On 2014-10-19, Lucky Dave wrote:
Have three phase 240 volt in my shop. Need to change plug to 240v single
phase
Does your machine need to have a neutral lead to run 120VAC
subsystems (like coolant pumps or lamps), or is it a pure 240VAC load?
If it is a pure 240 VAC load, then pick any two of the three
phase leads and you will have 240 VAC between them. (Of course, be sure
to have the safety ground connected, too.) If your three phase is
open-delta then two of the phases are real, and the third phase is
virtual, so be sure to pick one of those two phases. Usually, I think,
you will find that one end of the two real phases is grounded, but if
there is also a setup to give you 120 VAC as well, then not so.
If you need a true 120 VAC neutral, you probably have problems,
unless you have a step-down transformer to run the 120 VAC loads.
For three phase, you could have either of two different
connectors, BTW. One (with only safety ground and no three-phase
neutral) will typically have four pins arranged in a circle (for
twist-lock connectors). But if there is a three phase neutral *and* a
safety ground, there are connectors which have the four pins in a circle
and a single round pin in the center. In that case, the round pin will
be the ground, and one of the four will be the neutral.
First -- get a connector to plug into the existing outlet which
you have, and open it up. One of the screws should be painted green
(this is the ground, and should get a green wire from the machine you
are connecting. Then two of the wires from the machine should be black
and red. (White, if present, is usually neutral, but is sometimes used
as a phase when there is no neutral) Usually, you will find letters
stamped near where the wires go in in the plug. "X", "Y", and "Z".
Probably you should use the "X" and "Y" as your 240 VAC. But *always*
remember that you need a green from the green screw on the connector to
the frame of your machine. tool.
Or -- you *could* hire an electrician to run a 240 VAC feed from
your breaker box to where you want your new machine to plug in. If you
feel uncomfortable working with this, an electrician is good piece of
mind.
Good Luck,
Don.
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