Electrical Question 480V 3 phase

[tmays]

Will the 15 kva 3 phase 480V transformer run the 3 phase 480V 14400-19000 watt piece of equipment? I don’t know the power factor of the piece of equipment. Thanks

B950AD1A-C6C4-46C1-984A-3DC323984DF2.jpeg (23.52 KiB) Viewed 4447 times

CF67522B-D5AC-473B-90BD-379D21891F86.jpeg (21.73 KiB) Viewed 4447 times

[tmays]

Sorry for the pic orientations. I can never tell when it will do that

[SamsFarm]

I would think someone in the maintenance / millrights trades could tell you.

Your pics are too blury to read, especially when zoomed in enough to see.

I expect a few phone calls to the manufactures of the transformer and whatever piece of equipment you are trying to connect is in order.

In my limited experience, I am guessing your answer is no, it will not work.

15kva with a pf of 1 is 15000watts
15kva with a pf of .9 is 13,500watts

I could be wrong, so that is why I recommend some calls to the mfg.

Ps,
That is a lot of power!

[tmays]

15kva with a pf of 1 is 15000watts
15kva with a pf of .9 is 13,500watts

I could be wrong, so that is why I recommend some calls to the mfg.

Ps,
That is a lot of power!

Well I’m the maintenance guy. But I’ve never installed a transformer. Was leaning toward the won’t work, myself. As far as the amount of power, yeah it’s a fancy combi oven that we pulled from a remodel job and just in storage. And have a need for one at a old school that doesn’t have enough voltage available

[Bill V in Md]

I agree the answer is no that particular transformer will not work. The full load amps for a 15 kva 3 ph 480v transformer is 18 amps. I am not sure what kind of equipment that is that you are trying to power, but assuming the power factor is 85% (typical for electric motors), the current draw would be 27 amps, based on a power output of 19kw. Other more resistive loads would have a lower power factor and that would increase the current draw. Even at the lower power output of 14.4 kw, the current draw would be about 20 amps.

[Eugene]

I ran the numbers myself and said it won't work.

Over lunch I had my son, a maintenance electrician, rotate the photos and look over the numbers. He said no.

I think you will need a local electrician to look over the possible installation.

[tmays]

Thanks, fellers. I posed the question because it’s a transformer that’s not being used and an oven not being used. I’ll let the boss know. I’ll check the cost of a new transformer, but one that size won’t be cheap.

[SamsFarm]

I agree the answer is no that particular transformer will not work. The full load amps for a 15 kva 3 ph 480v transformer is 18 amps. I am not sure what kind of equipment that is that you are trying to power, but assuming the power factor is 85% (typical for electric motors), the current draw would be 27 amps, based on a power output of 19kw. Other more resistive loads would have a lower power factor and that would increase the current draw. Even at the lower power output of 14.4 kw, the current draw would be about 20 amps.

Wondering how you came up with your amp ratings.

I am no electrical guru, but thought Ohm's law was Volts x Amps = Watts

14,400w / 480v would equal 30 amps, unless I am missing something.

Maybe something with the 3 phase that changes the amp draw. ??? Please explain!

[Bill V in Md]

I agree the answer is no that particular transformer will not work. The full load amps for a 15 kva 3 ph 480v transformer is 18 amps. I am not sure what kind of equipment that is that you are trying to power, but assuming the power factor is 85% (typical for electric motors), the current draw would be 27 amps, based on a power output of 19kw. Other more resistive loads would have a lower power factor and that would increase the current draw. Even at the lower power output of 14.4 kw, the current draw would be about 20 amps.

Wondering how you came up with your amp ratings.

I am no electrical guru, but thought Ohm's law was Volts x Amps = Watts

14,400w / 480v would equal 30 amps, unless I am missing something.

Maybe something with the 3 phase that changes the amp draw. ??? Please explain!

I actually consulted published data for the capacity of a 15 kva transformer and found that it was 18 amps.

But to your point, power in any balanced polyphase system equals line voltage times line current times the power factor times the square root of the number of phases: Assuming a PF = .85 and solving for current;
I = 14.400 / (480 x .85 x 1.73) or 20.4 Amps

[SamsFarm]

Thank you Bill V