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Thread: Lincoln K240 info

  1. #1
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    Dec 2014
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    Wasilla, Alaska
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    Lincoln K240 info

    I am trying to connect a Lincoln Weldanpower 225/210, AC/DC, CV/CC SN A1052458 Code 8928 to a Lincoln LN7 GMA Code 7930 wire feeder. Lincoln says I need a "K240, obsolete, no longer available". I have no idea what a K240 is or does. can anyone provide any info, a work around, a substitute, or a used unit or parts? I have justified this project with my CFO for use around the ranch, since I have both machines with very little money invested, she has approved. I would be very grateful for any info, a source for a K240 or substitute, even a crayon schematic on a paper napkin. TIA.

  2. #2
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    Mar 2010
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    Re: Lincoln K240 info

    The K240 is a 600 amp contactor assembly. Since the the welder is hot all the time.
    The contactor will make the weld circuit cold. Operates off of the 115 volt plug.
    The LN 7 needs 115 volts to operate and can turn the contactor on and off so the welding wire is hot only when feeding. For what you want to do you have two choices.
    1, just power the LN7 from the welder and use the wire hot all the time.
    or 2, find a large relay (contactor) that can make and break 300 to 600 amps. DC
    you can use a smaller one but you must size it to what you are welding.
    You might look into the replacement contactor sold by profax / lenco for use in the LN25 wire feeder. its is a DC contactor around 300 amps. The coil needs 12vdc. so you can use battery voltage. But as you are building it . power the contactor on 12vdc and measure the temperature of the coil. If it gets hot you will need to lower the voltage to the coil. One way is to switch in a resistor and drop the voltage to 8 volts or less a 1/2 second after applying the full 12 vdc to pull in the contactor.
    This is called pull in and hold voltage. Can be done with an electronic timer or the old school way we modified a control relay so one arm made contact just before the other. adding or removing the resistor. over all you are trying to make the LN7 work like a LN25.

  3. #3
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    Re: Lincoln K240 info

    ccawgc, Thank you for your reply! I gather from your post I need a 2 pole 300 amp contactor, is this correct? Contactors are available in 12 VDC, 24 VDC and 115VAC. 115 VAC is available from my Weldanpower and the LN7 has a 120 VAC cord also, otherwise I could install 115VAC to 12VDC or 24VDC transformer for a DC source. I'll see if Lincoln can supply a schematic. Let me know if I am wrapped around the axle here.

  4. #4
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    Re: Lincoln K240 info

    The contactor used in the LN25 is a single pole. which you can get from profax cheaper than from Lincoln. Or any contactor you can find. you can use a step down transformer of any voltage to match the coil voltage of the contactor you select.
    You might try a smaller amp transformer 2, 3 or 4 pole and place them in parrallel.
    4x 100 will get you 400 amps. won't last a long as a 400 amp single pole for DC current. but will work for a while. DC contactors have magnets to suppress the arc flash when the contacts open.

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