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	Subject - Single to 3 phase power conversion joshzee I am doing some design work for a customer and when I asked him to specify the power source he was using he told me that it was going to be a 25 KW power supply. Then I was told that he was going to hook up 3 single phase transformers in a delta formation to create 3 phase power, and that he was going to control each leg of the power separately, supplying different power to each leg. My question's is this possible? I thought that when using 3 phase power you had one controller for the whole setup, what he was describing seemed like single phase power to me. Let me know what you think, and also send me any links you have that describe 3 phase power very well. Thanks for your help in advance, Josh JimmyDee Thanks for posting this question. I think we need a little more information to give a good answer. I'm not sure what he means when he is going to control each leg separately and supplying different power to each leg. If it is to be three phase that is being utilized, all three legs would be controlled at the same time. Give us some more detail. Jim Scott Vickrey I'm lost too Josh please elaborate. joshzee Now you guys know how I have been feeling for the past week. It may be helpful to tell you that this setup is going to be used in a resistance heating setup for a furnace. The way we normally design this kind of arrangement is to provide 3 separate electrode points within our element assembly where each of the three phases of the transformer can be attached. When we do this there is normally just one controller which controls the entire element assembly. The customer wants to control each of the three legs separately, which leads me to think he wants single phase power for all of these legs, but he made sure to say that he was going to hook up three separate single phase transformers into a delta formation creating three phase power. This guy could just be way off, for all I know he is a salesman with no electrical background at all, and the more I think about this problem I think that this may be the case. Thanks again for your help. JimmyDee I wonder if he wants to stage each phase separately. Don't know why he would want to do it, but he may want to have three separate heating systems. One system on each phase of the three phase system. The salesman, not being an electrician, may be expressing it wrong and means what I have just stated. Jim joshzee Jim, If he does want to stage each phase separately, would the connections still be the same as normal 3 phase delta power? Josh JimmyDee Yes the transformers can be hooked up delta. You would need three sets of 2-Pole contactors. (you can use 3 pole) You would then need to connect each stage to: (1) phase AB; (2) phase BC; and (3) phase AC. The load side of the contactors to each single stage of the heater system. Jim