R R GROUP Interview Questions and Answers

A circuit breaker is an electrical switch that automatically interrupts an electrical circuit when it detects a fault.

• It is used to protect electrical equipment from damage caused by overcurrent or short circuit.

• It works by detecting the abnormal current flow and interrupting the circuit to prevent further damage.

• There are different types of circuit breakers such as thermal, magnetic, and hybrid.

• Examples of circuit bre...read more

Transformer protection system is a set of devices and techniques used to protect transformers from damage.

• It includes devices like Buchholz relay, differential relay, and overcurrent relay.

• The system detects faults and isolates the transformer from the network to prevent further damage.

• It also includes techniques like oil level monitoring and temperature monitoring.

• The protection system is essential for ensuring the re...read more

A relay is an electrically operated switch that uses an electromagnet to mechanically control the switching action. CB stands for Circuit Breaker, which is an automatic electrical switch designed to protect an electrical circuit from damage caused by overload or short circuit.

• Relay is an electrically operated switch

• It uses an electromagnet to control the switching action

• CB is short for Circuit Breaker

• Circuit Breaker pr...read more

Humming effect is a low-frequency noise produced by electrical equipment or machinery.

• It is caused by the vibration of the equipment or machinery.

• It can be a sign of a problem with the equipment or machinery.

• It can be reduced by proper maintenance and lubrication.

• Examples include transformers, motors, and generators.

• It can also be caused by electrical interference from other equipment or sources.

For 1.5 HP to 20 HP motors, Direct-On-Line (DOL) starters are commonly used.

• Direct-On-Line (DOL) starters are suitable for motors up to 20 HP.

• DOL starters provide a simple and cost-effective method of starting motors.

• For motors below 5 HP, a single-phase DOL starter can be used.

• For motors above 5 HP, a three-phase DOL starter is typically used.

• DOL starters directly connect the motor to the power supply, providing full ...read more

An isolator is an electrical switch used to isolate a circuit from the power source. There are different types of isolators.

• Isolators are used to disconnect a circuit from the power source for maintenance or repair.

• They are also used for safety purposes to prevent electrical shocks.

• Types of isolators include load break isolators, pantograph isolators, and center break isolators.

• Load break isolators are used for low vol...read more