To clarify what I meant about your response, at 120V you can draw 200A or at 208V you can draw 200A not both at the same time and the same goes for the 120/240 1Ø or 3Ø, 200A at 120V or 100A at 240V. As you stated, of course all this is in theory since it all depends on the size of the transformers on the utility pole.
I am basing my questions on the idea that if you take (3) 1Ø transformer all of the same KVA rating that produce say 20A on the load side that you will get the following with the different configurations:
(Qty. 1) 1Ø transformer will give 20A @ 120V or 10A @ 240V 1Ø
(Qty. 2) 1Ø transformers wired into an Open Delta will give 20A @ 120V or 10A @ 240V 3Ø
(Qty. 3) 1Ø transformers wired into a Wye will give 20A @ 120V or 20A @ 208V 3Ø
All this as stated previousy that it is at one voltage or the other, not both at the same time.
Re: 200 amp Service 3 Phase#66670 06/14/0606:10 AM06/14/0606:10 AM
A 200A service is one that can nominally supply 200A on each of the incoming ungrounded conductors. I say 'nominally' because the ratings of the transformer and the trip curve of the main OCPD come into play, but in general this means that you have service conductors with an ampacity of 200A and OCPD with a trip rating of 200A.
In the case of 120/208 3 phase 4 wire wye, a 200A service means that on any leg you can have 200A of current flow. You could have a total of 72KVA delivered as 200A on each of 3 120V line to neutral loads. You could have a total of 72 KVA delivered as 115.4A on each of 3 208V line to line loads. If you have a single load connected from phase A to phase B (or any other pair of phases), then you could supply 200A to it, but only deliver 41.6KVA. If you have a single load connected from phase A to phase B carrying 200A, and a single load connected from phase C to neutral, carrying 200A, then you will deliver 65.6KVA to the load. (As well as have 4 current carrying conductors....hmm, wonder what this says about 'full boats' )
For 120/240 3 phase 4 wire delta, again, on any leg you can have 200A of current flow. You could have a total of 48KVA delivered as 200A on each of 2 120V line to neutral loads, with the 'stinger' leg unused. You could also deliver 48KVA as 200A through any 240V load connected phase to phase. Finally, with a balanced three phase load, you could deliver a total of 83.1KVA as 115.4A on each of 3 240V line to line loads.
Re: 200 amp Service 3 Phase#66671 06/14/0609:02 AM06/14/0609:02 AM
Rhpope, the transformer configuration will not change the fact that 200 amps per phase is 200 amps per phase regardless of whether the loads are phase to ground, phase to phase, or any combination of them.
Radar, actualy it is more like 58% of a three winding Delta.