Transformer Protection

Oil Surge Relay (OSR) – Construction, Working, and Function

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An Oil Surge Relay, or OSR, is a type of mechanical relay. It operates in response to a sudden oil surge. Need for Separate Diverter Tank Every modern power transformer includes an On-Load Tap Changer (OLTC). During tap-changing operations, some arcing always occurs at the diverter switch contacts. It is desirable to change tap positions … Read more

Buchholz Relay — Construction and Working

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The Buchholz Relay is a gas-actuated protection relay. It is a mechanical relay. All oil-immersed transformers that have a conservator tank should be equipped with a Buchholz relay. A Buchholz relay can detect both slow-developing faults and major transient faults occurring within the transformer. It provides an early warning (alarm) for slow-developing faults and initiates … Read more