Interview Questions and Answers

Protection against Over voltages due to Lightning Interview Questions and Answers: 1. What is meant by voltage surge ? Ans. By voltage surge is meant any sudden excessive rise in voltage that may be dangerous to the electrical equipment of an installation. 2. What are the internal causes of overvoltages ? Ans. Internal overvoltages arise […]

Protection of Feeders and Transmission Lines Interview Questions and Answers: 1. What is unit type protection ? Ans. Unit system of protection is one in which the protection responds to faults in the protected zone alone and it does not respond to through faults (faults beyond the protected zone). Non-unit systems do not have exact

Bus Bar Protection Interview Questions and Answers: 1. Why use of single bus-bar arrangement is restricted to small and medium sized substations and small power stations ? Ans. The glaring drawback of this system is that in case of fault on the bus-bars, whole of the supply is affected and all the healthy feeders are

Transformer Protection Interview Questions and Answers: 1. What are the faults that are likely to occur in a power transformer ? Ans. The faults likely to occur in a power transformer are open-circuit faults (an open circuit in one phase of a 3-phase transformer), earth faults, phase-to-phase faults, inter-turn faults and overheating. 2. What are

Protection of AC Generators and Motors Interview Questions and Answers: 1. What are the common types of generator faults ? Ans. The common types of faults occurring in synchronous generators are enumerated below. Stator winding faults — phase-to-phase faults, phase-to-earth faults and inter-turn faults. Rotor winding faults — conductor-to-earth faults, open-circuit faults, inter-turn faults. The

Static Relays Interview Questions and Answers: 1. What is static relay ? Ans. A static relay refers to a relay in which there is no armature or other moving element and response is developed by electronic, magnetic or other components without mechanical motion. A relay using combination of both static and electromagnetic units is also

Protective Relays Interview Questions and Answers: 1. What is a protective relay ? Ans. Protective relay is an electrical device designed to initiate isolation of a part of an electrical installation, or to operate an alarm signal, in the event of an abnormal condition or a fault. 2. What are the functions of a protective

Circuit Breakers Interview Questions and Answers: 1. What do you understand by switchgear ? Ans. The apparatus employed for switching, controlling and protecting the electrical circuits and equipment is known as switchgear. 2. Which of the gases are employed in commercial gas-blast circuit breakers ? Ans. SF6 and air are used in commercial gas-blast circuit

Circuit Breaking Interview Questions and Answers: 1. What is a circuit breaker ? Ans. Circuit breaker is a mechanical device designed to close or open contact members, thus closing or opening an electrical circuit under normal or abnormal conditions. 2. How does a circuit breaker differ from a switch ? Ans. A circuit breaker is

Fuses Interview Questions and Answers: 1. What is meant by a fuse ? Ans. Fuse is a device used in an electrical circuit for protecting electrical equipment’s against overloads and/or short circuits. 2. On what principle does the fuse operate ? Ans. The action of a fuse is based upon the heating effect of the