Protective Relays

Types of Protection

Types of Protection: When a fault occurs on any part of electric power system, it must be cleared quickly in order to avoid damage and/or interference with the rest of the system. It is a usual practice to divide the Types of Protection scheme into two classes viz. primary protection and back-up protection. 1. Primary …

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Translay System

Translay System: This system is the modified form of voltage-balance system. Although the principle of balanced (opposed) voltages is retained, it differs from the above voltage-balance system in that the balance or opposition is between voltages induced in the secondary coils wound on the relay magnets and not between the secondary voltages of the line …

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Differential Relay

Differential Relay: Most of the relays discussed so far relied on excess of current for their operation. Such relays are less sensitive because they cannot make correct distinction between heavy load conditions and minor fault conditions. In order to overcome this difficulty, differential relay are used. A differential relay is one that operates when the …

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Relay Timing Circuit

Relay Timing Circuit: An important characteristic of a relay is its time of operation. By the Relay Timing Circuit of operation is meant length of the time from the instant when the actuating element is energized to the instant when the relay contacts are closed. Sometimes it is desirable and necessary to control the operating …

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Basic Relays

Basic Relays: Most of the Basic Relays used in the power system operate by virtue of the current and/or voltage supplied by current and voltage transformers connected in various combinations to the system element that is to be protected. Through the individual or relative changes in these two quantities, faults signal their presence, type and …

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