Step Down 240V to 208V

wrote:


OK, now I get it. BTW I have a open delta, 120/240 three phase here with the hot leg.
Never saw a 240 Volt closed Delta service. Around here true three phase is 120/208 or 277/480.
I have an old building in the middle of a residential neighborhood.
Thank You, Randy
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Randy wrote:

You have two hot legs and one high leg (Power leg, wild leg, or stinger). And one neutral. I prefer power leg. If I were to change out your service, the first thing I would do is check rotation at the service entrance with a phase sequence indicator and write it in the panel. Marking the position of the hot legs with an H and the power leg with a P and a CW for clock wise or a CCW for counter-clock wise. Also the date and my initials. I would check it again after I changed out the service, before I told the customer he could close his main.

If you have an Open Delta bank, you have true 3 phase. This connection is relatively inefficient where three-phase loads predominate since it has only 86.6% of the rating of the two units making up the three-phase bank. It also has only 57.7% of the three-phase rating of a closed delta bank of three units.
Don

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wrote:

I do not consider my Open Delta a true 3ph, as only the wild leg is 120 deg out of phase with the others. Although I'm sure it's better than the old rotary phase converter I had.
Thank You, Randy
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Randy wrote:

Randy you should go to
http://murrayranch.com/Electricity.htm
and take a look at the Open-Wye Open-Delta 120/240V at the bottom you will see phase angels and they are all 120 deg apart. You will see one side of the delta is gone but a,b & c phase are 120 deg apart. That Open-Wye Open-Delta 120/240V bank I show there has a 210 deg angular displacement.
Don

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How do you center ground a delta?
Wes
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Ground is center of one standard 120-0-120 leg. Ron
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roninchuck wrote:

Hi Group,
Thanks for all the informed replies to my question. I contacted Blodgett, the oven manufacturer and they said that replacing the heating elements would be the way to go.
I did learn an lot about delta and wye 3 phase from your replies!
Chuck
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