SERGI - On Load Tap Changer

TRANSFORMER PROTECTOR


	On Load Tap Changer (OLTC) [12]


	In addition to the tank, SERGI strongly recommends to protect the On Load Tap Changers and the Oil Bushing Cable Boxes with the TRANSFORMER PROTECTOR. For that purpose, a Depressurisation Set and a specific Explosive Gas Elimination Set are used.


	Protecting all transformer oil capacities prevents the short-circuit from damaging the On Load Tap Changer or the Oil Bushing Cable Box, and spreading the fire to the transformer itself as well as to the whole power plant or substation. The TRANSFORMER PROTECTOR therefore offers complete protection of the transformer for a minor additional price

Examples exist where as little as 200 litres (53 gallons) of burning oil from the OLTC have destroyed a complete substation.

When not connected to the TRANSFORMER PROTECTOR, OLTCs are protected against overpressure with a diaphragm or a Pressure Relief Valve, which are not calibrated and do not allow oil channelling during an explosion. In fact, during short-circuits, the OLTC cover is always forced off and burning oil then spreads onto the transformer, floor and surrounding equipment, leading to a fire expansion to the whole plant

Hence, short-circuit consequences are more severe when transformers are located underground, inside industrial plants with high explosion risks or in sensitive environmental areas. They must therefore absolutely be protected.

SERGI’s long collaboration with major OLTC manufacturers has resulted in the protection of every type of OLTC. This is why SERGI strongly recommends to protect all of them, using a flange for depressurisation and a pipe that goes to the bottom of the OLTC to eliminate explosive gases.