One thing to think about with the drytype is it's rated temperature rise. There are typically three ratings: 80Â°C, 115Â° and 150Â°C. The higher the ratingâ€”the hotter it runs under load, with some electrical energy turned into heat.
I wouldn't hesitate to contact the transformer manufacturerâ€™s' rep and ask them to weigh the advantages and costs of the three ratings. An initially higher-cost, lower temperature rise transformer may be cost effective over its expected life in less heat generated in the transformer room, and potential energy savings. Plan on clearances around the transformer to be no less that specified on the transformer label. Higher-rise units may require increased clearancesâ€”remember these instructions are part of the deviceâ€™s NRTL listing. [It is surprising the amount of heat a ventilated dry-type transformer can produce.] If in a yearâ€™s time more electricity is used for air conditioning than heating, the lower rise unit can have an additional advantage. Aside from temperature rise is the rating of the transformer insulation system. 220Â°C-rated insulation is desirable and fairly standard.
Most transformer termination kits come in two stylesâ€”compression and setscrew type. With normal vibration and heat cycling, the compression type are better if you have or can borrow the right tooling.
Several above- and below-normal 2Â½% voltage taps are typically furnished with a 50kVA unit.
Ask too about the noise from the drytype in the intended location with respect to the building occupants. Unlike temperature rise, noise levels do not change significantly with load.