KW losses in a transformer bank

[COMAPRO]

a customer of mine has a trnasformer bank , 3 x 100 KVA , which 300 KVA totally, the Demand is only 120 KW and has capacitors to keep above 0,92 the power factor of the plant. the question is is there any KW losses at all because the transformer bank is over designed for the plant operation ? if so , how much would that be ?

I would appreciate very much if you can give me your profesional opinion on the subject asap because I am middle of a report for the referred customer.thank you.

 

[dpc]

Transformer losses are composed of core (iron) losses and winding (copper) losses. The core losses are constant and are a function of the transformer rating. Winding losses vary with the square of the transformer load.

So, if you had a smaller transformer, core losses would be reduced. However....these losses are quite small, well below 1% so if you have a 150 kVA transformer your core losses would be reduced by half of this very small number.

Also, there may be other reasons for the larger transformer, such as allowing for motor starting, etc.

I think the payback on buying a smaller transformer to reduce core losses would exceed your customer's remaining lifespan.

If this transformer is the main service to a facility, it is likely owned by the utility and metered on the low side. In this case, the losses are actually not metered, so there would be no financial savings at all. This would make the payback quite a bit longer.