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  • (gloat?) Have VFD! now what?

    Did a friend a favor (really, I didn't want anything) but he found it
    fit to give me a great condition inverter (VFD)

    its a Mitsubishi FR-E740-095-EC 3 phase 3.7kW

    looks awesome.

    my first reaction was .. wow.. and I thought "that'll be great on
    my belt sander"

    Now I'm wondering if it might not be a waste there.

    I run all manual machines.. and am wondering what the best bang for
    buck might be for the VFD.

    Worth putting it on the bridgeport?
    Or maybe the lathe? (My top speed is currently 1200rpm I think.. maybe
    I could run it faster? and melt the headstock)

    Thoughts?

    feel like a kid at christmas.

    Can I run more than one machine off of it? Meaning I put it right after
    the break box and have AC control for everything on that circuit? (only
    one machine at a time of course) -- or are these VFD programmed for
    a specific motor config?


    Tony

  • #2
    In case you did not already know, VFD's only work on 3 phase motors.

    Comment


    • #3
      Normally you can use one configuration for more than one motor as long as the motors are fairly close, name plate info wise.
      However you have to interlock the change over relay or contactors so that the switching does not take place when one is running.
      IOW the VFD has to be in Stop.
      Mitsubishi VFD's are nice units, I have used a few of them.
      A Generally rule for non-vector rated motors is that if they are 4 pole, you can run them up to 120Hz.
      For maximum efficiency you would tune the parameters for a particular motor, and also Mitsubishi have an auto-tune feature which gets you in the Ball-park.
      Max.

      Comment


      • #4
        My sentiment is a lathe (with no back gear) is usually the best application for a VFD. Nice low speed for threading up to a shoulder, instantly variable speed for keeping that facing cut at that sweet spot for a great finish, soft start in case you may have set something (i.e.: compound) to foul your chuck and fast stop to immediately respond to safety issues all make the VFD a winner in that application.

        Again, as mentioned in an earlier post, this is conjunction with a 3 phase motor.
        Last edited by Pherdie; 03-31-2012, 05:22 PM.

        Comment


        • #5
          From the datasheet

          http://www.999inverters.com/media/do...Cdatasheet.pdf

          this version - the 740 - needs 3 phase input as well. It's the 720 series that bumps 1 phase up to 3 phase.

          If you're already running 3 phase motors on 3 phase power, this will let you vary the speed of your machines. If you are running 1 phase machines on 1 phase pwoer, this is a boat anchor. If you are running 3 phase machines on a rotary or other converter from 1 phase power, it is possible that you could use this on three phase input to vary your speeds.

          Most manufacturers, Hitachi for example, produce two ranges for different inputs. Commercial users mainly go for the 3 phase inputs machines.
          Richard - SW London, UK, EU.

          Comment


          • #6
            Well if you only have single phase machines right now you have a great excuse to go out and spend $1,500- Oh I don't know, Maybe $50,000 on a machine to fit that VFD. So it was a great score. Hell if I got a free VFD I'd go find a machine that fits it. It's a win/win situation.

            Pete

            Comment


            • #7
              A person can always wire strings of multicolored lamps to it and attach the freq control to a stereo. You should get quite a light show from that.

              Comment


              • #8
                Sorry if I neglected to mention: yes I have 3 phase power and 3 phase
                machines..
                bridgeport mill
                colchester lathe
                OMES shaper
                DIY belt grinder
                Thomas Cold Saw

                everything else is single phase.

                Comment


                • #9
                  Hi Tony,

                  I'd put it on the Colchester - variable speed on a big lathe is *nice*

                  That 3.7Kw rating is about 5HP, you can adjust the current limit to accommodate a smaller motor if you need to.

                  I got all geeky and ingenious, fitted a pot for the speed control to the Holbrook's cross-slide, so as I wind it in the speed goes up - hey presto, (nearly) constant-surface-speed like the big boys have on their CNC machines and better finish when facing Large Parts, parting off etc.

