What are basic requirements of protective relaying?

Fundamental Requirements of Protective Relay:

• Selectivity.
• Speed.
• Sensitivity.
• Reliability.
• Simplicity.
• Economy.

How do protective relaying operates?

Protective relay work as a sensing device, it senses the fault, then known its position and finally, it gives the tripping command to the circuit breaker. The relay must come into action whenever there is a fault and must not operate if there is no fault. Some relays are used for the protection of the power system.

What is protection relay function?

The purpose of the protection relay is to detect a problem, ideally during its initial stage, and to either eliminate or significantly reduce damage to personnel and/or equipment.

What is protective relaying what is the need for protective relaying?

Relays detect and locate faults by measuring electrical quantities in the power system which are different during normal and intolerable conditions. The most important role of protective relaying is to first protect individuals, and second to protect equipment.

What is the function of a protective relay?

•The function of protective relaying is to cause the prompt removal from service of an element of a power system when it suffers a short circuit or when it starts to operate in any abnormal manner that might cause damage or otherwise interfere with the effective operation of the rest of the system.

What is drop out ratio of protective relays?

Drop out protective relaying of utility-consumer interconnections) Contact operation (opening or closing) as a relay just departs from pickup. The value at which dropout occurs is usually stated as a percentage of pickup. For example, dropout ratio of a typical instantaneous overvoltage relay is 90 percent.

What is the definition of a distance relay?

distance relay (1) A generic term covering those forms of protective relays in which the response to the input quantities is primarily a function of the electrical circuit distance between the relay location and the point of fault.

How are distance relays used to protect transmission lines?

Transmission lines can be protected by several types of relays, however the most common practice to protect transmission lines is to equip them with distance relays. Distance relays are designed to respond change in current, voltage, and the phase angle between the measured current and voltage.