ARIKSON ESPINAL
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We all know that overcurrent relaying is commonly used for fault protection of transformers having CB's only when there is no justification for the cost of differential relaying.
Overcurrent relaying has not the sensitivity of differential relaying.
Three CT?s, (one p/phase), and at least two overcurrent phase relays and one overcurrent ground relay should be provided on each side of the transformer bank that is connected through a circuit breaker to a source of short-circuit current.
Question is: What's necessary for obtaining good protection for external faults in the option that the transformer bank is connected to more than one source of short-circuit current?
thanks in advance.
Overcurrent relaying has not the sensitivity of differential relaying.
Three CT?s, (one p/phase), and at least two overcurrent phase relays and one overcurrent ground relay should be provided on each side of the transformer bank that is connected through a circuit breaker to a source of short-circuit current.
Question is: What's necessary for obtaining good protection for external faults in the option that the transformer bank is connected to more than one source of short-circuit current?
thanks in advance.