National Fertilizers Electrical Engineer Interview Questions and Answers

Starters are used to control the starting and stopping of motors. Types include DOL, star-delta, soft starters, and VFDs.

• Direct-On-Line (DOL) starters provide full voltage to the motor at start-up

• Star-Delta starters reduce the voltage during start-up to reduce inrush current

• Soft starters gradually increase the voltage to the motor to reduce inrush current and mechanical stress

• Variable Frequency Drives (VFDs) control th...read more

The 3 tier breaker interlock scheme is used to ensure safe and efficient power distribution from different sources.

• The scheme involves three levels of protection to prevent power overload and equipment damage.

• The first tier involves interlocking the main breaker with the emergency stop button to quickly shut off power in case of an emergency.

• The second tier involves interlocking the main breaker with the VFD and starte...read more

Transformers work on the principle of electromagnetic induction to transfer electrical energy between two or more circuits.

• Transformers have two coils of wire, known as primary and secondary coils, which are wound around a core made of ferromagnetic material.

• When an alternating current flows through the primary coil, it creates a changing magnetic field around the coil.

• This changing magnetic field induces a voltage in ...read more

Transformers are cooled using methods such as oil cooling, air cooling, and water cooling.

• Oil cooling: Transformers are immersed in oil to dissipate heat generated during operation.

• Air cooling: Fans are used to circulate air around the transformer to cool it down.

• Water cooling: Water is circulated around the transformer to absorb heat and cool it.

• Forced oil cooling: Oil is circulated through a heat exchanger to remove