TRANSFORMER SIZE
TRANSFORMER SIZE
(OP)
I have following information on 120/240V loads
MOTOR STARTING + CONTINUOUS LOADS
Single phase – 120 kVA
Three phase – 51 kVA
MOTOR RUNNING + CONTINUOUS LOADS
Single phase – 104 kVA
Three phase – 12 kVA
AFTER 10 SEC (CONTINUOUS LOADS ONLY) KVA
Single phase – 97 kVA
Three phase – 6 kVA
I would like to size a transformer, which could handle this load. Assuming a unity power factor, which transformer size do you think is appropriate?
I am leaning towards a 300 kVA delta secondary padmount transformer.
Could possibly use a 225 kVA. Any suggestions? ( Primary is a 24kVY)
MOTOR STARTING + CONTINUOUS LOADS
Single phase – 120 kVA
Three phase – 51 kVA
MOTOR RUNNING + CONTINUOUS LOADS
Single phase – 104 kVA
Three phase – 12 kVA
AFTER 10 SEC (CONTINUOUS LOADS ONLY) KVA
Single phase – 97 kVA
Three phase – 6 kVA
I would like to size a transformer, which could handle this load. Assuming a unity power factor, which transformer size do you think is appropriate?
I am leaning towards a 300 kVA delta secondary padmount transformer.
Could possibly use a 225 kVA. Any suggestions? ( Primary is a 24kVY)






RE: TRANSFORMER SIZE
RE: TRANSFORMER SIZE
Bill
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"Why not the best?"
Jimmy Carter
RE: TRANSFORMER SIZE
That was my understanding that the mid tapped winding will carry 2/3 of the single phase load (2/3*120 =80kVA) and 1/3rd of the three phase (1/3*51 = 17kVA).
The other two windinging will take 1/3rd of both single (1/3*120 = 40kVA) and three phase loading (17kVA). However, now I am a little confused from Davidbeach's comment that a 300kVA will only serve a 50 or 60 kVA single phase load. David, where did you come up with this number?
I have not worked with padmount transformers before, but think that it would on the same principle as a bank of three single phase equal impedance transformers. Is that not correct?
RE: TRANSFORMER SIZE