                  To do it I fitted a 50mm travel 10K *linear* slider pot with a sprung lever arrangement to match the travel of the pot to the last 3" of cross travel (where it matters) with the ends of the track to the wipers of two rotary 5K linear pots, high end of the "high speed" rotary pot to the DC speed control supply +, low end to 0v via a 6.8K resistor, same but upside down for the "low speed" rotary - this lets you set your max and min speeds that the slider pot can operate between. There, said I got geeky, didn't I? There's also a switch which operates a relay (4-pole, 2-pole would do) to switch betwen the cross-slide "remote" and the normal 10k linear variable-speed pot so I can disable the (n)CSS feature... If I can find my scruffy C-o-C drawing I'll post it up later...

                  Dave H. (the other one)
                  Rules are for the obedience of fools, and the guidance of wise men.

                  Holbrook Model C Number 13 lathe, Testa 2U universal mill, bikes and tools

                  Comment


                  • #10
                    Is that a single phase input or three phase input VFD?
                    Location: The Black Forest in Germany

                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

                    Comment


                    • #11
                      Originally posted by Black Forest
                      Is that a single phase input or three phase input VFD?
                      According to the MEAU site, there has to be a S suffix on the E720(S) and in that case there is only two input terminals L1/N as opposed to the 3ph RST terminals?
                      Max.

                      Comment


                      • #12
                        The 3.7kw will most likely be with a 3 phase input. You need to contact the manufacturer for the derated output when fed single phase. Sometimes it's 50%, but I have some that are derated by 80% - a high end 7.5hp vfd that's only rated at 1.5hp when on single phase!

                        Comment


                        • #13
                          Originally posted by lakeside53
                          The 3.7kw will most likely be with a 3 phase input. You need to contact the manufacturer for the derated output when fed single phase. Sometimes it's 50%, but I have some that are derated by 80% - a high end 7.5hp vfd that's only rated at 1.5hp when on single phase!
                          One thing to be aware of with Mitsubishi when running on 1ph however is that 2 of the phases are often assigned to the control voltage feed input, using the wrong two and you have no control voltage.
                          This way the unit uses configuration links that allow the control voltage to stay alive while the main DC supply is off, i.e. standby mode.
                          I suspect that because this model has a distinct difference in input terminals, either two terminals or three, that you need the S model for 1ph.
                          Max.

                          Comment


                          • #14
                            It should be 3ph->3ph.
                            I have 3ph in the shop.

                            Comment


                            • #15
                              Originally posted by Tony
                              its a Mitsubishi FR-E740-095-EC 3 phase 3.7kW

                              my first reaction was .. wow.. and I thought "that'll be great on
                              my belt sander"

                              Now I'm wondering if it might not be a waste there.

                              I run all manual machines.. and am wondering what the best bang for
                              buck might be for the VFD.

                              Worth putting it on the bridgeport?
                              Or maybe the lathe? (My top speed is currently 1200rpm I think.. maybe
                              I could run it faster? and melt the headstock)

                              Thoughts?

                              Can I run more than one machine off of it? Meaning I put it right after
                              the break box and have AC control for everything on that circuit? (only
                              one machine at a time of course) -- or are these VFD programmed for
                              a specific motor config?
                              Tony
                              Mitsubishi makes a nice inverter in my opinion. If a machine has a single 3 phase motor on it, it is common to run the motor up to 90hz (or more with caution) to over speed it. As for hooking up multiple motors to it, the VFD wants a direct connection to the motor to and start and stop it. I have seen setups that the operator switches the motor's triple pole switches and control logic switchs to the individual machine before powering the VFD. It is best to have similar amperage motors and then set the VFD parameters to the largest motor.

                              As to the off topic 1phase input debate, the Mitsubishi rep told me to connect L1 and L2 then jumper from L2 to L3 for the power input. This de-rates my 3.7kw drive from 5hp to 3hp. My drive is Fr-S520E 3.7kw. pic attached of the jumper. The three wires on the left, white is the jumper. 4 years and no problems.

                              sorry, I can't attach a pic and don't have an online account.

                              Comment

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