rewinding 110v contactor coil for 220v help

Discussion in 'The Projects Forum' started by kleintoren, Dec 28, 2010.

  1. kleintoren

    Thread Starter New Member

    Dec 22, 2010
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    I have a Square D 8910DPA23S41 Contactor with a removable 110v/50hz.120v/60hz coil - how many turns do I need to rewind the coil for 22/240v
     
  2. #12

    Expert

    Nov 30, 2010
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    Your question does not make sense in several ways. Do you want 22hz/240v? Do you want 22v and 240v at unknown frequency? and finally, why not just buy a replacement for the replacable coil?
     
  3. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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  4. thatoneguy

    AAC Fanatic!

    Feb 19, 2009
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    Take the contactor apart, unwind the current winding, making sure you have an accurate count. Keep the unwound wire neat and tidy.

    Throw away the destroyed contactor, buy one rated for the voltage you use, and re-purpose the magnet wire you salvaged into inductors or motors. :D
     
  5. Hagen

    Active Member

    May 8, 2010
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    To rewind coil for 240 volt,60Hz, you would have to double the turns and use a wire with half the original cross sectional area (about 3 AWG sizes)
     
  6. marshallf3

    Well-Known Member

    Jul 26, 2010
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    It's entirely not worth it when you can buy one for next to nothing, the cost of the magnet wire alone will cost you more than the proper replacement and even one tiny kink can cause a shorted turn and then you've got history on your hands.

    If the coil is removable you may be able to just replace that part for less but then you don't get the advantage of all brand new moving parts and contacts. Of course I'm not one to talk, I've got plenty of extras sitting around (all 120V GE's though) and if necessary I may move parts from one to another just so I don't have to take an entire motor control bucket out of a distribution panel.
     
  7. Kermit2

    AAC Fanatic!

    Feb 5, 2010
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    Use a resistor of the appropriate wattage and drop half the AC voltage.

    120 V coil will work on 240 with no problem. even with a lower freq. a proper resistor value can be found to let the coil work within its current rating. At low freq a different winding scheme might be needed to keep the relay from chattering. 25Hz equipment still exists but is rare nowadays. What the heck are you doing anyway?
     
    Last edited: Dec 28, 2010
  8. marshallf3

    Well-Known Member

    Jul 26, 2010
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    That could be done but a lot of these contactors take a fairly large amount of current. They are in essence relays but if he's dealing with a higher power one that started off with a 120VAC coil it will likely want at least an amp or so to energize and hold, I've got some that pull 3A on the coils but they're switching 3 phase huge motors.

    Square D is a reputable company with distributors all over the world, finding a replacement coil or complete unit shouldn't be a problem.
     
  9. Hagen

    Active Member

    May 8, 2010
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    The member asked a very simple question, that is, how would you alter the winding data to change a coil's rated voltage from 120 to 240. Whether it's worth the time and trouble to actually do it should maybe left up to him. Maybe he has all the time and patience in the world. Maybe he just enjoy's working with his hands. Good grief! Maybe he doesn't even plan on actually doing it, but wanted to know what would be involved.
     
  10. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Simple, measure the impedance and current draw at 120V then duplicate it for 240V.

    There's no way you can can count the original windings and AWG of the wire then come up with what you'll have to replace it with unless you go through a lot of formulas. If there's room go down by 2 - 3 AWG gauges and wind around 50% more turns on the form as a starting point. Measure everything again and you might be good to go.

    How would you do it, considering the laws of inductance and core permeability?
     
  11. jpanhalt

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    Jan 18, 2008
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    I don't get your point. Was your comment intended to help the OP?

    John
     
  12. Hagen

    Active Member

    May 8, 2010
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    There are no complicated formulae in this case. Doubling the turns and decreasing the wire size by 3 AWG sizes will exactly double the working voltage (assuming the same applied frequency).
     
  13. Hagen

    Active Member

    May 8, 2010
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    I guess it just struck me as odd that instead of answering a simple question, most of the replies seemed to suggest that is was a question not worth asking.
     
  14. Hagen

    Active Member

    May 8, 2010
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    In my trade we often deal with contactors,coils, etc. It is quite common for a coil to be rated as dual voltage, and have 4 terminals. Each dual voltage coil has 2 identical windings which can be connected in parallel for the low voltage(120 for example), or in series for high voltage(240). The iron is equally saturated in either case, since the ampere*turns remains the same. This is my reasoning.
     
  15. marshallf3

    Well-Known Member

    Jul 26, 2010
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    Every motor control bucket I have has its own 480:120 stepdown transformer to go out to the start/stop switches and the contactors only have 120V coils. Mind you though this whole building was supplied by GE, I can even copy a job # off the inside of anything in there and they still have all the build sheets for it. Nothing's really custom but it's sure nice to see a company that keeps track of records for over 40 years and is willing to send them to you at will should you need them.

    If he wants to try and wind it on his own I made my suggestions, if he wants I'm sure Square D might even ship him a free sample of a replacement coil designed for 240V/50Hz.
     
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