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Thread: push button contact

  1. #1
    Join Date
    Apr 2017
    Location
    Ulsan, Korea
    Posts
    3

    push button contact

    Dear all,

    I have been working as an instrument engineer in Refinery and chemical factory.
    As you might know, we use push button switch to stop machine or process.
    We use NC because safety. However sometimes machine or process would be stop by push button contact failure.
    So, we would like to improve push button reliability using voting contacts or push button.

    If you know standard or code where i refer to apply, please rely my thread..
    And I would like to discuss about how to solve this matter.


    thank you for reading...


    Young from Korea

  2. #2
    Join Date
    Sep 2008
    Location
    UK
    Posts
    10,228
    Quote Originally Posted by webfst View Post
    Dear all,

    I have been working as an instrument engineer in Refinery and chemical factory.
    As you might know, we use push button switch to stop machine or process.
    We use NC because safety. However sometimes machine or process would be stop by push button contact failure.
    So, we would like to improve push button reliability using voting contacts or push button.

    If you know standard or code where i refer to apply, please rely my thread..
    And I would like to discuss about how to solve this matter.


    thank you for reading...


    Young from Korea
    Try a Pilz relay.
    Si hoc legere scis nimium eruditionis habes.

  3. #3
    Join Date
    Dec 2007
    Location
    NE Nebraska
    Posts
    33,527
    Quote Originally Posted by webfst View Post
    Dear all,

    I have been working as an instrument engineer in Refinery and chemical factory.
    As you might know, we use push button switch to stop machine or process.
    We use NC because safety. However sometimes machine or process would be stop by push button contact failure.
    So, we would like to improve push button reliability using voting contacts or push button.

    If you know standard or code where i refer to apply, please rely my thread..
    And I would like to discuss about how to solve this matter.


    thank you for reading...


    Young from Korea
    What is reason for contact failure? Make sure they are being used within their ratings. If they are really inexpensive devices, upgrade to better quality devices. If mounted on the machine, vibration maybe contributing to deterioration, but again maybe better quality device will last longer.

  4. #4
    Join Date
    Aug 2004
    Location
    Northern illinois
    Posts
    15,657
    How often does this happen?

    It could be that you are using poor quality contact pushbuttons. If so, changing to a better quality of pushbutton may solve your problem.

    Maybe there is some environmental factor that is causing the failure. Could be corrosive fumes, even vibration. Maybe sealed contact blocks would help with corrosion. Vibration is a little tougher but you might be able to find mounting locations that are less susceptible to vibration.

    It could also be that you are using them outside of their ratings, although that seems unlikely.

    Without more information it is hard to give you any good advice.

    I don't know how going to some kind of voting scheme is going to solve the failures. Better to fix the problem than to mask it.
    Bob

  5. #5
    Join Date
    Sep 2008
    Location
    UK
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    10,228
    Quote Originally Posted by petersonra View Post
    I don't know how going to some kind of voting scheme is going to solve the failures. Better to fix the problem than to mask it.
    Voting scheme?
    Si hoc legere scis nimium eruditionis habes.

  6. #6
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    18,377
    Quote Originally Posted by Besoeker View Post
    Voting scheme?
    One switch with three contacts or three switches ganged together with one contact each.
    Switches feed into logic that determines the state of the switch by either all three or any two out of three being in a particular state.
    Majority rules.

  7. #7
    Join Date
    Sep 2008
    Location
    UK
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    10,228
    Quote Originally Posted by GoldDigger View Post
    One switch with three contacts or three switches ganged together with one contact each.
    Switches feed into logic that determines the state of the switch by either all three or any two out of three being in a particular state.
    Majority rules.
    Thanks for that. New one on me.
    Proves that I'm not a specialist who knows absolutely everything about absolutely nothing.................
    Si hoc legere scis nimium eruditionis habes.

  8. #8
    Join Date
    Dec 2007
    Location
    NE Nebraska
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    33,527
    Quote Originally Posted by GoldDigger View Post
    One switch with three contacts or three switches ganged together with one contact each.
    Switches feed into logic that determines the state of the switch by either all three or any two out of three being in a particular state.
    Majority rules.
    Does the logic warn you if one of the contacts isn't working so you can repair it before too many of them cause a total failure?

    Never heard of that scheme myself, but can see it used on something very critical in nature.

  9. #9
    Join Date
    Dec 2012
    Location
    Rocky Mountain Region
    Posts
    265
    Quote Originally Posted by Besoeker View Post
    Thanks for that. New one on me.
    Proves that I'm not a specialist who knows absolutely everything about absolutely nothing.................
    Nice play on words.

  10. #10
    Join Date
    Dec 2012
    Location
    Placerville, CA, USA
    Posts
    18,377
    An Engineer starts out knowing a lot about a few things and as time goes on knows more and more about less and less until he knows everything about nothing.
    A Salesman starts out knowing a little about lots of things and as time goes on he knows less and less about more and more until he ends up knowing nothing about everything.
    A Purchasing Agent starts out knowing a lot about a lot of things, but through continuing interaction with engineers and salesmen ends up not knowing anything about anything.
    (Sign over Purchasing Agent's desk)

    Sent from my XT1585 using Tapatalk

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