how to use vfd for old cnc mill

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Thread: how to use vfd for old cnc mill

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    Default how to use vfd for old cnc mill

    i acquired an old Lagun 250 cnc mill. Everything worked when it was setup with its previous owner. It has a 230V 3 phase plug. I don't have 3phase in my shop so i ran a 220V single phase cable to the mill and i bought a single to three phase VFD. I originally assumed i could just wire a receptacle to the output of the vfd and plug the mill in but after looking at the VFD manual it mentioned it is only suitable for running a motor.

    looking inside the mill, it seems the 3 phase input goes through two transformers. the first transformer - i'm not sure what it does. the 2nd transformer makes single phase 120v that powers the controls and computer i think.

    do i need to disconnect the output of the final transformer and wire that directly to a 120v plug? Where do i inject the VFD output?

    how to use vfd for old cnc mill-img_20200624_210402588-jpg

    how to use vfd for old cnc mill-img_20200624_210331164-jpg

    how to use vfd for old cnc mill-img_20200624_210357526-jpg

    how to use vfd for old cnc mill-img_20200624_210354101-jpg

    how to use vfd for old cnc mill-img_20200624_211146760-jpg

    Thanks in advance!

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    Member machinehop5's Avatar
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    Default Re: how to use vfd for old cnc mill

    ...the only things 3 Phase are the Spindle motor and coolant pump most likely. ....you can use 220v single phase and start the machine up....figure out which two of the three Power Inputs to hookup to.....trace the two wires on Trans #2 (GE) back to Main fuse Inputs will tell ya. As far hooking up your VFD maybe a little involved if, you want to control it from the CNC Control. M3 M5 and S codes. Not easy but, can be done (I thnk) in the Dynapath 20 PLC. other Zoners maybe able to help you with more information soon.



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    Community Moderator Jim Dawson's Avatar
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    Default Re: how to use vfd for old cnc mill

    It looks like the only thing that uses 3 phase is the spindle motor. You would want to connect the spindle motor directly to the VFD output.

    The big transformer looks to be the power transformer for the servos, and also looks to be single phase. I assume 230V input.

    It looks like the wire from the bottom of the left main fuse only goes to the spindle motor contactors directly below it. Maybe also a coolant motor contactor.

    The other two main fuses seem to provide 230V single phase to the rest of the hardware.

    You are going to have to do some rewiring to make it work.

    Remove the left fuse

    Connect your 230V single phase to the top of the middle and right fuses.

    Connect the VFD input to the bottom of the middle and right fuses

    Remove all of the power wiring from the spindle motor contactors, leaving the coil wiring intact.

    Use the motor contactors as relays to switch the control circuit on the VFD.

    Again connect the spindle motor directly to the main output of the VFD, normally marked U, V, W. Properly ground everything.

    .
    .

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: how to use vfd for old cnc mill

    Hello.

    What you take as a second transformer is a line filter. It is used to minimize the amount of electric "noise" generated at the switching transistors from being fed back into the power lines. Some disk capacitors might also be connected to it.

    For some VFDs that filter is an optional external component and some already include it as in the one you have. There are even some line filters that are connected between the VFDs and the motors they drive. Their function in this case is to protect the switching transistors from the EMF generated at the motor in particular when slowing down as the motors work as generators at least for a moment. That is also the reason why some VFDs also use external power resistors. They help dissipate the excess charge fed back by the motors.

    I don´t know what type of filter your VFD has. The VFD to line or the VFD to motor but most probably the first one.

    In reference to its use you should consider that the actual power obtainable from the VFD must be derated when connected to two lines instead of three. To be on the safe side estimate an actual loose of at least 40%. If your drive is a 3 HP unit you should drive a motor no bigger than 1.8 HP.

    I hope this clears up some things.

    I noticed that you already got ideas on how to connect this drive. I hope it al works well

    Best regards.



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    Community Moderator Jim Dawson's Avatar
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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by BBMNet View Post
    Hello.

    What you take as a second transformer is a line filter. It is used to minimize the amount of electric "noise" generated at the switching transistors from being fed back into the power lines. Some disk capacitors might also be connected to it.

    For some VFDs that filter is an optional external component and some already include it as in the one you have. There are even some line filters that are connected between the VFDs and the motors they drive. Their function in this case is to protect the switching transistors from the EMF generated at the motor in particular when slowing down as the motors work as generators at least for a moment. That is also the reason why some VFDs also use external power resistors. They help dissipate the excess charge fed back by the motors.

    I don´t know what type of filter your VFD has. The VFD to line or the VFD to motor but most probably the first one.
    That is not correct. There was no VFD in the original system. There is no line filter supplied with the VFD, it is a separate item. The second large transformer in the pictures is the power transformer for the servo drives.

    In reference to its use you should consider that the actual power obtainable from the VFD must be derated when connected to two lines instead of three. To be on the safe side estimate an actual loose of at least 40%. If your drive is a 3 HP unit you should drive a motor no bigger than 1.8 HP.
    Derating is only done in the case that the VFD is not rated for single phase input. If the VFD is rated for single phase input, it will drive a motor at it full rated power on single phase.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by Jim Dawson View Post
    That is not correct. There was no VFD in the original system. There is no line filter supplied with the VFD, it is a separate item. The second large transformer in the pictures is the power transformer for the servo drives.



