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Simplest electromechanical relay circuit

Discussion in 'Electronic Design' started by Don Kuenz, Dec 22, 2013.

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  1. Guest

    In Dubai, is that a problem?
  2. Robert Baer

    Robert Baer Guest

    * Read "Coil resistance" in the Coil Data section (page one,top - where
    it cannot be ignored or "lost").
    The rest of it is symple Ohm's law to determine current, then power draw.
  3. Don Kuenz

    Don Kuenz Guest

    Thank you for this and your earlier advice about what it takes to burnup
    (melt the coil winding of) a relay.


    Merry Christmas to all who read this!

    __/ \
    / \__/
    \__/ Don Kuenz
    / \__
    \__/ \
  4. Guest

    Ummm, actually, not quite. If you read some of the peer reviewed literatureoutlining hardcore relay design details like contact materials, pressure and over travel, among many others, for DC relays anyway, relay life is actually improved by the redistribution of contact material by inductive flyback, tending to repair the erosion caused by the closure. Note the operative phrase is "is improved" and not "may be improved." Generally it is safe to say that if the relay is used within its inductive rating (or derating as the case may be) you can expect the full operational MTBF, however it is spec'd like 10,000 electrical actuations at full load, 1 million mechanical actuations, etc., without possibly making things *worse* with a snubber.
  5. Den mandag den 23. december 2013 21.25.52 UTC+1 skrev John Larkin:
    The could probably tell just by the sound when a relay was worn and soon
    needed replacement
    They are probably all behind barbed wire fences now, We got guided tours
    when I was in school

  6. Guest

    Nonsense, you can switch any side you want.
    Okay, that part is right.
  7. Guest

    Ummm, that is not really true. The relay is designed so that it just operates at rated voltage and maximum temperature (50-85 oC range). The slack only exists at coil at room temperature, but most coils experience a temperature rise of 40oC in steady state. The minimum operate voltage therefore climbs at 3900ppm/oC, same as the copper winding.
  8. While technically true (i.e. one *can*), it's safer to switch the hot
    leg or both hot and neutral.
    Did you not just contradict yourself?
  9. Guest

    That is an unnecessary precaution for someone working inside the equipment who, if that reckless, is just as likely to touch the live stuff.

    No, the switch and fuse belong on the hot side.
  10. Guest

    On Sunday, December 22, 2013 1:48:56 PM UTC-5, Jim Thompson wrote:

    Sounds like he's using an AC control relay with most of the current limiting due to the inductive reactance ( as a function of the armature being in or out), that's why it actuates at such a low voltage.
  11. In this case, the relay acts as the "power switch." You agreed that the
    switch should interrupt the hot leg. You contradicted yourself.
  12. Guest

    I understand that but what does that have to do with relay contacts on the hot side? Is it a NEMA, NEC or UL requirement? If not, it's a non-issue.
  13. Guest

    I know enough to know that relays are not used that way without a manual disconnect. If you can't cite a regulatory requirement, there is no discussion here.
  14. My reply to you has nothing to do with regulatory requirements. You
    stated that one can switch either hot or neutral leg, then in the same
    post, you agreed that the hot leg should be switched. Regardless of any
    regulatory requirements, you contradicted yourself.
  15. Guest

    Don Y's words were "Ditto with fuse placement, "power switch", etc. " No one refers to relay contacts as "power switch." Power switch means that gizmoid with ON/OFF labels that you work manually. Looks like it's remedial reading time for you.
  16. Nice try, Fred.
  17. Guest

  18. Guest

    You don't much about relays, you don't know anything about compliance, all you're here to do is promulgate a bunch of anecdotal mythology.
  19. I am not the only one posting to this thread who disagrees with you. I
    notice that recently you have been ridiculed by others in different
    threads within this newsgroup. Have you considered the possibility that
    there may be a common denominator?
  20. Guest

    Science and engineering are not a democracy. You're a pathetic little idiotnothing of a person to fall back on that puny non-justification, and you're too dumb to realize just how idiotic you look to anyone with a working knowledge of the technology. Imbeciles like you make the internet the trash heap of misinformation, ignorance and mediocrity it is today. The bottom line is you don't know what you're talking about. STFU and go away.
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