Buy Dry Type Transformers
Some common misconceptions about Transformers:
Transformers can easily be backfed. Yes and No. Transformers cannot always be reversed willy nilly. Due to cost control some manufacturers design transformers which do not allow the primary and secondary sides to be swapped. Contact your favorite electrical engineering office for your case specifics.
Dry type transformer are designs of convenience and can be stuck in a corner or in any confined space with no problem. False. Dry type transformers are designed for indoor use and are air cooled. They require an adequate supply of moving cooler air to operate within their proper temperature range. If dry type transformers are located in indoor substations, the substations should be properly vented to allow good cooler ambient air flow to circulate in and about the transformer.
PCB (polychlorinated biphenyl), that little man made molecule that was so good it just would not go away, that is, without the help of man. The problem with PCB is also its strength. Unlike many things on the planet, PCB is a highly inert molecule meaning it does not easily combine with other molecules in nature. Drop it off in a field somewhere, come back in 100 years and it will still be there waiting for you in pretty much the same shape you left it. How many things can you say that about? From approximately 1930 through 1979 PCB was used as a dielectric fluid and coolant in old electrical transformers and capacitors. Since 1979 Federal register regulation 40 CFR 761 has regulated the manufacturing, processing, distribution and use of PCB’s in Commerce. Today the use of PCB in existing electrical devices has all but disappeared. Today MIDWEST is actually surprised when we find a PCB transformer.
One popular misconception was that old transformers created PCB as a by product of the electro magnetic process. This myth grew from the fact that many mineral oil filled transformers were found to contain low levels of PCB in their oil. The truth of the matter is not that mystical. The oil in these transformers became cross contaminated with PCB from PCB contaminated pumping equipment used to recondition the oil in these units in the days before PCB was regulated.