UTILITY PROJECTS AND SERVICES Interview Questions, Process, and Tips

Star delta contactors are used in electrical systems to control the starting and stopping of three-phase motors.

• Star delta contactors are used to reduce the starting current of three-phase motors.

• They are commonly used in industrial applications where large motors are used.

• The contactors switch the motor windings from a star configuration to a delta configuration.

• This reduces the voltage across each winding and limits ...read more

There are two main types of motors: AC motors and DC motors.

• AC motors: synchronous and asynchronous

• DC motors: brushed and brushless

• Other types: stepper motors, servo motors, linear motors

• Motors can also be classified by their power source, size, and application

APFC panel is used in industries to improve power factor and reduce energy consumption.

• APFC panel helps in maintaining a high power factor which reduces energy consumption and saves money.

• It also helps in reducing voltage drops and improves the efficiency of electrical equipment.

• APFC panel is commonly used in industries with high power consumption such as steel plants, cement factories, and chemical plants.

• It can also ...read more

There are several types of motor protection relays used in electrical systems.

• Motor overload protection relays

• Motor thermal protection relays

• Motor phase loss protection relays

• Motor short circuit protection relays

• Motor underload protection relays

• Motor earth fault protection relays

• Motor stall protection relays

Types of compressors include reciprocating, rotary screw, centrifugal, and scroll compressors.

• Reciprocating compressors use pistons to compress air.

• Rotary screw compressors use two rotating screws to compress air.

• Centrifugal compressors use a rotating impeller to compress air.

• Scroll compressors use two interleaving scrolls to compress air.

Types of chillers include air-cooled, water-cooled, and absorption chillers. Cooling towers can be classified as mechanical draft or natural draft.

• Air-cooled chillers use air to remove heat from the refrigerant.

• Water-cooled chillers use water to remove heat from the refrigerant.

• Absorption chillers use a heat source to drive the refrigeration cycle.

• Mechanical draft cooling towers use fans to move air through the tower.

• N...read more

Air cooled chillers use air to remove heat from the refrigerant, while water cooled chillers use water for the same purpose.

• Air cooled chillers have condensers that use ambient air to cool the refrigerant, while water cooled chillers have condensers that use water from a cooling tower or a closed loop system.

• Air cooled chillers are typically easier to install and maintain compared to water cooled chillers.

• Water cooled ...read more