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Consequences of having P1000 VFD fed from a motor starter instead of a breaker.

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    #16
    Originally posted by Jraef View Post
    Ok true. The drive doesn't care if power comes from a breaker or a contactor.

    But a contactor implies a control circuit and that generally means it is going to be cycled on and off more than if it were just a breaker or fused switch. So the risk is not the device itself (other than a possible code violation), the risk is in allowing operators to cycle power too easily which generally results in too much. I just investigated a drive failure where they used a contactor that was INTENDED to be for E-Stop only. But the lazy operators slapped the E-Stop button every time they stopped the machine rather than hit the normal Stop button, resulting in the drive being power cycled 20 times per day. The only reason they used the E-Stop was because it was 6" closer to them than the normal Stop button ...
    If you are doing a retrofit you ensure that the operator controls are linked to the drive, not the starter.
    Of course you have to consider the interface. That's just control system design.
    Si hoc legere scis nimium eruditionis habes.

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      #17
      Originally posted by Jraef View Post
      But the lazy operators slapped the E-Stop button every time they stopped the machine rather than hit the normal Stop button, resulting in the drive being power cycled 20 times per day. The only reason they used the E-Stop was because it was 6" closer to them than the normal Stop button ...
      Good argument for e-stops than can't be reset by the operator.

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        #18
        FWIW, the instruction manual says to refrain from switching the drive On and off more than once every 30 minutes.
        Tom
        TBLO

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          #19
          Originally posted by ptonsparky View Post
          FWIW, the instruction manual says to refrain from switching the drive On and off more than once every 30 minutes.
          During normal operation you shouldn't have to but it would a bit of a contraint during commissioning.
          Si hoc legere scis nimium eruditionis habes.

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            #20
            Originally posted by Besoeker View Post
            During normal operation you shouldn't have to but it would a bit of a contraint during commissioning.
            Gasp! Are you saying that it takes more than one try? My image has been destroyed.
            Tom
            TBLO

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              #21
              Originally posted by ptonsparky View Post
              Gasp! Are you saying that it takes more than one try? My image has been destroyed.
              We can work on that.........

              What if you have to check the motor rotation before coupling to the load..................
              Ever so slightly more seriously, and I can be from time to time, it's usually to check the correct operation of external controls and indication. Field wiring if you like.
              Si hoc legere scis nimium eruditionis habes.

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                #22
                I thought that all VFDs required short circuit protection? I had a UL shop sometimes use a motor protector (MP) instead of a 3-pole circuit breaker to save cost, but the motor protector sometimes tripped too easily and had to be replaced with a regular breaker. Since then, on new equipment, I requested to not use a MP. I have had several existing pumps (typically 1 to ~20HP), and then add a VFD to the system that had an existing motor starter and MP (two separate devices) and then use a contact from the motor starer to start the VFD. Again, if the motor protector tripped easily (rarely happened though), then it was replaced with a 3P breaker.

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                  #23
                  Originally posted by FountainGuy View Post
                  I thought that all VFDs required short circuit protection? I had a UL shop sometimes use a motor protector (MP) instead of a 3-pole circuit breaker to save cost, but the motor protector sometimes tripped too easily and had to be replaced with a regular breaker. Since then, on new equipment, I requested to not use a MP. I have had several existing pumps (typically 1 to ~20HP), and then add a VFD to the system that had an existing motor starter and MP (two separate devices) and then use a contact from the motor starer to start the VFD. Again, if the motor protector tripped easily (rarely happened though), then it was replaced with a 3P breaker.
                  Depends on what you means by "Motor Protector". If by that you mean a "Motor Circuit Protector", which is a Westinghouse trade name for a Instantaneous Trip (Magnetic-Only) circuit breaker, then technically, you cannot legally use those in this application no matter what. They are ONLY allowed in a combination motor starter, which can only be used as a motor controller, not a feeder.
                  __________________________________________________ ____________________________
                  Many people are shocked when they discover I am not a good electrician...

                  I'm in California, ergo I am still stuck on the 2014 NEC... We'll get around to the 2017 code in around 2021.

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