Ambient temperature and transformer performance
Ambient temperature and transformer performance
(OP)
Smaller oil field transformers (300 MVA) 34.5/480 V may occasinally be exposed to a minimum ambient temperature of –40 DEG C, while the manufacturer stated that the transformer operating temperature range is -30 C _ 50 C. Could someone comment what are major consequences if an oil transformer is exposed to temperatures below the range they are designed for?






RE: Ambient temperature and transformer performance
If it had been sitting de-energized at that temp, I would be concerned that the oil would be too thick for thermosiphon effect to keep oil moving.
RE: Ambient temperature and transformer performance
How do they deal with this (transformer design for very low winter temperature conditions)- is this just the matter of using different type of oil or there are other considerations related the transformer geometry and similar?
RE: Ambient temperature and transformer performance
Mineral oil thickening is one thing, but other coolants, like R-Temp, would definitely have flow problems.
I believe you may find that even when the transformer is running, an ambient temp of -40° C would cause problems if the manufacturer lists -30° C as the limit.
RE: Ambient temperature and transformer performance
I believe for cold ambients it was something like an increas of 1.8% per degree below freezing ( 32 Degrees ) and 0.8% decrease. for temps over 104 degrees.
I think those figures are in the GE distribution transformer booklet. That booklet is somewhere on the web.
I don't have any of the books here, I can take a look this weekend.
I recall the parking lot transformer ( for vehicle heaters ) in NoDak could be loaded about 250% on the colder days.
RE: Ambient temperature and transformer performance
Does anyone know if such condition (when the oil starts to solidify at very low temperatures) has a negative impact on the oil dielectric strength?
RE: Ambient temperature and transformer performance
I recall reading a paper where the startup procedure for a cold-environment substation included circulating the xmfr oil through a heater to bring it up to a min temp, but I think this was for the DEW line in Northern Canada. I'll see if I can find it again.
RE: Ambient temperature and transformer performance
RE: Ambient temperature and transformer performance
http://cuky2000.250free.com/Tr_Load.jpg
One possible option is to use supplementary heater and/or using cooling fluid with lower frozen temperature.
Beware that sub-zero temperature is not a usual condition and has to be addressed with the transformer manufacturer.
Paraphrasing Yogi Berra, engineering is 90% technical and the other half is administrative.
RE: Ambient temperature and transformer performance
RE: Ambient temperature and transformer performance
Mike
RE: Ambient temperature and transformer performance
I’m just trying to digest some related info reading IEEE transformer book (C57), which has about 2000 pages, and still it does not seem to say much if anything about very low ambient temperature conditions...
In terms of rating, ANSI seem to suggests that at low ambient temperatures the transformer could be uprated for 1% for each DEG Celsius below +30 C but above 0 C, however it doesn't seem to elaborate what happens below 0 C ("consult with the manufacturer", they say).
RE: Ambient temperature and transformer performance