Weird continuous sound in relay

Discussion in 'General Electronics Chat' started by susannah, May 16, 2014.

  1. susannah

    Thread Starter Active Member

    Feb 14, 2010
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    I have Nagares RLP/4-12 12V-40A 3913 relay and it works okay but it also keeps funny electric buzzing noise all the time when it is powered. And i think i smell electric smoke when i try to use it too.

    I'm controlling it using 12V.

    Should i use less than 12V or whats going on?
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. MaxHeadRoom

    Expert

    Jul 18, 2013
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    If you used AC on a relay designed for DC the relay armature may not be constantly retained due to the AC reversing polarity every half cycle, so the relay tends to start to drop out at zero until the other half of the cycle attracts it again, this causes high current and chatter.
    AC relays have a shading coil to help retain it through the normal zero transition.
    Max.
     
  4. bwilliams60

    Active Member

    Nov 18, 2012
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    If you are using 12VDC, you either have insufficient current to power the coil, a bad ground or a bad coil in the relay. Is your power source capable of providing the correct voltage/current?
     
  5. MaxHeadRoom

    Expert

    Jul 18, 2013
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    The one thing with DC once it has pulled in it requires much less current to keep it retained.
    In large current devices, the supply is often reduced to reduce the P.S. current demand.
    Max.
     
  6. MaxHeadRoom

    Expert

    Jul 18, 2013
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    So what was the outcome?
    AC or DC that is the question.
    Max.
     
  7. susannah

    Thread Starter Active Member

    Feb 14, 2010
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    I was using 12 Volts DC. I don't know what happened but now it's working again.
     
  8. MaxHeadRoom

    Expert

    Jul 18, 2013
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    We even have healing powers from a distance...;)
    Max.
     
  9. alfacliff

    Well-Known Member

    Dec 13, 2013
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    if you pass the coil current through a normaly closed set of contacts, you have a clasic "buzzer" and that will make a noise as the relay pulls in, breaks the circuit, and drops out, making the circuit again.
     
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