Transformer evaluation

[BEPC13]

I am in the process of puchasing a transformer for a project I am doing. One of our first steps in evaluating the bids is looking at the mass of the units. We found them to be about the same with a caveat. One manufacturer had much more core and coil weight and less oil than the others. Around 20 K lbs. My question is this, is this transformer much better than the other units with less steel and copper and more oil? My thinking is the metal is more expensive that mineral oil. However I can not come up with a dollar value to place on the extra metal to do bid evaluations.

 

[jghrist]

Manufacturers make different design choices. More core and coil usually means lower losses, less heating, and less need for cooling. There is no way I know of to evaluate the design based on mass. The best way is to directly evaluate the losses by determining how much (in discounted present value) the losses will cost you over the life of the transformer. The loss evaluation factors should be specified in the bidding documents so that manufacturers can design the units most efficiently for your needs.

 

[hmchi]

Most manufacturers will provide very reliable loss data when purchaser invoke a penalty for delvieries that failed to meet the stated losses criteria. This is usually the most important evaluation issue.

The type of insulation material used is another important cost factor affecting the lifespan of the transformer.