer

• It takes into account both the voltage and current of the transformer

• Transformers with higher kVA ratings can handle larger electrical loads

• For example, a 100 kVA transformer can handle more load than a 50 kVA transformer

The unit of specific resistance is ohm-meter (Ω·m).

• Specific resistance is a measure of how strongly a material opposes the flow of electric current.

• It is also known as resistivity.

• The unit ohm-meter represents the resistance between opposite faces of a 1-meter cube of the material.

• Specific resistance depends on the material's composition, temperature, and other factors.