Gas formation in Transformers

Gas formation in Transformer oil is an indicator of problems inside the transformer.  Gas can be formed due to the decomposition of either the oil or the insulation of the windings.

The gas formation in transformers can be gradual or sudden.  Gradual  Oil decomposition can be caused due to minor leakage faults within the transformer, internal short circuits.  Loose connection of the windings can also be a reason for gas formation.   Overheating of insulation is another cause for the formation of gas.

The Gas thus formed tends to get dissolved in the transformer oil.  The dissolved gas can be detected by Dissolved Gas Analysis.  The dissolved gas can get released when the transformer experiences temperature fluctuations during its operation cycle.

Major faults such as flashovers lead to sudden gas formation in Transformers.

The Bucholz relay is the protection in transformer against gas formation.  Minor gas formation will accumulate inside the relay and activate the top most float.  This can be configured for alarm  Sudden discharge of gases due to major faults will cause the bottom float in the relay to operate and trip the transformer.

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