Fault Analysis of Oil-immersed Transformer

Common faults of Oil-immersed transformer in operation include winding, bushing, tap changer, core, oil tank and other accessories.

Winding fault

There are inter-turn short circuit, winding grounding, inter-phase short circuit, wire breakage and joint open welding.

Casing failure

Transformer bushing scaling causes pollution flashover in fog or light rain, which causes single-phase grounding or inter-phase short circuit on high voltage side of transformer.

Serious leakage

The oil leakage of transformer is serious or continuous from the damaged part so that the oil level gauge can not see the oil level. At this time, the transformer should be stopped to repair and refuel immediately. The causes of oil leakage of transformer include cracking of welding seam or failure of sealing parts, serious rust and damage of oil tank caused by shock external force in operation.

Tap changer

Common faults include poor contact or inaccurate position of tap changers, surface melting and burning of contacts, discharge of interphase contacts or discharge of taps.

Overvoltage

When the Oil-immersed Transformer in operation is struck by lightning, because of the high potential of lightning, the external overvoltage of the transformer will be caused. When some parameters of the power system change, the Internal Overvoltage of the transformer will be caused by the electromagnetic oscillation. Most of the transformer damage caused by these two kinds of overvoltage is the main insulation breakdown of the winding, resulting in transformer failure.

Iron core

The failure of iron core is mostly caused by the insulation damage of the piercing screw of iron core column or the clamping screw of iron core.

Leakage oil

The oil level of Oil-immersed Transformer oil is too low to expose the bushing lead and tap-changer to air. The insulation level will be greatly reduced, so it is easy to cause breakdown discharge.

More information about our Transformer Corrugated Fins Production Line, please feel free to contact with us : cnkylt@aliyun.com

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