Announcement

Collapse
No announcement yet.

3 Phase Switch Question

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • 3 Phase Switch Question

    Last week I bought a Beaver Drill Press that came with a 1/2 HP Leland 3 phase motor. I bought a .75 Kw VFD and attempted to connect it to the motor using the existing 3 phase magnetic switch that came with the machine. From 40 to 65 hertz everything functions well, but at low frequency the switch clicks progressively louder and louder as the frequency is decreased and eventually turns off at around 10 hertz. I suspect that the electro magnet doesn't function at low frequencies. However I do not know much about these kinds of switches and whether they actually will work with a VFD.

    I know that I can wire in a 2 pole switch to the 220 input for on/off function but would like to retain the old switch if possible. Pictures of the motor specs, switch with the cover plate off and specs along with a short video attached.

    Any suggestions?





    IMG_1719.MOV
    7.5 MB
    Thanks




    IMG_1719.MOV
    7.5 MB
    Last edited by tool fan; 10-11-2020, 01:24 PM.
  • Thread Continues Below...

  • #2

    Re: 3 Phase Switch Question

    You are being very unkind to your vfd. Use the mag starter to control the vfd not the motor. The coil on the starter is always single phase.

    Comment


    • #3

      Re: 3 Phase Switch Question

      Originally posted by iamtooler View Post
      You are being very unkind to your vfd. Use the mag starter to control the vfd not the motor. The coil on the starter is always single phase.
      Thank you.

      Comment


      • #4

        Re: 3 Phase Switch Question

        Yes, don’t add a disconnect device between the VFD and motor.

        If you want to use the mag starter to start the VFD, isolate a set of contacts on the starter and connect them to the remote contact input on the VFD.

        Make sure you don’t apply any power to remote contacts.

        You’ll have to add a disconnect switch to the drill press as otherwise the VFD will always be on.

        In light of the above I would simply gut the starter and use the push buttons if you’re looking the vintage look......Rod
        Work is the curse of the riding class.

        Comment


        • #5

          Re: 3 Phase Switch Question

          Originally posted by Rod Sheridan View Post
          Yes, don’t add a disconnect device between the VFD and motor.

          If you want to use the mag starter to start the VFD, isolate a set of contacts on the starter and connect them to the remote contact input on the VFD.

          Make sure you don’t apply any power to remote contacts.

          You’ll have to add a disconnect switch to the drill press as otherwise the VFD will always be on.
          In light of the above I would simply gut the starter and use the push buttons if you’re looking the vintage look......Rod
          Yup, I figured that out, but only after I replaced the old switch with an also old 3 pole Square D switch and mounted it between the vfd and the motor. For now I just unplug the machine after using it.

          Comment


          • #6

            Re: 3 Phase Switch Question

            If it’s electrically between the motor and VFD you should remove it.

            The output of the VFD should never be disconnected from the motor with power applied to the VFD.......Regards, Rod
            Work is the curse of the riding class.

            Comment

            • Thread Continues Below...

            • #7

              Re: 3 Phase Switch Question

              I think Rod has already hammered this home. There should be no switchgear between the VFD and motor.

              The chattering of the switchgear is a result of linear voltage/hurts. When you slow down the hurts to 50% you are at you are at 50% voltage. The switchgear electric magnet has a hard time staying engaged. This is where the chattering starts.
              For every action there is an equal and opposite reaction.
              Sir Isaac Newton.

              Comment


              • #8

                Re: 3 Phase Switch Question

                Originally posted by Matt Matt View Post
                I think Rod has already hammered this home. There should be no switchgear between the VFD and motor.

                The chattering of the switchgear is a result of linear voltage/hurts. When you slow down the hurts to 50% you are at you are at 50% voltage. The switchgear electric magnet has a hard time staying engaged. This is where the chattering starts.
                Thank you for the input. I will move the switch to the 220 volt circuit upstream of the vfd.

                Comment

                Working...
                X