Faults detected on live transformer unit



1. Dielectric fluid level is detected as low

The protection relay is empty and the large float is at the bottom.
May be due to:

1.1 Air entering

There must be a dielectric fluid leak and thus oily stains should be visible on the ground. Accurately localize the fault, carry out repair, then recheck the level with the body of fluid at a temperature of 20°C, before switching the unit live again.

1.2 Internal gas emission

Gas should be sampled using a syringe and then analysed.
Whilst awaiting results, under no circumstances should the transformer be switched live again because a risk of total destruction exists.

2. Overheating is detected

This may be due to:
  1. Improper cooling of the transformer (insufficient air flow around unit or plan-troom ventilation),
  2. Continuous overvoltage.

3. Excess pressure is detected

This may be due to:
  1. Overheating
  2. Internal gas emission
  3. Topping up of dielectric fluid with the body of fluid below 20°C; drain the over-flow with the transformer de-energised and the dielectric fluid at 20°C.

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