Disconnect Switches

This topic contains 4 replies, has 2 voices, and was last updated by  Kraig Stinnett 5 months, 3 weeks ago.

  • Author
    Posts
  • #9252

    Kraig Stinnett
    Participant

    Can disconnect switches be used on the output of a VFD?


  • #9253
    John C
    John C
    Galco Representative

    Hello Kraig, we do NOT recommend using a Disconnect Switch on the output of a VFD because it can cause damage to the output section of it if opened or closed while drive is in operation. We recommend using disconnect switches or contactors on the input power to the drive rather than the output. This way the drive will not be damaged from operation of the switching device used. If it is absolutely necessary to do so in your application then an auxilary contact must be mounted to the switch that will Break before the main contacts do when opening, and Make after the main contacts do when closing. Make sense?


  • #9254

    Kraig Stinnett
    Participant

    OK then, but if I have to use this where do I connect it into the drive?


  • #9255
    John C
    John C
    Galco Representative

    If you have to use this configuration, then the auxilary contact will need to connect into either an STO (Safe Torque Off) input or the Enable input. The idea here is to get the drive to shut off the output immediately when this contact breaks for any reason. If this auxilary contact is defeated or jumped out and the drive is started with output power and no motor connected, then the motor gets connected with the drive already in operation, we can almost guarantee the drive will fail instantly, hopefully it will just fault out, but that is asking a lot of the fault response of the drive, understood?


  • #9256

    Kraig Stinnett
    Participant

    Yes thank you John


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