transformer life expectancy 3

[sarsca]

Hello,
I don't have the make and model # yet, but I have been asked to give an opinion on the life expectancy of a 17 year old 225 kva transformer. The existing load is about to be increased beyond its' capacity and we need to determine if it is better to upgrade with one larger Tx. or to add a second smaller one. The new loads can be split up to accomodate this. The Tx has been inside a building for its' entire life. It is a delta to wye, 600 to 460volt unit that seems to have been supplying a 25kva load. Is there a formula or calculation or rule of thumb to be applied here?

 

[dpc]

Dry type?

It's really hard to predict for these little guys. If it hasn't seen too many through-faults, it should last 30 years, but of course, will probably fail as soon as you buy the second smaller transformer.

Temperature is the strongest predictor. If it has been lightly loaded and kept reasonably clean, it should have a lot of life left.

 

[jghrist]

Will it be moved? Moving the transformer may affect insulation that is brittle from age and heat, causing a failure that would not occur if the tranformer is not moved.

 

[Zogzog]

The best way to know is to have it tested, however after the cost of testing + the cost of adding another small unit you could have bought that larger one.

 

[wbd]

have you considered what replacing the existing one with a larger transformer would do to the arc flash hazard? It most likly will increase. You may be better off splittign the load.