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Found out what a mag starter is for...

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  • Found out what a mag starter is for...

    Well, I've been fooling around with the lathe this evening. Changed the location of the switch. It was in the cabinet so I built a rig to put in an up top position like a south bend. Then I chased down the right size belt, got the motor mounted and everything in order. So I figure as a starting point I'll just wire it as 110, hook a cord up to it (10 ga. grounded, I'm dumb but not stoopid) and plug her up. Well. lots of sparks, arcing and ozone smells. I guess I get it now.

    Anyway, my starter has a set of contacts labled T1, T2 and a set labled L1 and L2. I was thinking that L2, L1 was "load" but the power wires coming in are hooked to them. It was originally 3 phase. Thanks for the info on the drum switch and sorry if this doesn't warrant another thread.
    I did get it running and ran through the speeds from 250-1500. Didn't try the back gear. (It has one of those sheave type variable speed deals) Everything seems to be OK if I can just get the power figured out.

    Hoffman in Warner Robins Ga

  • #2
    I assume that L is for Line

    Now if some can come up for the T.


    • #3
      It's not a starter it's an overload deal with the heaters. I thought it was a starter because it resembles the one on a compressor I just finished.
      Just remembered I left the compressor on...

      Hoffman in Warner Robins Ga

      [This message has been edited by hoffman (edited 11-25-2004).]


      • #4
        Normally, L denotes input side of contactor or overloads, T denotes output side headed to motor. On the bottom of a overload it is labeled T, on the bottom of a starter labeled T.. so?

        Motor internal leads are labeled T1,2,3,4,5,6 so on.. But that does not mean always they hook to the same number.

        With a contactor, you also have pesky coil wires to contend with, with 220 240 systems they are usually 220/240 coils fed off the top of the L1, L2 L3 input side. Sometimes they are 120 with internal taps to change the voltage to 120 "or" 220 volts. If wired wrong they will immediatly tell you one way or another by blowing or smoking. You need replacement parts then.

        About 30 years ago I was a young apprentice. Claude a Vietnam vet I worked with for years had wired a starter up on a lift pump at a sewage plant. Him being a young non-properly educated electrician he wired the new one just like the old one. Unfortunatly it had a 480 coil on the old one and the new one had a 120.. when he applied power everything was just fine, when he flipped it on it blew the lid off. I took off running, IN my young mind I decided I had to go back and get Claude. As I went into a left hand turn we collided. Evidently he survived in Vietnam by running and following the officer. No laughter, but sheer terror in his eyes. If He'd had a M16 people would have died.

        Overloads are sometimes small items usually on the bottom of a contactor, they can be thermal or electronic. Usually the cheap ones work like a thermostat with bimetal contacts. When the properly sized wire "heaters" exceed the cooling-heating of the designed amperage they break the power to the coil shutting the system down before it burns out the motor windings. Sometimes overloads can be by themselves, Sometimes they are incorporated into the motor with a red button sticking out to push to reset. Sometimes they are non-existient as in Chinese motors. Sometimes they have a amperage knob on them to set for the size of the motor. I sold several recently like that. Pushbutton reset overloads with current setting knobs.

        Controls descriptions, two wire are the simplest, the coil in the contactor is turned on and off by a returning hot wire of the proper voltage, two wire denotes how many you need at the switches. During power blinks or brown outs they come back on when the power does.

        Three wire systems are a push button start and a pushbutton stop.
        The power goes out to the stop, a wire returning from the stop goes to a Normally open "holding" or "latching" contact on the relay or starter and on other side to coil, a wire from this point goes back to the exit side of the start button. The start button is fed from the stop button. When the start button is depressed, the NC contact stop is made up the coil is momentarily energized and closes the relay latching contacts to the coil from the stop.. this continues the circuit after the start is released.. WHen the stop is pushed, the circuit is broken and the coil opens up. If the power blinks, or goes off the contactor should not reclose but be "off" You need "3" wires going to the start-stop station, a Normally open start and a Normally closed stop.

        Things to be concerned with the Home shop Machinist, Arc quenching. Not all switches are the same rating as a motor contactor switch. They have internal paddles and points to slow and dispel the arcing of opening and closing a switch. A light switch thou it will work for a while will burn out. It has no high ampacity starts engineered into it's contact design. ALL motors started across line develop up to %600 of normal current during the first milleseconds of starting.

        A fractional horsepower starter-contactor with overload is the proper way to start/stop a motor. BUT, I have a light switch or two in my shop so they do work for a while.

        If you want your device properly identified, you will have to post a picture where we can all look-see.