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  • schematic help please

    I am wiring ac drive up. The schematic shows this.



    Do the stop and forward switch look like momentary switches? If so great.If not I need new switches.Thanks Jim

  • #2
    Hi Jim,

    The schematic is not very clear on this, but the description of the functions imply that the direction switch is NOT momentary. The run and stop switches appear to be momentary. There is probably a way to program the inputs to allow momentary switches to do what you want. For example, 3 momentary switches, 1 normally closed for STOP and 1 normally open for FORWARD and 1 normally open for REVERSE.

    What VFD do you have (make and model)? I would be happy to look at a manual and point you to the right pages.

    Robin
    Robin

    Happily working on my second million Gave up on the first

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    • #3
      If I read it correctly, my take is that none of the switches should be momentary.
      The run switch shows NO (normaly open) and operates with the switch closed.
      The stop switch shows NC (normally closed) and stops when opened.
      On the direction switch, It shows forward with the switch opened, and reverse with the switch closed.

      Others will correct me if I'm wrong.

      bones

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      • #4
        It is an Omron 3G3MV. Thanks Robin.

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        • #5
          Clear as mud,the stop switch is a momentary with NC contacts like any other stop/start button.

          The direction switch could be a maintained contact switch like a rotary or toggle.Pick the direction you want,then start?

          Seems like it would be a PITA to use if both were momentary.

          What does the previous page say or show?
          I just need one more tool,just one!

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          • #6
            Maybe my understanding of a momentary switch is wrong, but I wouldnt want something that returned to its normal position when released for a stop switch.

            bones

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            • #7
              What I have is a 2 position switch.Both N.O. This would give me my directions. As you rotate the switch further there is a momentary switch on both sides. This would give me the start that I need.Then all need is a NC switch for stop. I have this also.

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              • #8
                First, this is not a schematic. Schematic diagrams are designed to show how the circuit works and this diagram clearly does NOT do that. It is a wiring diagram only.

                That being said, as others have stated, it is not completely clear weather the start and stop switches are momentary or not. However, I would infer that the "NO" and "NC" designatons do suggest that these switches are momentary. These designations are normally only used for momentary switches. Also, it makes no sense to use two separate switches (the diagram does not show any linkage between the start and stop switches) that are not momentary. If they are not momentary, then either one could be used to turn the machine both on and off. And to operate with non-momentary switches would require the operator to turn them both on and off for each run/stop cycle. I would thefore would put the chances of them being momentary at least at 99%.

                On the other hand, the forward/reverse switch which is NOT labeled with "NO" or "NC", would almost have to be non-momentary.
                Paul A.

                Make it fit.
                You can't win and there is a penalty for trying!

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                • #9
                  Originally posted by Bones
                  Maybe my understanding of a momentary switch is wrong, but I wouldnt want something that returned to its normal position when released for a stop switch.

                  bones
                  Momentary switches are quite common for all functions when either electronic or relay logic control circuits are employed.
                  Paul A.

                  Make it fit.
                  You can't win and there is a penalty for trying!

                  Comment


                  • #10
                    Originally posted by j king
                    What I have is a 2 position switch.Both N.O. This would give me my directions. As you rotate the switch further there is a momentary switch on both sides. This would give me the start that I need.Then all need is a NC switch for stop. I have this also.
                    I'm not quite sure what kind of switch you are describing with, "What I have is a 2 position switch.Both N.O. This would give me my directions. As you rotate the switch further there is a momentary switch on both sides. This would give me the start that I need."

                    This sounds like it is a lot more than what is needed for the Start switch. A simple, NO (normally open) push button should be best.
                    Paul A.

                    Make it fit.
                    You can't win and there is a penalty for trying!

                    Comment


                    • #11
                      I second Paul's thoughts. Only momentary switches have NO or NC designations. That is also how a standard push-button ON-OFF switch operates.

                      Don Young
                      Don Young

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                      • #12
                        Paul. That is what the direction switch looks like to me too. This is why I am hoping that the other 2 are momentary switches...

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                        • #13
                          Not Momentary

                          From what I read, momentary switches are not used.

                          S3 states: Forward/Reverse rotation command. (Forward with the Direction switch opened, Reverse with the Direction switch closed.)

                          My VFD's also need solid switches, not momentary. I can reverse on the fly, by changing one switch.

                          But, I agree, that's not a concise diagram.

                          Comment


                          • #14
                            Jim,

                            I read and read and read again the manual for this drive and I am still not sure I understand it completely . The switches appear to be maintained action only, no momentary allowed . Now on to actually setting it up the way you want.... You need to decide how you want to control start/stop and forward/reverse. IE: one switch for all or 2 switches, 1 for direction and 1 for start/stop. The easiest thing to try is to hook up the main power wiring and the motor connections then play with the control programming and switch functions with clip cords. This way you can keep the speed set slow for safety and see what happens when you do various things. As I read it you can not actually damage anything as long as the machine is clear and the speed set low. The worst that can happen is it might throw a fault and stop like it is supposed to.

                            Robin

                            PS: This thing has a very poor users manual
                            Robin

                            Happily working on my second million Gave up on the first

                            Comment


                            • #15
                              The partial schematic uses the wrong symbols. They do not agree with the written description of each function as someone has mentioned. I believe both my Hitachi and Teco VFDs are the same, no momentary switches. Den

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