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Circuit failure indicator

Discussion in 'General Electronics Discussion' started by Michael S Payne, Sep 3, 2016.

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  1. Michael S Payne

    Michael S Payne

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    Jul 21, 2015
    I am building a machine with about 15 different components that must all be working for the machine to operate. If the machine failed to operate, I would like an led to illuminate and inform me which component is failing. It don't think I can draw power through most items, because some of the components are coil operated silinoids, relays, etc... so the extra amperage would fry the coil, I would think. Obviously on a 20 ampo line with a 12 amp motor, I could draw through the item. I don't know if this information is germane, but I figured it would not hurt. I have attached an image to give this info as a visual in case I am not clear. Broken part identification light.jpg
     
  2. Alec_t

    Alec_t

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    Jul 7, 2015
    As you don't specify all the components there is no obvious solution. It seems each component would need its own failure-sensor. The type of sensor would depend on the type of component. The sensors could operate respective LEDs. It doesn't sound cheap or simple. One name for it is 'failure monitoring system'.
     
  3. Michael S Payne

    Michael S Payne

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    Jul 21, 2015
    Thank you for the reply Alec_t Let's simplify the problem and use the component I had in mind. in the drawing. It is a solenoid valve (120VAC 2Watts) How would I get a single LED to light up if that coil fails? Also, while the led I listed is 120v, that is not germane, as I can as easily use any led, relays, and other solutions I understand. So, with just a one component circuit as in the diagram, can you offer a solution? I can multiply the solution once I understand how to skin this problem.

    Thanks, Mike.
     
    Last edited by a moderator: Sep 4, 2016
  4. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    You could use a neon light across a coil.
    The 120v solenoid or relay coil would work normally, but when the spool burns out, the neon (parallel to coil) would light.

    Similar to how an illuminated light switch works.
     
    CDRIVE and hevans1944 like this.
  5. Alec_t

    Alec_t

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    Jul 7, 2015
    If you want just to detect coil failure you could use a Hall sensor to measure the coil current, then a window comparator would let you know if the current was too low (coil open-circuit) or too high (shorted turn). Alternatively you might be able to arrange that actuation of the solenoid would also operate a microswitch connected to an alarm circuit triggered by failure of the microswitch to open/close a circuit.
     
  6. Michael S Payne

    Michael S Payne

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    Jul 21, 2015
  7. Tha fios agaibh

    Tha fios agaibh

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    :rolleyes:You could use a reed switch where that red cap is. You'd have to alter it to suit.
    The magnetic field is quite strong on asco valves.
    (Or, as$hole valves as we used to call them).
     
  8. Michael S Payne

    Michael S Payne

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    Jul 21, 2015
    Very nice, reed switch sounds like a good idea. I thought the solutions wer egoing to be something I can universally apply; however, I now see why not seeeing the entire circuit adds to the problem. What about a contactor relay that is stuck but the coil is good, or the A/C motor said relay turns on? Any ideas for these items lighting an led if they fail? Thanks, MIke.
     
  9. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Best is to just program fault logic on a plc that can turn on a light or alarm
     
  10. Michael S Payne

    Michael S Payne

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    Jul 21, 2015
    Sounds good, I will do some reading and learn the PLC. I have been intent on learning how to utilize digital circuitry anyways. I am limited quite a bit by using all mechanical relays, etc.. Thank you very much for your advice.
     
  11. Alec_t

    Alec_t

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    Jul 7, 2015
    You would use the logic Fault = "contact energised AND coil de-energised" OR "contact de-energised AND coil energised". Probably a couple of voltage-dividers and an XOR gate would suffice for that.
     
  12. Michael S Payne

    Michael S Payne

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    Jul 21, 2015
    This has been great, I am glad I asked, instead of looking at my schematic drawing while my eyes glossed over. Now for the hard part, studying up on what you folks have pointed me to, and trying to learn and apply it.
     
  13. Bluejets

    Bluejets

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    Oct 5, 2014
    neon will glow whenever coil is energised.
     
  14. Kiwi

    Kiwi

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    Jan 28, 2013
    Sorry guys, but I'm going to attack this from a different direction.

    Above suggestions indicate the electrical operation of the coil, but don't indicate the mechanical operation of the valve.
    My suggestion would be to put a pressure switch on the output of the solenoid valve to make sure that it has opened and fluid at the correct pressure is flowing through it.

    I would also probably put a neon across the coil winding to indicate power supply is active.
     
  15. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Brightness would depends on the load and resistor used with the neon but yes your right.
     
  16. Tha fios agaibh

    Tha fios agaibh

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    The cost of PlCs are so inexpensive now a days that it's a no brainer.

    You could program a circuit that sends a fault if a relay output is energized and its auxiliary contact is not made.
    How about a fault if the auxiliary contact is made and output is not called for?

    Then program another rung that sends a fault if flow (or whatever) is not seen a second or two after energizing a valve.

    The possibilities are endless.
     
  17. Colin Mitchell

    Colin Mitchell

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    Aug 31, 2014
    Simply wind a number of turns around a reed switch and add it to the line.
     
  18. Tha fios agaibh

    Tha fios agaibh

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    Aug 11, 2014
    Entry level Plcs cost less than $100.
     
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