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| Subject - 3 Phase 230 volt or 208 | |
| trekstar | What is the difference between Delta and wye? Can any 3 phase equipment be installed on either one. Is one better than the other? |
| David Hyatt | Delta doesent have a neutral. Delta/Wye is what you want. |
| JimmyDee | Ditto to what David said. In addition, a Delta configuration is wired so the transformer coils will look like a triangle and the corners of the triangle will have the 3 phase line connecting to them. Output voltages are all the same and usually (in USA are 480 volts phase to phase, or 240 volts phase to phase) In a wye connected configuration the one end of the coils will be connected together at a common point and the neutral is connected their. The phase wires are connected to the other lead. The typical voltages on these configuration are 480 phase to phase and 277 from phase to neutral. Or 208 phase to phase and 120 volts, phase to neutral. The 480 wye is used for industrial and commercial because it can be adapted to lighting (277 volt lighting, 480 volt power) and the 208 wye is use a lot in small commercial or churches because it can be adapted to 120 volt lighting and 208 power for air conditioning. Large 3 phase power equipment like AC is much cheeper in 3 phase. Jim |
| JimmyDee | For further information on 3 phase transformers, here is an excellent link to a good explanation of hookup etc. CLICK HERE Jim |
| ricky | Don't forget to mention that high leg on wye 208 which SHOULD be marked with orange tape.Measures around 190v to neutral! |
| ricky | Sorry,dropped offline.Yea. what am I stupid.4 wire delta connected secondary has high leg.The midway point of one phase is grounded.Right? Ok for 208 but you gotta skip every third breaker for 120 volts.Oh back to the question.Yea,delta-wye. |
| JimmyDee | quote: No this is incorrect. (I see your retraction but added this for clarification) The wild leg that you are referring to is only in the open delta configuration. This is a 240 volt, 2 transformer, 3 phase system. 240 volts between phases A to B, B to C, and A to C. The voltage between A and the neutral is 120 volts, B and the neutral is 120 volts, (this transformer is wired just like a typical 240/120 transformer) and the C phase is 277 + or- volts to the neutral and is orange. Back in my day it was red. I'll see if I can scan a picture of an open delta hookup and post it on my web page. Jim |
| boccinono | Trekstar, to answer your question. NO! Any 3 phase equipment can not be connected to any 3 phase system. It depends on what the voltage of the equipment. On a delta system, in every case I have seen, the B phase is the high leg, with voltage ranging from 187 to 208 to ground, and is identified by orange tape. With a red tape mark on B phase. It is usually, but not always, a wye configuration, with 120 volts to ground. |
| JimmyDee | I guess I assumed trekstar would realize one could not hook up a piece of 3 phase equipment that was of a different voltage. Yes a piece of 3 phase equipment can be hooked to either a wye or delta and without knowing the difference. The only way it would matter is if the equipment needed a neutral for some reason but I've never seen that. Boccinono, I don't want to get into an ****ing match with you as to whether it is the A, B or C phase on an open delta system that gets the orange tape as long as we are in agreement as to the neutral is the grounded center tap of one of the transformers and the wild leg voltage is measured to the extreme leg of the second transformer to that neutral. |
| boccinono | Jimmy, not getting into a ****ing match. That has just been my experience. Sorry, if i offended you. I was just giving my experience with the system. |
| JimmyDee | You may be correct about the voltage to the neutral. I can tell you one thing, a refrigerator and microwave last about 45 seconds before smoke leaves the equipment when someone uses the wild leg slots to get a couple of additional circuits to a church kitchen remodel. The money they saved on the electrical was spent replacing the refrigerator and microwave. The guy said he thought it was funny that every third breaker slot was empty. BTW no offense taken. Jim |
| David Hyatt | By code the b phase supposed to be the highleg, but don't count on it. I have seen it on c phase also. Orange tape is to identify high. |
| hivolt | in allegany power service area the utility requires the hi leg to be in the right hand terminal in the meter, however the national electric code requires it to be in the middle position. |
| hivolt | in the middle position in the electrical panel |