Transformer Insulation Class Selection

[mbk2k3]

hello folks!

I have a good understanding of transformer insulation classes, the base ambient temp, the temperature rise, hot spots,etc.

However what I'm not finding easily is how to select an insulation class for a transformer?

Is it as simple as: outdoor, hot environment, pick the highest temp. class vs indoor, in electrical room, can get away with lower temp. classes?

 

[Gr8blu]

Have an idea how hard the transformer is going to be working. Are you intending to run "flat out"? If so, you're likely to hit all (or most) of the allowable temperature class. And if that happens - how hot do you think the exterior surface becomes? Is it going to be hot enough to be a burn hazard for nearby personnel (something to think about on shipboard, for example, or in other confined spaces)? Is it in a hazardous (i.e. "classified") location that limits surface temperature so things don't go BOOM?

Operating something up near its insulation class will result in a certain "life" to the insulating materials in the equipment. Operating only 10 C warmer will cut that life in half. Is your transformer starting out with a 40-plus year life? Or only (maybe) 10?

Converting energy to motion for more than half a century