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  • Distance restrictions

    I wish to control vent fans in our new warehouse - this is what I would like to do, can someone tell me if this will work or not?

    The warehouse is 10,000 square feet 50' wide, 200' long. I am using 1 hp motors to drive 48" fans 100' apart, the system will operate on 480 volts. I want to have the two GS2-41P0 drives in a common cabinet midpoint, running the wiring in 1/2" EMT, then 3/8" greenfield to the motors, for a total run of about 60' each.

    Then I want to control the system using a Click PLC in the same cabinet, operator interface to be a C-More Micro non-Touch EA1-S3ML-N mounted approximately 150' to 175' away.

    I can work out the rest of the details. The motors will usually be running at full speed or nearly so, although I want to be able to control their speed if necessary (thus the GS2 drives and the PLC).

    Does anyone see a problem with the wiring lengths involved? At least I am in the planning stages although I've already purchased the GS2-41P0 drives and MTR-001-3BD18 motors - these motors will be running "air over" so cooling won't be an issue at any speed.

    Thanks in advance!


  • #2
    Check the manuals for the VFDs and see at what motor wire length limit they recomend line reactors. I think you're close at 60'.

    I'm more concerned about the communication link to the HMI. I believe you'll need to be using RS485 on that long of a run. Again, check the manual to be sure.
    Bob

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    • #3
      DetroitSound

      Allen Bradley has published a PDF that lists different motor lead lengths with several of their VFD's and different motors. The PDF is available at https://www.google.com/url?sa=t&rct=...04317490,d.cGU

      The data begins on page 84 table 15. We can presume the drive you have chosen is equal to the PF4 and the motor you have chosen is equal to a 1000 volt or 1200 volt motor. Note the inverter duty motor http://www.automationdirect.com/adc/...o_10HP%29/Y364 would be equal to the 1488 volt motor in the chart.
      PERCUSSIVE MAINTENANCE: The fine art of whacking the devil out of an electronic device to get it to work again.

      Vaughn

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      • #4
        Originally posted by Bob S BN View Post
        Check the manuals for the VFDs and see at what motor wire length limit they recomend line reactors. I think you're close at 60'.

        I'm more concerned about the communication link to the HMI. I believe you'll need to be using RS485 on that long of a run. Again, check the manual to be sure.
        I'm thinking that I probably should bring 5 volts for the HMI separately, I see serious voltage drop trying to get the 5 volts from the Click.

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        • #5
          5 volts for the HMI running that distance isn't going to cut it. Nor will RS-232. The signal will be so degraded that the PLC will never decode it.

          You are going to need a EA-MG-SP1 and probably a EA-COMCON-3A to make the RS-485 conversion easy.
          If you have an urgent issue, please contact AutomationDirect's Technical Support team.

          AutomationDirect.com Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support

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          • #6
            While you can sometimes have success with very long runs on RS232 (using low capacitance cable with a true standard RS232 signal), you're better off just going RS485 over twisted pair.Just use a good quality cable and don't forget your terminators.

            http://www.automationdirect.com/adc/...%29/L19827-500

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            • #7
              Originally posted by DetroitSound View Post
              I'm thinking that I probably should bring 5 volts for the HMI separately, I see serious voltage drop trying to get the 5 volts from the Click.
              And the GS2 drive manual says over 75' a reactor should be used, I'm going to try it without. I'm looking forward to being able to give it a long (15 second or so) accel time...

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              • #8
                From experience.. Put reactors in now..

                'We'll see if it runs'.. ends up being, "Why are we burning so many motors on the VFD Ventilation Fans?.. they are only lasting a year!"

                Cap

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                • #9
                  I agree put the reactor in now. It lowers the reflective wave (high voltage spike) on long wire runs that will damage the windings in the motor over time.

                  JW

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                  • #10
                    Originally posted by jwbaker3 View Post
                    I agree put the reactor in now. It lowers the reflective wave (high voltage spike) on long wire runs that will damage the windings in the motor over time.

                    JW
                    *THAT* is what I was wondering about. It needs to be near the drive, correct? (as opposed to near the motor) If I mount the drives centrally, as opposed to near the motors, I will certainly do that.

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                    • #11
                      Originally posted by Do-more PE View Post
                      5 volts for the HMI running that distance isn't going to cut it. Nor will RS-232. The signal will be so degraded that the PLC will never decode it.

                      You are going to need a EA-MG-SP1 and probably a EA-COMCON-3A to make the RS-485 conversion easy.
                      OK, I am a bit confused with RS-485, but I'm sure we can figure this out. I've never really worked with RS/TIA/EIA-485 before, so these are newbie questions.

                      Note that the Click has three terminals for RS-485. They are marked +, - and LG. I'm assuming that the LG terminal is for the ground wire on the cable and that the Click is half duplex?

                      Click image for larger version

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                      Now the EA-COMCON-3A has RD +/- and SD +/-. I assume that is full duplex.

                      Click image for larger version

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                      What is the proper way to interconnect these? RD+ and SD+ together and to + on the Click and RD- and SD- together and to - on the Click?

                      Also, there has also been mention of a terminator. If I use the recommended wire that should be a 120 ohm resistor on both ends of the cable, correct?

                      Does either the EA-COMCON-3A or the Click have an internal bias network, or does that have to be added too? Is one needed?

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                      • #12
                        Closer to the motor the better.

                        JW

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                        • #13
                          Check out the C-more micro software help file. It has all of the wiring schematics in it under the PLC protocol that you will be using.
                          If you have an urgent issue, please contact AutomationDirect's Technical Support team.

                          AutomationDirect.com Technical Support: 1(800) 633-0405 or (770) 844-4200 Email Tech Support

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                          • #14
                            Originally posted by jwbaker3 View Post
                            Closer to the motor the better.

                            JW
                            At the motor end I will have to )transition from EMT (long run to the drive) to Greenfield or Sealtight (short run to the motor) so putting a reactor in a pull box there would be relatively simple.


                            Now I have the reactors, and in the Automation Direct Three-Phase Reactor Installation Guide, it says, in part:

                            OUTPUT

                            When installing the Reactors on the OUTPUT side of the Variable Frequency Drive (VFD), please use the following guidelines:

                            Reactors should be mounted as close to the output terminals of the VFD as possible.

                            Change in plans...
                            Last edited by DetroitSound; 11-13-2015, 08:55 AM. Reason: New information

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                            • #15
                              Two other questions

                              I am planning on using a Click to control the drives. It will be fairly simple, I want to have a start / stop (DI1) and low-medium-high speed (DI...whatever)

                              1) can the source / sink outputs of a Click operate this directly?

                              2) I'd like to use a C0-08TD1 or C0-08TD2 output module, outputs 1-4 for drive 1 and outputs 5-8 for drive 2. As long as I keep C1 / C2 or V1 / V2 with the appropriate drive, is there any problem with this?

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