Power Transformer 55/65 Degree C Rating
Power Transformer 55/65 Degree C Rating
(OP)
Please explain what the meaning of insulation temperature rating of a power transformer.
I am confused as to what a 55 Degree C, a 55/65 Degree C, and a 65 Degree C designation really means.
Also, it is my understanding that the lower the temperature rise the lower the rated full load capacity of a power transformer. Why?
Thank You.
I am confused as to what a 55 Degree C, a 55/65 Degree C, and a 65 Degree C designation really means.
Also, it is my understanding that the lower the temperature rise the lower the rated full load capacity of a power transformer. Why?
Thank You.






RE: Power Transformer 55/65 Degree C Rating
If a transformer has a 55°C rating, this is the loading that will produce a 55°C hot spot temperature. This is less than the loading that will produce a 65°C hot spot temperature because higher loading produces higher temperatures. Some users want to know how much more they could load the transformers if they took advantage of the newer insulation technology, so require both a 55°C and a 65°C rating.
RE: Power Transformer 55/65 Degree C Rating
If a transformer is rated with a 55/65 Degree C designation, what is the actual insulation rating? Is it 55 or 65 Degrees C?
What is the actual KVA of the transformer? Is it the 55 Degree C KVA rating or the 65 degree C KVA rating?
Thanks,
KingJoey
RE: Power Transformer 55/65 Degree C Rating
One rating is as real as the other. Generally, I'd use the 65 deg C rating in describing the transformer capacity.
RE: Power Transformer 55/65 Degree C Rating