Dry Type versus Oil Filled Transformer
Dry Type versus Oil Filled Transformer
(OP)
We are working on selecting a new transformers and main switchboard for an industial facility. We plan on using two 2500 kVA transformers (13,200 to 480 volts) and a main-tie-main main switchboard.
We can locate the transformers either indoors or outdoors.
What are the advantages and disadvantages of the dry type (e.g. Square-D Powercast) and oil filled transformers?
Thanks!
Michael
We can locate the transformers either indoors or outdoors.
What are the advantages and disadvantages of the dry type (e.g. Square-D Powercast) and oil filled transformers?
Thanks!
Michael






RE: Dry Type versus Oil Filled Transformer
RE: Dry Type versus Oil Filled Transformer
2. Initial cost for oil filled is lower than power cast.
3. Oil filled are more flexible for outdoors usage.
4. Oil filled handles moderates overloads and has higer BIL than dry type.
I suggest you to read Square D bulletin No. 7300pd9203.
Joseph Cortes.
RE: Dry Type versus Oil Filled Transformer
Cast coil transformers can be placed outdoors and actually have a higher fan cooled rating boost than oil-filled.
But they are more expensive.
Biggest disadvantage to oil-filled transformers is fire hazard and the oil itself. High-fire-point oils are available, including vegetable oil, but these cost more than standard mineral oil.
Dry-type allows you to close couple transformer to secondary switchgear - with outdoor units, you must run bus or cable.
RE: Dry Type versus Oil Filled Transformer
There are few dielectric fluids options that could help to mitigate some of the negative aspect associated with conventional dielectric oil in transformers. Today there are available biodegradable fluids with flash point ~330 oC & fire point ~360 oC. Other fluids have an acceptable fire retardant characteristic and not contaminant such as Dow Corning 561 Silicon Fluid with flash point ~300 oC & fire point ~330 oC.
There are several technologies available to perform online diagnostic of the oil with acceptable level of accuracy that could help reduce the O&M cost.
Sample of those products are.
http://search.abb.com/library/ABBLibrary.asp?DocumentID=1LUS471050-LTE&LanguageCode=en&DocumentPartIdD=&Action=Launch
http://www.cooperpower.com/library/pdf/92009.pdf
http://www.faradayhouse.co.uk/ConditionMonitoring.htm
RE: Dry Type versus Oil Filled Transformer
Michael
RE: Dry Type versus Oil Filled Transformer
Also, we used a silicon oil in some applications to minmize fire hazards.
Good luck.
RE: Dry Type versus Oil Filled Transformer
RE: Dry Type versus Oil Filled Transformer
Outdoor installation I would go with oil.
RE: Dry Type versus Oil Filled Transformer
Oil seems to be more robust and over say last 10 years plus has in my experience shown less failures.
Dry type transformers can be noisy ( audible and electrical). Audible noise emissions seems to be from the tin work. Electrical arises from local arcing on the covers. Not good if you have sensitive equipment nearby.