Transformer Overheating
Transformer Overheating
(OP)
I have two 10MVA ONAN rated transformers operating in parallel. These serve as standby supply for a Soda Ash mine, who has own generation plant of 15 MVA.
When the mine generation is out, the total load is about 8MW on each transformer.
At this load one transformer's winding gauge shoots to 105 degrees Celcius whilst the other remains 85 degrees Celcius.
The oil gauges of the two transformers are comparable, reading close to 65 degrees Celcius.
What could be the cause?
When the mine generation is out, the total load is about 8MW on each transformer.
At this load one transformer's winding gauge shoots to 105 degrees Celcius whilst the other remains 85 degrees Celcius.
The oil gauges of the two transformers are comparable, reading close to 65 degrees Celcius.
What could be the cause?






RE: Transformer Overheating
RE: Transformer Overheating
Gauge fault ? Try interchanging the gauges and see if the high temp goes with the gauge or stays with the trafo.
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RE: Transformer Overheating
The next thought was: the winding temperature instruments are calibrated to match the characteristics of the transformer. The high reading on one of them could be simply that it is not reading correctly.
RE: Transformer Overheating
RE: Transformer Overheating
If the impedance of one transformer is less than the other, that transformer will take a greater share of the load.
respectfully
RE: Transformer Overheating
RE: Transformer Overheating
First step is to check the current on CT secondary to see if you have a current difference at that point.
If different: next step is to check CT taps for equivalency. Then investigate for actual primary current difference.
If same, investigate temperature indicator and heater circuit.
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RE: Transformer Overheating
Iam with electricpete,check for any loose connection on the CT circuit.