Sudden Pressure in Power Transformers

[Uquresh1]

Can someone describe how, or what is 'Sudden Pressure' in the Power Transformers. I have used this Sudden-Pressure signal from the transformer to trip the transformer immediately, but still don't know what it exactly is, or how/why it occurs.
Thanks.

 

[lavurk]

There is abnormality in the power Transformer.There may be following reasons
1) Dielectric strength of oil is low
2) High Temperature of oil
3) Short circuit in the windings
4)Malfunctioning of Buck Holz relay etc..

Isolate power supply to Transformer and verify the above.

 

[ScottyUK]

Sudden pressure within a transformer is almost always associated with evolution of gas. If gas is evolving at a rapid rate then it is usually indicative of an aggressive fault, probably arcing within the tank causing dissociation of the oil.

A sudden pressure relay is normally used on a hermetic transformer and is analogous to the oil-surge trip signal from a Buchholz relay on a conservator type transformer. A sudden pressure relay can be a useful device to initiate a trip before the fault becomes severe enough to activate the pressure relief device thus limiting the extent of damage, although the PRD auxiliary switch should always be in the tripping scheme too.


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If we learn from our mistakes I'm getting a great education!

 

[oldfieldguy]

The sudden pressure relay reacts to rapid pressure rise due to a fault in the transformer tank. It is also known by "rapid pressure rise" and "Fault pressure" relay.

The theory is that an arc event in the transformer tank will cause a rapid change in pressure. Since the relay is set up to react only to rapid pressure changes, pressure changes due to temperature or leaks or replenishment of inert gas are typically ignored by the relay.

These are typically set up to operate the protective circuit to trip and isolate the transformer in the same manner as a transformer differential event, i.e., a serious fault that requires investigation and testing before re-energizing the transformer.

old field guy

 

[cranky108]

Sudden pressure relays can also react to gelogical vibrations, so in some parts thay use another means to guard for that condition.