Contactor Chattering in BASIC Practice Circuit for Course

Discussion in 'Homework Help' started by higgyhann10, Apr 10, 2016.

  1. higgyhann10

    Thread Starter New Member

    Feb 11, 2016
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    "Button 22/23 is an emergency stop. Directly after the emergency stop in the circuit there is a normally closed stop button. When pressing the button 12/13, contactor 1 and 3 are powered. This in turn powers light 10/11 and 18/19 while disabling contactors 2 and 4. By pressing the button 14/15, contactors 2 and 4 are powered. The normally closed gates in the branches of contactor 1 and 3 open, disabling those lights and contactors, while the lights 16/17 and 20/21 receive power. To reset circuit, press red button 6/7."

    I designed the attach schematic to fit the above circuit description. I understand that our schematic drawings are different than most and am not sure why, but they are simple. The rectangles are contactors and the switches will have be numbered "K---" depending on which contactor the switch is on. There are normally closed and normally open. The circles with the X are lights and there are also buttons, 12/13, 6/7 and so forth.

    My problem is that the second contactor chatters when I try to press the second button. Pressing the second button should turn off the first and third so that the second and forth can turn on but this doesn't happen. It only chatters. I can press the normally closed reset button 6/7 and then press the second button to turn on contactors 2 and 4 with their respective lights and vice versa. I'm taking it this means that the first and third contactors don't shut off so the second and fourth can turn on. I went through and tested continuity to make sure I wired it correctly and it appears to be good. When doing my voltage check, I found that when contactor 2 was activated with the second button, normally closed 71/72 and 62 of K2 all had a serious voltage drop from 120 to 6 or less. I'm not sure how to fix this or what the problem could be since my continuity check tells me that everything is wired correctly. My instructor said my schematic should work if correctly wired but didn't pay much mind to it so he could have been wrong. Will the schematic drawn function according to the description? If it should, what could be my problem? The only descrepencies I found were the aforementioned voltage drops with the normally closed switches. Thanks for your help!
     
  2. panic mode

    Senior Member

    Oct 10, 2011
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    your circuit looks fine and it should work. check youor wiring and pay attention to contact type and device numbering.
     
  3. higgyhann10

    Thread Starter New Member

    Feb 11, 2016
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    So I shouldn't have to press my 6/7 reset button between pressing buttons/ activating K1/K3 and K2/K4
     
  4. panic mode

    Senior Member

    Oct 10, 2011
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    no, pressing that button will turn off all four relays. if you designed this circuit, you would know that. ;-)

    if your wiring is correct:

    - pressing 12-13 button should turn on K1 and K3 and keep them energized even after you let go of the button. if K2/K4 were energized, both will go off.

    - pressing 14-15 button should turn on K2 and K4 and keep them energized even after you let go of the button. if K1/K3 were energized, both will go off.

    - pressing both 12-13 and 14-15 at the same time will energize K1,K2 but K3/K4 will be off.


    Are you familiar with idea of NO/NC contacts? can you disconnect K4 coil from circuit (but preferably leave in the circuit indicator that is wired in parallel with that coil)?
     
    Last edited: Apr 11, 2016
  5. higgyhann10

    Thread Starter New Member

    Feb 11, 2016
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    ***??
     
  6. panic mode

    Senior Member

    Oct 10, 2011
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    well... that is a sign of a good instructor... thumbs up :D
     
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