relay weld test detection

Discussion in 'General Electronics Chat' started by Priyanshu Pandey, Aug 2, 2018.

  1. Priyanshu Pandey

    Thread Starter New Member

    Aug 2, 2018
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    Hi

    I want to do neutral relay weld detection . Any electronic circuit can I use to do it?
     
  2. panic mode

    AAC Fanatic!

    Oct 10, 2011
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    what is "neutral relay weld"
     
  3. Priyanshu Pandey

    Thread Starter New Member

    Aug 2, 2018
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    I had connected relays in line and neutral , and i want to check individually whether either of relay got stucked when i had given signal to open it?
    I can detect for line but i am unable to detect for neutral relay whether it is got stucked or not?
     
  4. jpanhalt

    Expert

    Jan 18, 2008
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    Is the supply to the load AC or DC? How many sets of contacts does the relay have?

    For DC, one simple solution is to put an LED and resistor across the relay contacts. When the contacts are open, the LED lights. If the contacts are welded closed or closed by the control voltage, the LED is out.

    If you will post the circuit you are using, a more detailed answer can be given.
     
  5. Priyanshu Pandey

    Thread Starter New Member

    Aug 2, 2018
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    Supply is AC single phase 230V across Line and Neutral . the problem with detection of neutral as it willl always have zero volt either relay closed or open , so how can i detect neutral relay welded or stucked?
     
  6. kubeek

    Expert

    Sep 20, 2005
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    You can use a relay with force guided contacts, where the main contacts are mechanically linked to the detection contacts, so if the main contacts get welded the secondary contacts will not switch over when you energise the relay. But they are not cheap and generally not suited for high loads.

    You could also add detection relays - one between the switched line and neutral, second one between switched neutral and line. One of these two will stay energized if one of the main contacts gets welded closed.
     
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  7. AlbertHall

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    Jun 4, 2014
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    You could connect a mains voltage neon (neon + resistor) across each contact. When both cotacts are open both neons will light up. If both contacts are closed neithe neo will light up. If only one contact is open just one neon will be lit - the one across the open contact.
     
  8. shortbus

    Expert

    Sep 30, 2009
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    Wouldn't the bigger question be, why is the neutral going through a relay? Single phase industrial/motor control usually doesn't use a relay in the neutral.
     
  9. AlbertHall

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    Jun 4, 2014
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    If the purpose of using two relays is to reduce the problems caused if one conract welds, then both cotacts could be in series in the live lead.
     
  10. Priyanshu Pandey

    Thread Starter New Member

    Aug 2, 2018
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    It is connected to neutral relay as line and neutral can be interchanged and in that case problem should not persist.
    I have problem associated with neutral relay as it have zero voltage on both side of relay contact whether contact is closed or open
     
  11. AlbertHall

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    Jun 4, 2014
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    See post #7
     
  12. Priyanshu Pandey

    Thread Starter New Member

    Aug 2, 2018
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    Can u please send the image of connection you have mentioned for post #7 so that it will be much clear.
     
  13. AlbertHall

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    The switches represent the relay contacts and the transformer represents whatever the relays are feeding.
    upload_2018-8-2_19-2-18.png
     
  14. Priyanshu Pandey

    Thread Starter New Member

    Aug 2, 2018
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    Thanks Albert for your interest shown and helping me out. I understood how to do through your circuit diagram.
     
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