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Thread: Seeking VFD Advice

  1. #1

    Seeking VFD Advice

    Several months back I bought a 1967 Northfield 12" jointer and received lots of good advice from people on this forum. I am just now getting around to trying to power it up. I need to order a VFD to run the machine. It is a three phase 3 HP motor and I have single phase power. I have been looking at the Hitachi WJ200-022SF VFD as a possible drive. It seems to fit the motor parameters well. The nameplate shows 10.4 amps at 220 volt three phase. I wanted to make sure I get everything I will need without having to make a separate order, so i have a question or two.

    First question is about a braking resistor. The Hitachi comes with ability to attach a braking resistor. Are they worth adding and how do you size them. The Hitachi accepts a few different OHM and Watt configurations. Some say 150% required torque for brake and some say 100%.

    Second question is how do most people wire the VFD to your power source. Do/can you create a plug that plugs into the 220 volt outlet or do most people remove the outlet and hard wire it to the VFD?

    Third question is about enclosures. The Hitachi recommends an enclosure to keep debris out. So do you generally mount these on the wall behind the jointer in a box with the power source wiring coming in the back?

    Finally, the jointer currently has an on/off switch on the front. Can I still use a switch with a VFD or do you turn the jointer on and off using the front panel of the VFD? If you can use a switch, should I reuse the one on the jointer or buy a new one?

    I don't even want to discuss wiring details at the moment. I'm just trying to figure out what to order so I have everything I need when the time comes to wire it. I'm sure once I have everything I will probably need to start another discussion about how to specifically wire it. These are some pictures of the motor plate and switch and wiring. image4.jpegimage2.jpegimage1.jpegimage0.jpeg

    As always, you all have been very helpful with past questions and I appreciate any help you can give me.

  2. #2
    Join Date
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    I am not qualified to give specific advice appropriate to the NEC, so I will tell you what I did on my machine:

    I mounted a small ventilated enclosure to the back of the machine and used some filter material over the air holes to prevent dust ingress. I think that SJ200 has a removeable operator panel. If not, you can order one with the drive. You mount that little panel in a convenient location and connect it with Cat 6 cable (also available as an option with the drive).

    I wired my VFD with a standard cord and plug.

    I noticed that the SJ200 does allow the use of a remote E stop button…a very good thing. In use you would use the remote panel for normal stop start and still keep the E stop button for bad days.

    Regarding the braking resistor…Can you have too much?

    Greg
    Last edited by Greg Quenneville; 05-09-2022 at 6:41 PM.

  3. #3
    Whether you need a braking resistor depends on how much inertia the cutterhead has and how fast you want it to decelerate. If the vfd shuts down at the default deceleration rate you can either increase the ramp down time or add a braking resistor. If you want a rapid stop you should probably plan on adding one.

    You should have a disconnect switch in sight of the machine or a plug for safety during maintenance.

    You can buy or make an enclosure. You want to keep dust out and avoid heat buildup.

    You can use the existing start/stop buttons but you will have to program the vfd to use them. I use the remote keypad on the Teco vfd on my lathe but the blister buttons are a pain to use. What you can't have is a switch between the vfd and the motor.

  4. #4
    Join Date
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    The Hitachi WJ VFD's are considered a premium VFD. I have a couple and they are the only ones that would not work directly out of the box without setting a couple of parameters first. Setting the parameters isn't hard but figuring out which ones to set takes a bit of time. You can use a laptop and USB cable to set the parameters through Hitachi's custom software that can be downloaded for free in leu of setting them via the front panel buttons.

    I always make a 220v power cord so the VFD/machine can be unplugged easily for maintenance and moving it else where. I have never hard wired my VFD's.

    I REALLY doubt you will need a braking resistor on your jointer. There is some breaking capability in the VFD out of the box. If it isn't enough for you then you can add a braking resistor later... but I highly doubt you will find a need to.

    The VFD should be wired directly to the 3ph motor. You can use the blister buttons on the VFD to start and stop but they aren't the easiest to push. You can use pretty much any two normally open buttons for start and stop since they are just carrying 12v control signals to the VFD not 220v line voltage. The buttons currently on your jointer look like they "should work". In standard contactor control buttons the start button is normally open and the stop button is normally closed. You will need 2 normally open buttons to control the VFD. Most stop buttons I have come across have an unused normally open contact that you can use to control the VFD stop function. Open the case on your current buttons and see if there is an extra unused contact on the stop button. If there is an extra contact you should be good to go.

    Most of my VFD's are not in enclosures and mounted to avoid the chip flow of the machines to keep them from building up saw dust too quickly. The VFD's I have mounted in enclosures also have filtered fans to keep the air in the enclosure moving and heating up too much. Enclosure mounting, adding fans, wiring, etc. can become quite a project. I would suggest just surface mounting the VFD on the machine away from the chip flow and giving the heat sink on the VFD an occasional blow with shop air.

