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New (to me) Lagun FT1 mill need a VFD!!

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  • New (to me) Lagun FT1 mill need a VFD!!

    I just got a Lagun ft1 mill and now i need to get a VFD to run it... Any recommendations? I would like to have the ability to but a E-stop on the VFD (momentary push button). Are there any brands out there that you guys can give me a real-life recommendation on?

    thanks!

  • #2
    Any of the popular brands, Hitachi have a nice line out now, there is a seller on ebay , otherwise WEG and Mitsubishi are good, I would stay away the R.O.C. such as Huanyang for e.g.
    Max.

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    • #3
      Most any will do. It doesn't take much sophistication in a VFD to run a manual machine tool spindle motor. You need but a half dozen parameters. Start-stop, few-rev, accel-decel.and, in yours, an Estop.

      Technically an E-stop disconnects power from the drive motor and applies a brake if there is one. This is not the safest mode for a VFD having regard for personal safety. Disconet the motor and it coasts to a stop. You want to spindle to stop as quickly as possible. If some form of braking or deceleratin is available then that is preferable to a mere coast-down. Therefore the E-stop is better applied to the control string of the VFD than to disconnecr the VFD from line power. The VFD will decellerate the motor responding to its decel parameter.

      Next is the e-stop control unit. It's a simple NO switch, closed when the E-stop is "set" that is rotated and pulled out to "cock it" - which is where it stays for normal machine operation. Actuating the E-stop opens the contacts disconnect control voltage from the VFD inputs. The VFD internal logic treats this as a stop command and decelerates the motor to zero RPM. When the E-stop is depressed (sometimes smashed at in panic) two things happen: the first is the motor is stopped quickly as possible; the second is the motor cannot be re-started until the E-stop is re-set usually by a turn and pull of the push-button.

      Most VFD instructions show you where in the control circuit to connect the E-stop. Most often its in series with the control string.

      Whatever VFD you elect to buy connecting an E-stop is very simple. IF the instructions are clear. If not you may have to do a little research to determine precisely where to connect it but trust me: electrically it's simple.

      FOr example: Look at the link:

      http://www.yaskawa.com/site/dmdrive.nsf/LEG/MNEN-5JLRLE/$File/TM4333GPD333.pdf

      On PDF page 25: read Note 3. Then look on the previous page 24 where note 3 annotates a pair of contacts connected between terminal 3and he control string. "External fault" in this case can be used for an E-stop.

      Clear as mud?
      Last edited by Forrest Addy; 04-27-2012, 02:35 PM.

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      • #4
        Is it possible with most VFD's to have a rapid E-stop deceleration and also a normal deceleration with a normal off or are you typically stuck with one deceleration setting?

        If the latter what would be a good setting balancing the need for an emergency stop with an appropriate deceleration for typical use on a lathe?
        "Patriotism is the last refuge of a scoundrel"

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        • #5
          You can also just use the manual brake.

          Brian
          OPEN EYES, OPEN EARS, OPEN MIND

          THINK HARDER

          BETTER TO HAVE TOOLS YOU DON'T NEED THAN TO NEED TOOLS YOU DON'T HAVE

          MY NAME IS BRIAN AND I AM A TOOLOHOLIC

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          • #6
            The ones I have programmed have a separate setting for E-Stop from the normal deceleration setting. So for the E-Stop you can choose to have the drive cut power entirely to the motor OR rapidly decelerate. There are arguments both for and against each one. The folks that don't like the deceleration generally argue that it is a poor idea to have power running to the motor at all once you hit the E-Stop. Under rapid deceleration, the drive is still sending power to the motor in a controlled fashion. The camp that says have the E-Stop cut power entirely argue that whatever is happening that is causing an "emergency" will likely stop the motor faster than the drive. If the parameter was set for rapid deceleration, it leaves the possibility that the motor actually stops slower since it receives power for the amount of time set for deceleration.

            I can see points to either side of the argument. Take you pick Either one can be independent of the normal "stop" setting of the drive for day to day use.

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            • #7
              Strictly speaking according to the code there should be a contactor a head of the VFD for E-stop purposes, the normal control Stop input is used for normal stop/start operation, just about all of the manuals show the contactor needed.
              Max.

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