what is this schematic symbol

Discussion in 'General Electronics Chat' started by dalerp, Oct 20, 2009.

  1. dalerp

    Thread Starter New Member

    Oct 20, 2009
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    I am looking at a crane control system and see an unknown to me symbol. It looks like a pair (two sets) of contacts of a relay in series. On one of the parallel lines making each set of contacts there is a triangle shape flag flying



    II II a flag on the second I of each pair at the top pointing to the right

    thanks for any and all help
     
    Last edited: Oct 20, 2009
  2. BMorse

    Senior Member

    Sep 26, 2009
    2,675
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    can you post a pic or the schematic??
     
  3. Wendy

    Moderator

    Mar 24, 2008
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    A picture is worth a thousand words. Truer words were never spoken, especially about electronics.
     
  4. dalerp

    Thread Starter New Member

    Oct 20, 2009
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    thanks for help so far
    I added a pdf attachment in the beginning post
    the unknown symbol are the ones that look like relay contacts (ladder logic?) with flags
    thanks
     
  5. ELECTRONERD

    Senior Member

    May 26, 2009
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    Interesting, those look like capacitors but they have a funny mark on one end. Maybe that's to note the polarity of the cap.
     
  6. wr8y

    Active Member

    Sep 16, 2008
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    On the schematic of the RTU's I used to work on (Remote Terminal Unit - Part of a SCADA system) that was the symbol I remember for a relay contact.

    The coil that caused the contact to close was not always right near the "contacts" on the schematic.

    MAYBE, not sure, but MAYBE those are relay contacts.

    Hate to say it, but seeing the WHOLE schematic would help. (Not that I'd be any more sure of my statement - my experience with industrial schematics is very limited.) My work on those RTU'S was 20 years ago!

    Or, maybe ELECTRONERD is right.
     
  7. Wendy

    Moderator

    Mar 24, 2008
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    They definately resemble ladder logic, but I've never seen it quite like that. Still, relay contacts would be my first guess. I haven't seen anything like it before.
     
  8. ELECTRONERD

    Senior Member

    May 26, 2009
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    dalerp,

    Take a multimeter and set the selection on capacitance. See if there is a notable quantity of capacitance and then you can verify whether they are caps or not.
     
  9. dalerp

    Thread Starter New Member

    Oct 20, 2009
    4
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    M1 is the Drive Enable Contactor
    these maybe aux. contacts on M1???
    these contacts? go to partially enable the power to release the brake.

    I just wonder why they are double?
    and what the flags mean.

    Thanks to all for all the help
     
  10. Duane P Wetick

    Active Member

    Apr 23, 2009
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    Probably the part of the contactor that moves.
     
  11. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    If they are relay contacts, putting them is series may be a safety measure in case one hangs up or gets welded closed. We do that on our high-power winch contactors. We also put an LED across them, so you know if one has hung up.

    John
     
  12. dalerp

    Thread Starter New Member

    Oct 20, 2009
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    Thanks for everyones help

    I came across a standard symbols table here at work and found the symbol

    it is a contact with magnetic blowout. (20 amps and over)

    Thanks again
     
  13. Wendy

    Moderator

    Mar 24, 2008
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    Thanks for the feedback. It is even more appriciated because of its rarity.
     
  14. aq_rules

    Member

    Oct 28, 2009
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    I Guess a DPDT RELAY.....
     
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