Transformer Loading
Transformer Loading
(OP)
I have some concerns about adding load onto a 1500 KVA transformer and wanted to find out what the accepted method of determing the allowable load to the transformer. It appears from the drawings I have of this and several other 1500 KVA transformers that the total H.P. + KVA attached to them exceeds 1500 KVA.
Is it okay to use actual current readings to determine tha actual load on the transformer. It seems that all the motors and other devices fed from the transformer would not be pulling full load amps all the time.
Thanks for any help!
Doug
Is it okay to use actual current readings to determine tha actual load on the transformer. It seems that all the motors and other devices fed from the transformer would not be pulling full load amps all the time.
Thanks for any help!
Doug





RE: Transformer Loading
To size the transformer then we have:
Lighting load – 200 kW ( no diversity - it’s on 24 hours/day)
Heating load - 250 kW ( only 50% of total at anytime normally)
Total transformer load = 200 + 250 = 450 kW. Assume a power factor of 90 % and we end up with a total load of about 450 kW/0.90 = 500 kVA.
The transformer should be a 500 kVA unit. The overload ability of the transformer for a short duration would allow you supply a greater load assuming a return to normal loading say within a day or so.
Hope this helps.
RE: Transformer Loading
Max. load per phase is 500 kVA
Let's say phase to neutral voltage is Vfn. (phase to phase voltage divided by the square root of 3)
Then, actual line current (amperes)must not exceed quotient between load (VA) and Vfn (volts) appart from overload conditions explained by Newton1Law,
Julian