Addition of 3PH and 1PH loads

[7JLAman4]

If I have (1)36kVA 3PH load, (1)10kVA 1PH-A, (1)15kVA 1PH-B and (1)15kVA 1PH-C loads, is my total effective kVA load 36+15+15+10= 76kVA for sizing a generator to supply them (assuming they are operating simultaneously).

 

[ScottyUK]

A generator is rated assuming a balanced three phase load. You should look at the maximum current on each phase, and size the generator based on that current, otherwise you will overload the winding of the generator. You will end up with two phases underutilised and one somewhere near its rating. Allow some margin above the calculated load - it is not good practice to size a generator exactly to match the load.

Heavily unbalanced loads are not desirable because of the negative phase sequence heating of the rotor. On small sets this rarely seems to be a practical problem and can probably be disregarded.


----------------------------------

I don't suffer from insanity. I enjoy it...

 

[Senselessticker]

Effective kVA = 36/3 + 10 + 10 + 15 = 47 kVA, with phase C taking 27 kVA. Applying what ScottyUK stated, 27 x 3 = 81kVA. Of course there are many other factors when it comes to actually sizing the generator.