I have some basic three phase question, if someone could help with please.
I have left power factor a 1 for simplicity.
If I have a 63A three phase and neutral BS 60390 socket - I presume that means it can carry 63A per phase so 189A.?
But because of the displacement of the windings, you would never draw 186A at the same time as some phases will be in the negative cycle.
But theoretically it can handle 189A?
If I had load of 10kW on a single phase supply that would be 10,000/230 = 43.5A. So a 45 / 50 A MCB would be needed
If I had a load of 10kW on a 3 phase supply that would be 10,000 /( 1.73 x 400) = 14.45A so a 16A 3 phase MCB would be acceptable.
I have seen single pole (online) MCB’s is rated at 125A, they may go higher?
One of the reasons for an appliance to be a three phase load rather than a single phase is that a lower rated protective device is needed, and cable size can be smaller?
So if a load is 63A 3 phase, that means 63A per phase. A protective device above 63A would be needed.
So 63 x 1.73 x PF (1) x 400 = 43.5kW
So the Total load across the 3 phases is 43.5kW
And if I had a load of 43.5kw 43500/ (1.73 x 400 x PF1)=62A A 3 three phase 63A MCB would be needed
Thanks
I have left power factor a 1 for simplicity.
If I have a 63A three phase and neutral BS 60390 socket - I presume that means it can carry 63A per phase so 189A.?
But because of the displacement of the windings, you would never draw 186A at the same time as some phases will be in the negative cycle.
But theoretically it can handle 189A?
If I had load of 10kW on a single phase supply that would be 10,000/230 = 43.5A. So a 45 / 50 A MCB would be needed
If I had a load of 10kW on a 3 phase supply that would be 10,000 /( 1.73 x 400) = 14.45A so a 16A 3 phase MCB would be acceptable.
I have seen single pole (online) MCB’s is rated at 125A, they may go higher?
One of the reasons for an appliance to be a three phase load rather than a single phase is that a lower rated protective device is needed, and cable size can be smaller?
So if a load is 63A 3 phase, that means 63A per phase. A protective device above 63A would be needed.
So 63 x 1.73 x PF (1) x 400 = 43.5kW
So the Total load across the 3 phases is 43.5kW
And if I had a load of 43.5kw 43500/ (1.73 x 400 x PF1)=62A A 3 three phase 63A MCB would be needed
Thanks
Last edited: