Using transformer differential relay I{sub op} characteristics to measure near-trip conditions

Conference · Sun Dec 31 04:00:00 EST 1995

OSTI ID:277504

Criss, J; Lawhead, L ^[1]

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1. Basler Electric Co., Highland, IL (United States)

When a transformer differential relay operates with no obvious transformer fault, system operators have a serious decision to make: is there a transformer fault, or did the relay trip incorrectly? Testing the transformer requires significant time, with associated costs. However, re-energizing a faulted transformer can lead to catastrophic failure. This scenario of a questionable transformer trip occurs too often, especially during the commissioning of new transformers and/or differential relays. Usually a differential relay false trip is caused by either incorrect settings or incorrect current transformer (CT) secondary lead connections. These conditions can cause false trips for external faults, or simply transformer loading. Some indication is needed that the relay is not operating as desired, before an incorrect trip happens. A potential problem can be discovered by monitoring the operating condition of the differential relay. An indicator can serve as a warning if the settings or connections are not correct.

• OSTI ID: 277504
• Report Number(s): CONF-960509--; ISBN 0-7803-3263-6
• Country of Publication: United States
• Language: English

Related Subjects

20 FOSSIL-FUELED POWER PLANTS
EQUIPMENT PROTECTION DEVICES
PERFORMANCE
POWER SYSTEMS
RELAYS
TRANSFORMERS