Protective relays are one of the critical components of the electrical power grid that serve to detect defective equipment or other dangerous or intolerable conditions and can either initiate or permit switching or simply provide an alarm to provide a safer, more reliable delivery system.
What do protective relays provide Mcq?
ANSWER: b. Close the contacts when the actuating quantity attains a certain predetermined value.
What is meant protective relay?
In electrical engineering, a protective relay is a relay device designed to trip a circuit breaker when a fault is detected. … Important transmission lines and generators have cubicles dedicated to protection, with many individual electromechanical devices, or one or two microprocessor relays.
Why is a relay used in a circuit?
Relays control one electrical circuit by opening and closing contacts in another circuit. … Relays are generally used to switch smaller currents in a control circuit and do not usually control power consuming devices except for small motors and Solenoids that draw low amps.
What is the function of relay Mcq?
The function of a relay is to
Detect fault. Interrupt circuit. Detect and interrupt.
What are the essential elements of a protective relay?
What are the Essential Qualities of Protective Relay?
- Speed and Time.
- Selectivity and discrimination.
What is MHO relay?
Mho relay is a voltage restrained directional relay. Important Points: Reactance relay is suitable for the protection of a short transmission line because its operation is independent of arc resistance. The relay which is selected for a long transmission line should be less affected due to power swings.
What are the basic requirement of protective relay?
Fundamental Requirements of Protective Relay:
Selectivity. Speed. Sensitivity. Reliability.
What is the main function of relay?
A relay allows circuits to be switched by electrical equipment: for example, a timer circuit with a relay could switch power at a preset time. For many years relays were the standard method of controlling industrial electronic systems.
What is a relay used in?
Relays are used to control high voltage circuits with the help of low voltage signals. Similarly they are used to control high current circuits with the help of low current signals. They are also used as protective relays. By this function all the faults during transmission and reception can be detected and isolated.
Is relay a sensor?
The term “relay” is usually called a variety of devices, the switching contacts in response to a change in some input variable, not necessarily electric. … In fact it is the sensors that are connected to the relay and interacting with them according to a specific algorithm.
How the protective relays are classified based on their technology?
Types of protection relays are mainly based on their characteristic, logic, on actuating parameter and operation mechanism. Based on operation mechanism protection relay can be categorized as electromagnetic relay, static relay and mechanical relay.
Which type of relay is used for protection of transmission line?
Introduction. A distance relay is a type of protection relay most often used for transmission line protection. Distance relays measure the impedance from the installation side to the fault location and operates in response to changes in the ratio of measured current and voltage.
Which two are contradictory attributes of a good protective relay?
Such an essential qualities of protective relaying are: Reliability, Selectivity and Discrimination, Speed and Time, Sensitivity, Stability, Adequateness, Simplicity and Economy.