Single Phase to three phase power conversion

4 replies [Last post]
hainats's picture
Joined: 2014-04-01

Please, can anyone clarify how to arrive at the total power consumption from the below details?
400V, 3ph+N, total load is 17.92kW
230V, 1ph+N, total load is 16.06kW

USS Hornet's picture
Joined: 2015-01-07


The answer is 33.98kW. You simply add the loads' kW. Buildings have three-phase and single-phase loads. The service doesn't care. All it cares about is the kWs.


JPaul's picture
Joined: 2015-05-13

Gentlemen, please help.
Our power system is 3-phase, four wire 400/230V (we're using diesel generator as power source). If I have single-phase loads (L-N) of 10kVA in line A to neutral, 12kVA in line B to neutral, and 10kVA in line C to neutral and a three-phase load of 5kVA, how can I compute the total current so I know what size main circuit breaker I need?

Joseph Temowo's picture
Joined: 2015-01-07

You need a 350A Main Breaker. The loads are as follows: Ian = 43.5A, Ibn = 52.2A, Icn = 43.5A and I-3phase = 144.34A.

Breaker Size = 144.34A X 1.25 + 43.5A + 52.2A + 43.5A = 320A

Bisnes's picture
Joined: 2015-05-17

We think that the size of Main Breaker is 150 Amps, because the 3-phase load is 8.02 Amps instead 144,34 Amps.

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