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  • Need VFD advise

    While using the mill for the first time, it became evident that a reversing switch is sorely needed. Since a decent one is priced only slightly less than the VFD below, my thinking is that I should install the original 3 phase motor and go with the VFD. Since I don't know squat about a VFD, my questions are, will the VFD provide a reverse rotation function, and is it powerful enough to handle the 2 HP motor? Also will there be a downside to doing this, or should I stick with the 1PH motor and get a reversing switch? Any help will be appreciated.
    Dave C


    VFD: https://www.ebay.com/itm/3-0KW-220V-...D/202694510173
    “I know lots of people who are educated far beyond their intelligence”

    Lewis Grizzard

  • #2
    Read this article that I wrote on the subject. All your questions answered.

    http://www.oursplitrock.com/mill-4.pdf

    And yes, 3 phase and a VFD IS the way to go, the only way!!
    Peter
    Grantham, New Hampshire

    Comment


    • #3
      Short story:

      VFDs provide reverse, yes.

      THAT VFD is spec'd for enough HP to more than power a 2 HP motor. (but see below)

      The only downside is if the mill has multiple belt positions for speed selection, but that you decide to try to cover all speeds with the VFD as "the" speed control. You usually are better off keeping the pulley system, and back gear type speed range changer (if any). The VFD cannot give you the power needed to swing big cutters at low speed if you try to get that speed by turning down the VFD speed control. Large cutters may just stall the motor if you try to do that.

      Details about "that" VFD..... It looks a lot like the infamous "Huanyang" VFDs, which have been all over the place on reliability and even performance. Some folks never have a problem, some have had problems right out of the box, or within a pretty short time. I would suggest that the low cost may be telling you something. A TECO or Hitachi VFD will be a much better bet as far as being a good reliable unit.

      Your mileage may vary, some settlement may occur, etc, etc.
      1601

      Keep eye on ball.
      Hashim Khan

      Comment


      • #4
        Just about all VFD's have a PLC on them, i.e. low voltage I/O for control and status output/control.
        One feature is if you are in FWD run at high rpm and switch to the REV while doing so, the motor will decelerate at the programmed rate, before accelerating up to REV.
        Max.

        Comment


        • #5
          I like Automation Direct. Not the cheapest, but good support in USA, reliable units, easy to program. The remote control costs less than $20 to build and lets you put the controls where you want to. On my table saw the remote control is on a magnet and a 10 foot cable. Allows me to get long boards in position before I start the saw and when I want to cut short things,it sits right under my left hand read yo hit the kill switch.
          Peter
          Grantham, New Hampshire

          Comment


          • #6
            Automation Direct also sell WEG, which are a excellent line I have worked with.
            BTW to the OP ensure you get a Vector capable control not Voltage/frequency version for your application.
            Max.

            Comment


            • #7
              Originally posted by MaxHeadRoom View Post
              BTW to the OP ensure you get a Vector capable control not Voltage/frequency version for your application.
              Max.
              Max, does the line "Torque Control:Torque increase settable by max. 10.0%. The starting torque can reach 150% at 1.0Hz." indicate vector control?


              Dan
              At the end of the project, there is a profound difference between spare parts and extra parts.

              Comment


              • #8
                Originally posted by danlb View Post
                Max, does the line "Torque Control:Torque increase settable by max. 10.0%. The starting torque can reach 150% at 1.0Hz." indicate vector control?


                Dan
                Not Max, but..... That may indicate the availability of a low speed boost feature that is not vector. It is really just a modification of the V/Hz "law" at low speed, giving more V than the normal V/Hz would call for. It tends to give a better very low speed response, but is not a cure for the problem of low torque compared to a mechanical reduction. (For that matter, vector control does not do so much for that issue either)

                The feature is reasonably common on VFDs intended for the HVAC market. (You likely do not want an HVAC type, they often lack many settings which are available on general purpose VFDs)
                1601

                Keep eye on ball.
                Hashim Khan

                Comment


                • #9
                  Originally posted by Dave C View Post
                  While using the mill for the first time, it became evident that a reversing switch is sorely needed. Since a decent one is priced only slightly less than the VFD below, my thinking is that I should install the original 3 phase motor and go with the VFD. Since I don't know squat about a VFD, my questions are, will the VFD provide a reverse rotation function, and is it powerful enough to handle the 2 HP motor? Also will there be a downside to doing this, or should I stick with the 1PH motor and get a reversing switch? Any help will be appreciated.
                  Dave C


                  VFD: https://www.ebay.com/itm/3-0KW-220V-...D/202694510173
                  i have to commend their ingenuity.. putting holes through the heat sink to cool off the capacitors

                  Comment


                  • #10
                    Originally posted by danlb View Post
                    Max, does the line "Torque Control:Torque increase settable by max. 10.0%. The starting torque can reach 150% at 1.0Hz." indicate vector control?


                    Dan
                    Yes typically starting torque can be 150% - 200% of rated torque at close to zero Hz.
                    https://www.machinedesign.com/motors...ol-method-vfds
                    Max.

                    Comment


                    • #11
                      Go by current rating, not HP rating. A 3hp VFD is 2.2kw, 10.6 amps.
                      One complaint about my Teco CV7300 that I blew up, the jog function will not work if it's not in run. The new VFD I have that is billed as the TECO CV7300 replacement calls the jog function jog/run. Works as I would like.
                      Try to get a Vector drive VFD. Gives you more torque at lower speeds. Still want the backgear though in case you want to use a 5" holesaw on something.

                      Sent from my SM-G950U1 using Tapatalk

                      Comment


                      • #12
                        Thanks all for your help. My questions have been answered, and it appears that I need to look elsewhere for a more reliable unit. I did like the price though
                        “I know lots of people who are educated far beyond their intelligence”

                        Lewis Grizzard

                        Comment


                        • #13
                          Originally posted by Dave C View Post
                          Thanks all for your help. My questions have been answered, and it appears that I need to look elsewhere for a more reliable unit. I did like the price though
                          Read the manuals to the ones you look at. Expect to pay 200 to 350 for a decent one.

                          Sent from my SM-G950U1 using Tapatalk

                          Comment


                          • #14
                            There is one now on E**Y that is just what you are looking for.
                            https://www.ebay.com/itm/Automation-...IAAOSwMoldCrJU
                            Grantham, New Hampshire

                            Comment


                            • #15
                              Originally posted by CPeter View Post
                              There is one now on E**Y that is just what you are looking for.
                              https://www.ebay.com/itm/Automation-...IAAOSwMoldCrJU

                              thanks, but I'm not too keen on buying a used one.
                              “I know lots of people who are educated far beyond their intelligence”

                              Lewis Grizzard

                              Comment

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