    Derating is only done in the case that the VFD is not rated for single phase input. If the VFD is rated for single phase input, it will drive a motor at it full rated power on single phase.
    You would have a hard time finding a single phase rated VFD Drive to run a machine that size which would need a minimum of a 5Hp VFD Drive, so derating is always a norm above 2Hp

    Mactec54


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    Default Re: how to use vfd for old cnc mill

    I have retrofitted a few in the past, similar to what you have, the servo drives look like old Westamp series, if or when they fail, you may want to fit modern types such as A-M-C etc, if Westamp, they use a tach feedback which you can disregard for the more modern version that operate in torque mode.
    Al.

    CNC, Mechatronics Integration and Custom Machine Design

    “Logic will get you from A to B. Imagination will take you everywhere.”
    Albert E.


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    Default Re: how to use vfd for old cnc mill

    THANKS EVERYONE. I'll get to work tracing wires and drawing a wiring diagram and then post it back here for confirmation on what things to disconnect and where to insert the new voltage sources. I dont want to fry anything, i'm guessing parts are hard to find and I want to avoid converting this to modern parts right now - maybe down the road once i realize how much of a PITA the interface on this thing is (I have a little experience doing CNC on a similar era conversational cnc control)



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    Default Re: how to use vfd for old cnc mill

    Would i be better off just tracking down a 3 phase motor to use as a rotary converter? if i go that route, i can just plug the mill in without any modifications right?



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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by jaysihn View Post
    Would i be better off just tracking down a 3 phase motor to use as a rotary converter? if i go that route, i can just plug the mill in without any modifications right?
    If cost does not matter....yes and yes, because that way you would not have to do anything to machine wiring.

    I noticed you didn't mention in any post about the Model/Brand VFD you have. Do you have a pdf link for the manual?...How big is it? Would it fit/mount inside the Cabinet?

    DJ



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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by machinehop5 View Post
    If cost does not matter....yes and yes, because that way you would not have to do anything to machine wiring.

    I noticed you didn't mention in any post about the Model/Brand VFD you have. Do you have a pdf link for the manual?...How big is it? Would it fit/mount inside the Cabinet?

    DJ

    this is the one i bought. https://www.ebay.com/itm/283047413319

    i might be able to fit it inside somewhere.

    i was looking into making a rotary convertor using a bigger 3 phase motor. I've found a few 10hp or more motors for <$200 so that is an option but what I dont like is that I think i would have to have that on all the time when using the mill. that includes programming through the conversational interface, moving axes to setup the part and zero, etc. I think that would be very inefficient for me.

    i'm waiting on the wiring diagram from Lagun...



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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by jaysihn View Post

    i'm waiting on the wiring diagram from Lagun...
    That might be a long wait..



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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by machinehop5 View Post
    That might be a long wait..
    still waiting on the rep from Lagun (he did say he would send them though)

    but another forum member scanned and sent these. Thanks JSantos

    i attached all 10 pages of wiring diagrams.


    i think all i need to do is this...
    how to use vfd for old cnc mill-wiring-mods-jpg
    for now i'm saying to just disconnect the coolant motor - i can either try to swap in a 1ph down the road or maybe run dual VFDs? the previous mill owner had opted to build his own coolant system which sits next to the mill and has its own reservoir so i can just use that for now while i figure out why he bypassed the original.

    Attached Files Attached Files


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    Community Moderator Jim Dawson's Avatar
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    Default Re: how to use vfd for old cnc mill

    Close. Remove the 1M1 and 1M2 contactors along with the overload and attach the VFD directly to the motor. Also remove the 3 phase suppressor from the motor.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: how to use vfd for old cnc mill

    could you explain that portion of the diagram to me? aren't IM1 and IM2 used to flip the direction of the spindle? I figured once i create the 3 phase and get it connected where i showed, all the relays/contactors should work as originally designed.

    what happens if i leave the suppressor connected? is it going to cause issues to the VFD?

    how to use vfd for old cnc mill-wiring-spindle-jpg



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    Community Moderator Jim Dawson's Avatar
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    Default Re: how to use vfd for old cnc mill

    You never want to disconnect the VFD from the motor. This can damage the VFD. The VFD must be connected directly to the motor and start/stop, and reversing is done with the VFD control terminals, as well as the speed control. You can use the original motor contactors as relays to switch the VFD controls, after removing all of the motor power wiring from the contactors.

    The external suppressor may interfere with the VFD operation, and the VFD will provide this protection.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by Jim Dawson View Post
    Close. Remove the 1M1 and 1M2 contactors along with the overload and attach the VFD directly to the motor. Also remove the 3 phase suppressor from the motor.
    If it is a Reactor it will protect the VFD Drive, what they are calling a suppressor may well be a Reactor

    Mactec54


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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by mactec54 View Post
    If it is a Reactor it will protect the VFD Drive, what they are calling a suppressor may well be a Reactor

    Look at the way it is wired in, it is not a reactor. Most likely a R/C suppressor. No reason for a reactor on a non-VFD system as the original.

    Jim Dawson
    Sandy, Oregon, USA


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    Default Re: how to use vfd for old cnc mill

    Quote Originally Posted by Jim Dawson View Post
    Look at the way it is wired in, it is not a reactor. Most likely a R/C suppressor. No reason for a reactor on a non-VFD system as the original.
    It's there to protect the starters and the motor it' also helps with the Harmonics being feed back into the power system they have it on the coolant pump supply also it show this machine was most likely for the European market where this is a requirement

    Mactec54


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    Default Re: how to use vfd for old cnc mill

    got to love zoners..one more file might need sometime down the road. I am guess those axis amps are SD1520-10's

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