24 MVA Conservator type Transformer Dessicant Breather is bubbling excessively

[TesterRon]

I am wondering if anyone has seen a conservator silicon dessicant breather excessively bubble. Where I am working there are 3 24 to 33 MVA oil filled transformers in operation. All 3 were found with wet (pink) silicon in the breather. The dessicant and oil were all cleaned and changed with new. 2 transformers are operating normally. However 1 started bubbling continuously and blew out about a couple of spoons full of oil through the dessicant breather, and has been bubbling ever since. This particular transformer lifted the Pressure Relief Device a few months ago. The cause assumed to be a clogged breather. The silicon beads were found pink, wet, and gelatinous at that time. There are no pressure/vacuum gauges, oil level in the conservator is normal, temperatures are normal, and DGA and tank oil sample test results came back with no warnings.

 

[RRaghunath]

PRD operation suggests blockage in the pipe connecting the conservator to tank.
Coming to breather, the silica gel crystal size and shape is important. It should neither be too big or too small/powdery.
If big, the breather will be less effective in removing the moisture in the air going in to the conservator.
If small or powdery, the breather gets packed and will obstruct breathing process (air movement in to and out of conservator). This could be the issue in your case.

 

[bacon4life]

Is the desiccant breather feeding the air side of a rubber bladder in the conservator? Normally air flow through the breather is primarily driven by thermal expansion/contraction due to temperature changes. Do all three transformer have similar load profiles?

If the descant breather is connected to an LTC compartment or a free breathing transformer, excess bubbling might mean gas is being generated within the transformer.

Since the breather was nonfunctional for a period of time, it is possible there a puddle of water inside the rubber bladder. Water turning to steam dramatically increases in volume, though I am not sure about whether evaporating at lower temperatures has the same characteristic.

Are all of the valves in the correct positions? After performing maintenance on a transformer, there are many valves that need to be moved to the opposite state.

 

[prc]

1) Do you have any running oil pumps for the cooler? If so, please check any air sucking in through at any pipe joint on suction side of oil pump.

2) PRD can operate if the breather pipe or silicagel is clogged. But if that is the situation,there will not be any air bubbling out through breather pipe.