Need help with a circuit - again

Discussion in 'General Electronics Chat' started by ChandlerW, Sep 30, 2012.

  1. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    Hi all,
    I have this project that I need help with. I had a thread on this project but its more than 553 days old and I can’t reply to it.

    I’ve made a new drawing of the physical layout of the circuits. I’ve only documented what works correctly.

    The problem has been, and still is, the solenoids that operate the hydraulic arm do not engage when the switches that operate them are pressed. There is a switch/relay combination that engages the solenoids.

    The saw motor switch/relay combination works.
    The hydraulic motor switch/relay combination works.

    The hydraulic solenoid switch/relay combination is a little more complicated. Only one relay can be engaged at a time. There are also upper and lower limit switches in the circuit.

    If anyone has an idea of how to wire this up please let me know.

    http://forum.allaboutcircuits.com/sh...ad.php?t=50462
     
    Last edited by a moderator: Oct 5, 2012
  2. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    Can anyone tell me why the contactor stays engaged in the attached picture?
    In order to complete the circuit I have to press the Saw Motor On button. Pressing the the button will allow 24V to get to the relay coil.
    When I release the button the contactor/relay? stays engaged.
    Is it because the voltage is now going from the magenta line in the drawing (24V), through the normally closed contacts of the Saw Motor Off button, through the closed contactors on the relay, through the coil, and finally to the 0V circuit to the selenium rectifier?
     
    Last edited: Oct 5, 2012
  3. JoeJester

    AAC Fanatic!

    Apr 26, 2005
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    what is the part number on that relay?
     
  4. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    I don't have it handy but I will find out and post the number tonight.
     
  5. cork_ie

    Member

    Oct 8, 2011
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    I am not that surprised that you haven't got many replies. The drawing is not particularly reader friendly. What is wrong with plain old Black & White?

    If you can let me have the pinouts on the relays I am sure I can help.

    It looks like the ON Button triggers a self latching relay which is held on via the NC contacts of the OFF Button. When the OFF Button is pressed the relay turns off.
     
  6. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    Relay info is Klockner-Moeller DIL 00a 40/59
    I tried to get a picture of it but my camera doesnt have macro.
    I see if I can get a better picture with another camera.

    The drawing was good old black and white. I used a program to export the drawing to pdf and it created all the neat colors that are so hard to read.

    Let me see what I can do with the drawing.
     
  7. cork_ie

    Member

    Oct 8, 2011
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    Ok I have had a look at the previous thread and found a much better clearer drawing.called PehakaSaw.pdf

    What you call Relays are in fact Three Phase contactors with 24Volt DC Coils.

    Can you answer the following questions, referring to the drawing on your previous thread.

    1) Is the switch to the left of the 24V transformer/rectifier the lower limit switch and if so is the bottom contact an NC contact?

    2) Can you tell me what the contact arrangement is on the Emergency OFF switch. i.e NO NC etc.

    3) What is the function of the solenoids? When are they meant to be activated ?
     
  8. paulktreg

    Distinguished Member

    Jun 2, 2008
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    A complete drawing would nice?
     
  9. JoeJester

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    Last edited: Oct 5, 2012
  10. JoeJester

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    Paul,

    I would not want to look at a complete drawing in the color scheme he choose. Now if he went to white background and black lines/components ... that would be good ... as it is higher contrast.
     
  11. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    I would consider that other drawing with some reservation. It was drawn showing how the saw was wired up. Its not very good because the saw doesn't work as it is supposed to.


    A. Yes that is a lower limit switch. Bottom contact is NC

    A. The emergency switch seems to have continuity at all times. I'll need to take some readings and get back with you on it.

    3) What is the function of the solenoids? When are they meant to be activated ?

    A. That is the difficult question. Its a big horizontal saw. When you want the saw arm to raise you would press the button to raise the saw arm.

    When you want the saw arm to lower the operator presses the lower button.
    There are many variables to consider but that would be the basic operation of the solenoids.

    The solenoids are attached to a hydraulic manifold. When neither solenoid is engaged and the hydraulic motor is on, the fluid go through a bypass passage.
    When the raise solenoid is engaged, the hydraulic fluid goes through the passages that direct the hydraulic fluid to extend the hydraulic cylinder.
    When the lower solenoid is engaged the fluid goes through the passages to retract the hydraulic cylinder.
    The arm will stop in its current position when neither solenoid is not engaged. Either solenoid has to be engaged to get movement from the arm.



    I don't have a complete drawing. I was not able to obtain a drawing from the manufacturer or any other source.

    Here's a black and white drawing. There are some changes, just trying to work it out.
     
    Last edited: Oct 5, 2012
  12. JoeJester

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    Apr 26, 2005
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    Emergency shut down switch should be wired in the same line as the stop switch. They both do the same function, interrupt the power on contactor to shut the device down. Each switch will be in series.

    I'll have some questions after I annotate your drawing.

    What other drawing are you talking about? Mine?

    When you depress the Saw On switch, does the contactor close and remain closed?

