Calculating KVA for 208/230V 3 phase

[tejeshbagul]

Hello,

I am trying to calculate the KVA for a 208/230Volt, 27.7Amps electrical heater and split it into 2 circuits in a 3Phase panel.

Is the following the right way?

VA=Voltage x Amps x √3 = 230 x 27.7 x [FONT=arial, sans-serif]√3 = 11034.89 (if yes why can't I use 208 instead of 230)[/FONT]

[FONT=arial, sans-serif]KVA=11.034[/FONT]

[FONT=arial, sans-serif]for splinting it into 2 circuits = 11.034/2 = 5.5KVA

Any help is highly appreciated.

Thanks,
Tejesh

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[ron]

Is it single phase or three phase?

The 27.7A is the value at 208V or 230V, you will need to figure that out.

Why do you want to split it into 2 circuits, that will be a weird connection if it is possible at all.

Maybe post a picture of the nameplate.

 

[Dennis Alwon]

Is it single phase or three phase?

The 27.7A is the value at 208V or 230V, you will need to figure that out.

Why do you want to split it into 2 circuits, that will be a weird connection if it is possible at all.

Maybe post a picture of the nameplate.

Many large heaters are fed with three phase and then subdivided. We can't have more than a 60 amp overcurrent protective device on the heaters so it has to be subdivided. Thus a 15kw furnace is usually split into a 60 and 30 amp ocpd. 424.22(B)

 

[GoldDigger]

Is it single phase or three phase?

The 27.7A is the value at 208V or 230V, you will need to figure that out.

Why do you want to split it into 2 circuits, that will be a weird connection if it is possible at all.

Maybe post a picture of the nameplate.

I think what the OP means is that it will be connected line to line (although it should be on one two or three pole breaker). And how do you handle the VA when filling out the panel schedule?

 

[Smart $]

... And how do you handle the VA when filling out the panel schedule?

Assuming single phase, one half the VA goes in each of the two columns the heater is connected to.

 

[GoldDigger]

And if the unit draws the same amperage at 208 as it does at 230 (unlikely) the wattage will be 27.7 x 208. The sqrt(3) does not come into play. Although if absolutely no other loads exist the real VA on each lead will be 27.7 x 120. But the NEC calculation does not seem to address that.

 

[Ingenieur]

What is the panel voltage?
is the heater 1 or 3 phase?
you want to seperate it into 2 loads, 50/50 or 1/3 2/3?
will the seperated loads be 1 or 3 phase
is the 27.7 at 208 or 230?