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ABOUT ELECTRICAL TRANSMISSION LINE DIFFERENTIAL PROTECTION

LINE  DIFFERENTIAL  PROTECTION

Many transmission lines are now having OPGW or separate optic fiber laid for the communication. Where ever such facilities are available, it is recommended to have the line differential protection as Main-I protection with distance protection as backup (built-in Main relay or standalone). Main-II protection shall continue to be distance protection. For cables and composite lines, line differential protection with built in distance back up shall be applied as Main-I protection and distance relay as Main-II protection. Auto-reclose shall be blocked for faults in the cables.

For Lines with length smaller than 10KMs having OPGW Communication link availability, shall have Line Differential Protection as both Main-1 and Main-2 and Distance Protection as backup function in both relays.

·       Current differential protection with line charging compensation.

·       Inbuilt distance protection capable of being independently switched into service automatically upon failure of the current differential communications.

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