Types of Protection System?

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•Protection systems can be classified into two categories:

•apparatus protection; and system protection .

•Apparatus Protection :

Apparatus protection deals with detection of a fault in the apparatus and consequent protection. Apparatus protection can be further classified into following:

–- Transmission Line Protection and feeder protection

–- Transformer Protection

–- Generator Protection

–- Motor Protection

–- Bus-bar Protection.

•System Protection :

–System protection deals with detection of proximity of system to unstable operating region and consequent control actions to restore stable operating point and/or prevent damage to equipments. Loss of system stability can lead to partial or complete system blackouts. Under-frequency relays, out-of-step protection, is-landing systems, rate of change of frequency relays, reverse power flow relays, voltage surge relays etc are used for system protection. Wide Area Measurement (WAM) systems are also being deployed for system protection. Control actions associated with system protection may be classified into preventive or emergency control actions.

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