full load for transformer

[mwuniseal]

Greetings,
I have a 1000/1333 kva fan cooled transformer 8 % impedance. Primary voltage is 4160, secondary is 480/277. My question is this: The transformer should deliver approximately 1600 amps at full load if the fans are operational ( which I am not sure if they are). If the fans are not operational does that limit my transformer to the 1000 kva stamp? This would give me approximately 1200 amps. My next question concerns a power factor that averages 90%. Does this also derate my kva?
Thank you for your help

 

[iceworm]

... a 1000/1333 kva fan cooled transformer 8 % impedance. Primary voltage is 4160, secondary is 480/277. My question is this: The transformer should deliver approximately 1600 amps at full load if the fans are operational ...

Yes

... If the fans are not operational does that limit my transformer to the 1000 kva stamp? This would give me approximately 1200 amps. ...

Yes

... My next question concerns a power factor that averages 90%. Does this also derate my kva?...

No

ice

 

[jcormack]

The kVA rating of the transformer is essentially as "heat rating" - how much power can it pump out without having insulation failure - that is why you can have a higher kVA with fans, the fans cool it & allow it to pump out more amps. If you cool it with cold air you could pump out even more. So yes, if the fans are not functional and you load it in excess of 1000 kva (for a long period of time), it will eventually fail - short term OLs may not cause a problem, it really comes down to the thermal withstand curves of the coils. If you have 1200 amps @ .9 pf the transformer will be able to produce 900kW of real power - if you have 1200 amps @ .8 pf you will be able to have 800 kW of real power loads if you have a pf of 1 then you can produce a full 1000 kW so yes pf plays a part in how you can load a transformer that is why they give the ratings in kVA. I would like to point out that really low pf will also result in more transformer heating and lower efficiency and a worse voltage regulation - most large transformers will have transformer losses -vs- pf curves, as well as thermal with-stand curves.

 

[Besoeker]

Greetings,
I have a 1000/1333 kva fan cooled transformer 8 % impedance. Primary voltage is 4160, secondary is 480/277. My question is this: The transformer should deliver approximately 1600 amps at full load if the fans are operational ( which I am not sure if they are). If the fans are not operational does that limit my transformer to the 1000 kva stamp? This would give me approximately 1200 amps. My next question concerns a power factor that averages 90%. Does this also derate my kva?
Thank you for your help

Should not do so. The rating is really current.