Why do gas-fired transformers appear in electric furnace transformers?
There are three reasons for the frequent occurrence of gas relay action: one is that there is a defect inside the electric furnace transformer; the second is the defect of the transformer accessory or auxiliary system; the third is the gas relay malfunction. The following is a brief introduction:
(1) The internal defects of electric furnace transformers. When the transformer has short-circuit between turns, insulation damage, poor contact, iron core multi-point grounding and other shortcomings, a lot of heat energy will occur, so that the oil decomposes into flammable gas and moves toward the oil pillow (oil storage cabinet) When the flow rate exceeds the setting value of the gas relay, when the baffle of the gas relay is impacted, the circuit breaker is tripped, and then the expansion of the accident is avoided. This situation is generally called heavy gas maintenance action.
When the gas rises along the oil surface and exceeds 30 mL in the gas relay, the signal contact of the gas relay can also be connected to announce the alarm, which is generally called the light gas maintenance action.
(2) Abnormal auxiliary equipment:
1) The respiratory system is not smooth. The breathing system of the electric furnace transformer includes airbag respirator, explosion-proof tube respirator (some products are both in one), etc. The analysis indicates that poor or clogged respiratory system will constitute light and heavy gas maintenance actions, and most of them are accompanied by fuel injection or oil running. For example, a certain 110 kV, 63 MVA main transformer, after being put into operation for six months, light and heavy gas maintenance actions, and pressure valve injection. However, the chromatographic analysis was normal. Upon inspection, the cause of light and heavy gas maintenance actions was the clogged breathing of the transformer bladder.
2) Air leakage from cooling system. When the cooling system is not tightly sealed and the air is entered, or the transformer of the new animal is not degassed by vacuum, it will cause the action of the gas relay.
3) The inlet port of the cooler is closed. Closing the inlet port of the cooler to form a blockage will also cause the gas relay to repeatedly operate.
4) The oil inlet valve on the upper part of the radiator is closed. The closing of the oil inlet valve at the top of the radiator will also cause repeated actions of the gas relay.
5) Transformer intake. The operating experience indicates that the vast majority of light gas maintenance actions are caused by transformers entering the air. There are many reasons for the intake air, mainly including: the aging and damage of the gasket, the deformation of the flange joint surface, the intake air of the oil circulation system, and the intake of sand holes in the welding place.