[Claudio]

2700kVA 33000/1050 volt
Dd0 and Dy5 configeration cyclo convertor transformers generating large amounts of hydrogen gas. Various modificationd to the clamp config have been done the Dd0 as proven to be a succes but this hasnt worked on the Dy5.
The core clamps seem to be overheating and burning to the base of the transformer. What other tests/ modifications can be done to conclude this problem??

Topic

[R K Mohapatra]

The copnnection of the transformer viz. Ddo or Dy5 does not have anything to do with the emission of gas . The gas emission is due to the decomposition of Oil or Insulation inside the transformer . The phenomane of gas is primarily due to voltage stress and current stress in the transformer . Considering that the gas comes out even at No-load , there is a voltage stress inside the transformer . Pl check the insulations and the clearnces of dofferent high voltage points to know the source of the gas. This can be attended by improving the insulation . If the gas comes out only at a partaicular load , then it is a current density or Magnetic heating prooblem , which has to be attended differently .

[Hamid]

It is clear, the Dd0 and Dy5 connections are very different in regard to its output current and voltage. Permitted output current of Dy5 connection is 1/1.73 times of Dd0 and it is the technical reason of mentioned overheating.

[Author]

Replies