Deenergized Transformers in Winter
Deenergized Transformers in Winter
(OP)
I am looking for anyone's personal experience with shutting down their transformers for the winter. We have some peaking power plants with multiple Generator Step-Up transformers and would like to shut down all but one GSU for the off-season (winter). Our GSUs have conservator tanks and are located in central US, where minimum temp may reach -30C. I read the manufacturer's literature and they warn against letting the oil level go too low due to low temperature due to the possibility of air entering the main tank. I really don't want to keep a transformer humming all winter drawing 120kW in no-load losses, costing over $3000 per month in demand and energy charges.
Has anyone come up with a solution to this issue? I've considered rotating transformers regularly but haven't figured out a way to determine the actual oil temperature or how long it will take for a transformer to cool down after being energized and warmed up. Any input would be appreciated.
Has anyone come up with a solution to this issue? I've considered rotating transformers regularly but haven't figured out a way to determine the actual oil temperature or how long it will take for a transformer to cool down after being energized and warmed up. Any input would be appreciated.






RE: Deenergized Transformers in Winter
Is there a way you can cover and heat them? I have built shelters for things ( not transformers ) using insulated kelly closures.
http://www.kellyklosure.com/index.html
There are also insulated "blankets" that you could use for wrapping them up. Look for the "blankets" use to keep concrete from freezing when it is place in cold weather.
You clould try that along with a space heater.
How big are your transformers?
You can heat them internally using a welder connected to the secondary windings. You will put less power in it than by energizing it with no load.
If I were doing this I would put an alarm system on it. Heating the transformer up and cooling is not good.
RE: Deenergized Transformers in Winter
I have on some projects in the past used a low voltage, such as 120 or 480 to energize the transformer windings to keep just a small amount of heat in the tank. I only remember doing this for spare transformers that would be in storage on a pad for indefinite periods of time. It would be somewhat of a safety problem and operational headache to do it on a unit that is being used occasionally.
I think I would discuss it with the transformer supplier and see what their recommendations are. There are hundreds of these units out there now with the same problem.
I agree with BJC that cycling the transformers during the cold months would probably be worse than just leaving them off.
RE: Deenergized Transformers in Winter
I have seen substation transformers de-energized during the winter that used a nitrogen blanket and not a conservator tank like yours.
If you were intent on de-energizing them, I'd let them cool off while monitoring the oil level in the tank, watching it so it doesn't get too low and cause you problems. You may have to add oil in the fall, and drain it off in the spring as they warm up.
Mark in Utah
RE: Deenergized Transformers in Winter
May be this helps.
elect
RE: Deenergized Transformers in Winter
RE: Deenergized Transformers in Winter