converting delta to wye

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Hi,

my father recently purchased a used piece of equipment. After plugging it in one of the relays stuck. A repairman said it was because he had the wrong form of 3 phase power. I'm a new to this but from the best I can understand, I think he has 3 phase delta and the machine requires wye.

Is there an easy way to test this, and what is the easiest fix?

Someone told him the power can be converted by using three transformers but I havne't been able to find any information on how this is done, or if it's even possible.

Any help would be greatly appreciated.

Thank you,

Dan

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Try to find first the equipment specification. Miswiring from delta to y causes an overload of 1.73 to the equipment. Gene

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Please provide the information from the equipment name plate and I do mean all of it. Is the equipment is 240 volt, 3 phase or is it 208 volt three phase or perhaps something else all together. Also provide the configuration and voltage of the buildings power system.

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sounds like your description of delta 3 phase with the neutral tap on one leg. From the way it was described to me, one leg measures 220 and the other two measure 110. Does this sound correct?

The machine (an older mori-seiki cnc lathe) says: Phase: 3 Wire: 3 Volt: 220 Cycle: 60 Hz Load: 37.0 KVA

It came from an auction and apparently it originally had a box containing transformers that were sold seperately.

Does the nameplate describe the power requirements? Also is it easy to measure the source? I can check with a voltmeter. Thanks a lot for the help.

Dan

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The problem that you have, if any, is that the voltage of the equipment is 220v and not 240v. Normally this is not a problem, but since it is CNC equipment it could be. Usually this occurs if the equipment is rated 208v.

You will need to obtain 3 buck/boost transformers or find a vendor that produces one in one enclosure.

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/- 240V -\ A - 120V - N - 120V - B with 3 wires: A, B, N then your supply is single phase.

Looks like the lathe requires 3 phase that is supplied as a delta (as Don said it the machine doesn't require a delta, but that is how 240V is normally supplied). Essentially repeating from the post above, if you measure voltage between any 2 of 3 hots it should be 240V (there are 3 measurements).

Deltas mostly have the center point one one side as the neutral and grounded. From 2 of the hots to neutral the voltage is 120V. From the

3rd hot to neutral the voltage is 208V - the high leg, orange wire, B phase in but old panels.

3 phase 3 wire shouldn't require a neutral.

It is possible the transformers were necessary but I would doubt it. There should be terminal bars for transformer connection if they are required. There should be a control transformer to supply relays and the numerical control. Be careful - with not a lot of effort the computer control could wind up fried.

Might be worth asking the repairman what he was talking about now that you are a 3 phase expert.

My understanding of the difference between 240V and 220V is that 240V is nominal at the supply (service) and 220V is nominal at the load. The lathe manufacturer sounds non-US which may be different.

bud--

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Taking the obvious step of Googling Mori Seki turned up Mori Seki - US

Mori Seki - world
likely know about them, but just in case...

------------------- Warning - way of topic - some may be interested in Googling "failure" using "I'm feeling lucky"

bud--

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It does appear that he is trying to run a 3-phase device from a center tapped single phase supply. I happily concur with what you have said.

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Beauty.

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I don't understand it enough to explain it. But I found a web site that I think will help.