typical life span oil cooled transformer?
does anyone know what is typical life span oil cooled transformer? 20 - 30 years before it won't be efficiency?
20-30 years is not all that unusual especially if it had provisions to sample and service the oil and it was loaded with an ambient temperature as would normally anticipate achieving that life. Remember that there are all sorts of variables that have an effect on transformer life.
But, efficiency? I see no reason for the efficiency to change.
It is primarily heat that kills transformers, not age in years.
Provided that the transformer is in a well ventilated area, not overloaded, or otherwise abused, then I would expect a life of AT LEAST 30 years.
The load on POCO transformers is very variable, and they often survive longer in cold climates.
In a cold climate, the peak oload is likely to be on the coldest day of the year due to electric heating, the cold ambient partly compensates for the high loading.
In a hot climate, the maximum load is likely to be on the hottest day of the year due to widespread use of air conditioning. Unless the transformer is generously sized, this can contribute to a shorter life.
As the years go by, there is a slightly increased risk of failure.
I would not expect the efficiency to decline with age.
Working for a POCO, we are actively involved in reconductoring a system started 75 years ago. We often take down transformers installed 40-50 years ago with no sign of deteriorated performance. Usually the coils and oil will last decades as long as the transformer has not been over heated repeatedly. The "paper" insulation is what we have typically seen as the culprit when we do experience a failure from within...
40 years with oil conditioning, if needed. I had single phase 750kVA GE transformers(6) in service over 80 years and they were still ticking along fine, even though they were free breathing with only a bug-screen over the went pipe that was a piece of two elbows with the open end facing the ground. Oil tested fine. the loading was about a constant 75% in the upstate NY (Albany) area.
Originally Posted by anbm