What do the following triangles mean in the given schematic?

Discussion in 'General Electronics Chat' started by Wael92, Jul 6, 2016.

  1. Wael92

    Thread Starter New Member

    Jul 6, 2016
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    What do the following triangles in the schematic represent?
     
  2. MaxHeadRoom

    Expert

    Jul 18, 2013
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    They mean the power Common plane.
    Max.
     
    Wael92 likes this.
  3. Wael92

    Thread Starter New Member

    Jul 6, 2016
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    Thanks Max,
    What exactly does that mean though?
     
  4. Papabravo

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    Feb 24, 2006
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    I think they are differential digital inputs. One input sets the logic threshold (A2) and the other input is either HIGH or LOW with respect to that threshold.
     
  5. MaxHeadRoom

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    The power negative is generally used as the circuit common plane which is usually symbolized by the inverted triangle symbol, in some cases this can be connected to earth ground and the appropriate symbol is shown for this.
    As per the PDF.
    In N.A. the earth symbol is often misused as power common when it is actually not at earth ground. Also in N.A. ground is also used to indicate an earth conductor which further confuses the issue.
    Max.
     
  6. KeepItSimpleStupid

    Well-Known Member

    Mar 4, 2014
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    In stat schematic, the start switch would short the power if A1&A2 are power, so obviously they could be something else.

    Commons usually have one wire to them instead of two.
     
  7. MaxHeadRoom

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    Actually taking another look it appears to be a PLC input module which is usually an opto input type, which would make the symbol in this case the two inputs of a Opto IC.:oops:
    Max.
     
  8. MaxHeadRoom

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    I assume by the IEC symbols you are not in N.A.?
    If this is a PLC input, they just show the symbol as a representation of the input, you do not require to know the details.
    Max.
     
  9. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    No, the far left shows a relay coil. So start (a momentary push button) energizes that relay. Stop breaks the circuit and allows the relay to release.

    upload_2016-7-6_10-48-24.png

    If that is correct, then the triangles are probably a power common, e.g., screw terminals on a bus bar.

    John
     
  10. MaxHeadRoom

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    If the OP confirms it is a PLC input then the opto representation makes perfect sense.
    But the E-stop P.B. and output 04 N.C. contact actually confirms the power in.
    If they were GND symbols the E-stop & 04 contact would short the power.
    Input I.4 is a confirmation input.
    Max.
     
  11. KeepItSimpleStupid

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    The ting under A1 could be a thermal breaker although an AC coil is probable too.
     
  12. MaxHeadRoom

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    A1 is the symbol for a fuse/breaker usually.
    Found the manual for it and it is a TeSys LTM R unit which is a form of PLC if anyone cares to search.
    A1 A2 are the power input, AC or DC.
    The unit is a multi drop unit from a Modbus fed system, specifically for 3 phase motor monitoring.
    Max.
     
    Last edited: Jul 6, 2016
  13. jpanhalt

    AAC Fanatic!

    Jan 18, 2008
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    A rectangle with diagonal line is common for the coil of a relay. Maybe that is a European/German practice?

    upload_2016-7-6_13-59-41.png

    Sources:

    http://www.electrical-installation.org/enwiki/Elementary_switching_devices
    http://electronics.stackexchange.com/questions/240280/symbol-or-marking-on-safety-relay

    The squiggle is not so common, but neither is that combination for a fuse. I assume that the squiggle meant an AC coil. With the START and STOP buttons, a relay makes sense. Can you show any examples of fuses that match that symbol?

    John
     
  14. MaxHeadRoom

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    Those are common IEC symbols, looking at the manual, it also appears to be used to indicate either AC or DC input, which the unit is according to the manual, in this case it seems a loose use of the symbol.
    It is a amalgam of the symbols used on a AC/DC power source that can be either AC or DC.
    The circuit is from the power through the output relay contact trough the E-stop P.B., both OR'd to an input, IOW an input monitoring the E-stop String, .
    This apparently is not a common variable use PLC, but a Motor monitor specialized one.
    The manual also states that the input block is just a symbolic representation of the inputs.
    Max.
     
  15. MaxHeadRoom

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    Page from the manual.
    Max.
     
  16. hp1729

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    They are voltage comparators. They compare the inputs to a reference level on A2.
     
  17. MaxHeadRoom

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    Did you very this as a fact?
    Most of the PLC's I use are opto's input and can be configured either sink or source.
    See the bottom of page 30-2.
    Max.
     
  18. ian field

    Distinguished Member

    Oct 27, 2012
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    They don't conform to that standard.

    Once I worked for a company who's drawing office only knew mechanical engineering symbols......................................
     
  19. MaxHeadRoom

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    o_OI corrected myself in post #7??
    Inverted triangle is the Logic common symbol.
    Max.
     
  20. KL7AJ

    AAC Fanatic!

    Nov 4, 2008
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    Either op amps or comparators.
     
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