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George Carlson phase convertor help?

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  • George Carlson phase convertor help?

    hey all. this is my first post here. so im the newbie!

    anyway, first a bit on me. i am a grinderhand. i now work as a realtor, but i used to do percision/finish grinding for a tool and die company specializeing in PM tooling for the big three.

    i have a small mill, lathe and a tig rig.

    i recently bought a boyer schultz 6X12 surface grinder. problem is i need to power it using single phase 220. my tig welder has the only 220 plug in the house. so i will find a plug that fits its special outlet, and hook that up to a phase convertor.

    i want to build georg carlsons phase convertor. the "Simple Static Phase Converter"

    see the info here-

    can someone here explain to me what he means by this statement-

    """4. In the top drawing, the potential relay uses AC Neutral as a reference. DO NOT USE SAFETY GROUND INSTEAD OF AC NEUTRAL, IT CAN KILL YOU!"""

    is ac neutral the line on 220 power that does to carry power?? like out of the three wires 2 are power and 1 is neutral???

    what is the "saftey ground" he says not to use???

    im confused. help if you can please.


  • #2
    The safety ground is the one which connects the case, enclosure, box, frame, etc. - all the stuff you might touch - to ground. That way if there's a fault and a live wire touches any of that stuff, it will short to ground and blow a fuse or breaker rather than leaving the case, enclosure, box, frame, etc. live, just waiting for you to touch them. Normally, if there's no fault, none of that stuff is live, of course, so the safety ground doesn't carry any current. In normal operation your neutral does carry current. It's an active part of the circuit.

    The safety ground has green insulation or is bare. Your neutral is white. That's the color code in North America, I believe. Europe is undoubtedly different. Your hot wires are each 120 v with respect to the common. The hots should be color coded black and red. The common, the white one, should be grounded at the service entrance to the building but nowhere else. That's the source of much confusion - the common (white) and ground (green or bare) are at the same potential - ground - and so show exactly the same voltage when read with a meter, but they do different jobs.