    Did you troubleshoot the problem to see where the contactor's power was interrupted? How many "emergency stop" switches do you have?

    You need to add some annotations concerning the AC power entering and leaving your power on contactor. I'll redo my diagram to reflect the switches on the 24V vice the ground.
     
    Last edited: Oct 6, 2012
  13. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    I was talking about my other drawing, in the old thread.

    When you depress the Saw On switch, does the contactor close and remain closed?

    Pressing the Saw On switch closes the contactor and it stays closed.

    The Saw Motor On, Saw Motor Off, Hydraulic Motor On, and Hydraulic Motor Off all function properly.

    The contactors all get 24V+ to the coil lead at the lower left of the contactor housing. The other end of the coil gets 0V from the common wire connecting them all along the top of the contactors. This 0V comes from the selenium recetifier.

    The On and Off functions work well but as you can tell, they are pretty straight forward. To release the contactor, the off switch is pressed and the NC path is broken.

    For the solenoids its a different story. There is a pushbutton to engage the contactor but there is no (direct) pushbutton to release the contactor. And this is where the trouble is for me.
    What is it that would cause the contactor to disengage? Hitting the upper limit switch must disengage the contactor for safety reasons.
    But is that the only thing that will do it? That doesn't seem very efficient.
    Turning off the power to the machine would do it.
    Hitting the emergency stop should do it.
    Is the operator supposed to hold the button until it reaches the correct height, then release it? That would make a little more sense to me. The contactor wouldn't need to latch in that case.

    For the lower solenoid its a different operation. You wouldn't expect the operator to hold the button while the saw was cutting. That contactor needs to latch but also needs a way to unlatch. There is no direct switch to disengage the contactor for the lower solenoid either. The lower limit switch would need to disengage the contactor for sure. But there are other conditions that would require stopping the cutting process and lifting the saw arm.
    If an operator were in the middle of cutting and needed to stop cutting and raise the arm, would pressing the Raise button disengage the lower solenoid and engage the Raise solenoid. Seems logical to me.

    The way it is wired up now, pressing the raise or lower buttons do not work. Neither of the contactors close so the solenoids do not engage. I bought it in this condition with the hopes of fixing it.

    This is not my field of study as you can tell. I'm learning daily but there is a learning curve, especially for us adult learners. :)

    Thank you for taking the time to look at the problem I am having.
     
    Last edited: Oct 6, 2012
  14. JoeJester

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    To be honest, those solenoid switched make no sense ... as drawn ...

    It would seem to me the raise button would not be latched as that would cause a single depression to raise the saw till the upper limit swich in the mechanism opens the circuit. I don't know if that's the normal condition or not. If it is, there should be no connections to the lower relay, but a connection to the solenoid.

    The same applies to the lower switch.
     
  15. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    I agree. I just can't work out how to wire it up as the manufacturer intended.
    I guess I'll work on that step. Energizing the contactor by having to keep the pushbutton pressed.
    Do you have any software for testing circuits?
     
    Last edited: Oct 6, 2012
  16. strantor

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    Oct 3, 2010
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    regarding needhelp3.pdf, I have a feeling that some of the places where the lines cross are actually electrical junctions and some are just lines on top of lines. can you please put a dot on the intersections of lines at the places where there is an actual electrical connection?

    also, just to clarify, this is the drawing that you created to depict how the panel is currently physically wired? is it complete? is there more to the system that you haven't disclosed, such as a lumber feeding conveyor that stops while the saw cuts and then an ejector? anything at all like that, even insignificant?
     
  17. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    You are correct. I created the drawing. This is how it is physically wired up. Its how I bought the saw. The previous owner may have done his own wiring. I don't have any history of the saw.
    Ther only junctions are at terminals.
    There isn't any additional components such as a lumber feed or hydraulic clamp.
    There are some limit switches not shown on NeedHelp3. I suppose those would be a big help. They are included in the drawing from the previous thread. I can put them in NeedHelp3.pdf if you think it would help.
     
  18. strantor

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    That would be great. Anything and everything that exists, needs to be in the drawing. small details may seem insignificant, but in reality they may make the difference between 2 completely different functioning circuits.
     
  19. cork_ie

    Member

    Oct 8, 2011
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    OK ,
    From your last post I gather that both the Hydraulic pump on/off and the saw motor on/off are working correctly and I presume wired OK.
    Thus your problem lies with the raise & lower circuit.

    I did some Googleing and have come up with the attached circuit which appears simalar to yours but much clearer and actually makes sense in the operation of the solenoids. They are used to supply hydraulic pressure to raise or lower the saw.

    Can you have a look at it , tell me what part of it you don't understand and I will try and help you.
     
  20. ChandlerW

    Thread Starter Member

    Feb 15, 2011
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    That one is mine too. Proven not to work. Pretty much everything pehaka and schematic or circuit found on the net is probably mine.
    I don't know how I manage to find these obsolete projects but I am not messing with any more after this.
     
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