Akhandalamani Electricals & Construction Interview Questions and Answers

Transformers are tested for various parameters to ensure their proper functioning.

• Measurement of winding resistance

• Measurement of voltage ratio and turns ratio

• Measurement of insulation resistance

• Measurement of no-load current and losses

• Measurement of load losses and impedance voltage

• Measurement of temperature rise

• Dielectric tests

PI test is a type of transformer testing that measures the insulation resistance and polarization index.

• PI test is performed to determine the condition of insulation in transformers.

• It involves measuring the insulation resistance and polarization index of the transformer.

• The insulation resistance is measured by applying a DC voltage to the transformer winding and measuring the current.

• The polarization index is the rati...read more

CT Secondary site is shorted to prevent damage to the CT and connected equipment.

• Shorting CT Secondary site prevents high voltage from being induced in the secondary winding.

• It also prevents damage to the CT and connected equipment due to high voltage.

• Shorting is done during CT testing or maintenance.

• Shorting can be done using a shorting link or a shorting switch.

Transformers are rated in KVA because it indicates the maximum amount of power that can be transferred through the transformer.

• KVA rating is used to determine the maximum amount of power that can be transferred through the transformer

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

• KVA rating is important for selecting the appropriate transformer for a given application

• For example, a 100 KVA...read more

Yes, I can draw the control diagram of Star Delta Starter.

• The diagram consists of three contactors, a timer, and an overload relay.

• In the starting position, the contactors are in the open position.

• When the start button is pressed, the timer starts and the contactors close in a specific sequence.

• After a set time, the contactors switch to the delta position.

• The overload relay protects the motor from overloading.

• The contr...read more

VFD stands for Variable Frequency Drive. It is an electronic device used to control the speed and torque of an electric motor.

• VFD works by converting fixed frequency and voltage input into variable frequency and voltage output.

• It uses power electronics to vary the frequency and voltage supplied to the motor, allowing for precise control of motor speed.

• By adjusting the frequency and voltage, VFD can regulate the motor's...read more