    If it were me I would just use a cheap Chinese VFD for the jointer. I use a Hitachi on my metal lathe where I used the original lathe rotary switch, a separate potentiometer for speed control, jog forward/reverse buttons, a breaking resistor, e-brake paddle button etc. A jointer will need none of these so the cheap Chinese VFD's will work fine.

    The current motor contactor on the jointer can be removed, it should not be needed any more.

    You can get a big paddle button or E-Stop button to mount to the front of the jointer in a place that can be hit by a knee in case of emergency. You can wire this to the VFD e-stop signal and have the motor stop near immediately with a braking resistor. I would not use quick braking for normal operation as it can be set to be quite abrupt. Or just use it on the normal stop input and it will work like the jointer was originally intended to. The only machine that I have an e-stop button on with fast braking is my metal lathe. All other machines wind down fast enough that normal stop and spin down works fine. Even without a braking resistor my saws stop quicker with a VFD than when they were run on 3ph line current or a rotary phase converter.
    Last edited by Michael Schuch; 05-09-2022 at 8:23 PM.

  5. #5
    Join Date
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    I doubt you need braking, much less a resistor. Coast down is probably fast enough. I feel safe in removing wood while the cutter is spinning on a jointer.
    I would use a cord and plug to connect the vfd to the power.
    I would also use a short cord and plug from VFD to motor. That will make the install much easier. Those do not need to match anything else you have, so anything that can be had, cheap, is fine. I find a matched set at habitat and store them away for later.
    Yes, reuse the existing switches if you like them and their location. While you are at it consider adding another off switch at the outfeed end. Possibly a foot operated off switch.
    Lockout reverse on the VFD so it can not happen by accident.
    I doubt you will ever vary the rpm after the first time.
    Bill D
    Last edited by Bill Dufour; 05-09-2022 at 8:20 PM.

  6. #6
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    Unclear if the 10.4 amps is the vfd or the motor?

  7. #7
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    It is easy to use the start/stop buttons currently on your machine, from a wiring point of view. If the current buttons are in a handy location, then reuse them. That was the perfect way for my Moak bandsaw, where the foot brake also turns off the switch. If they aren't in a good location, move them or use something else. Sometimes I've had a plug between the VFD and the machine, for ease, sometimes not.

    Terry T.

  8. #8
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    3hp Teco FMX would my recommendation.

    Hard wire from a breaker to the VFD. Hardwire from VFD to jointer. You can have a plug in either end, but plugging in the wrong wouldn’t be good.

    I basically just have a sheet metal shield over the VFD to keep chips out.

    No need for a breaking resistor on a jointer. A 12” head slows down fast enough.

  9. #9
    Bill, the 10.4 amps came from the motor plate. It said 10.4 amps at 22 volts.

  10. #10
    Michael, thanks for the information. I don't know if you looked at the pictures I downloaded, but by motor contactor, do you mean the box where the motor, switch, and plug are wired from? I assume that is it. That box sits under the outfeed table wheel on the end of the machine. That seems like a good place to mount the VFD because all the wiring is already there coming from the motor and from the switch. I would just need to make a cord to plug into the outlet.

  11. #11
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    For my lathe the VFD fan runs all the time so... I used the original contactor to supply power to the vfd. That way when the lathe is done no more fan noise. Of course I only shut the contactor off after the VFD has stopped the lathe.
    Bill D

  12. #12
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    Quote Originally Posted by Larry Feltner View Post
    Michael, thanks for the information. I don't know if you looked at the pictures I downloaded, but by motor contactor, do you mean the box where the motor, switch, and plug are wired from? I assume that is it. That box sits under the outfeed table wheel on the end of the machine. That seems like a good place to mount the VFD because all the wiring is already there coming from the motor and from the switch. I would just need to make a cord to plug into the outlet.
    It looks like the contactor and overloads are inside that box. If the vfd will fit that is a nice box. maybe make a sheet metal extension so it will fit. Or cut a hole in the back side and mount it on top of another box
    Bill D

  13. #13
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    Quote Originally Posted by Larry Feltner View Post
    Michael, thanks for the information. I don't know if you looked at the pictures I downloaded, but by motor contactor, do you mean the box where the motor, switch, and plug are wired from? I assume that is it. That box sits under the outfeed table wheel on the end of the machine. That seems like a good place to mount the VFD because all the wiring is already there coming from the motor and from the switch. I would just need to make a cord to plug into the outlet.
    Yes, that is what I was referring to. The big box that says do not turn this wheel. I agree that it appears to be a good place to mount the VFD.

    A motor contactor is a big relay that engages to supply 3ph power to the motor when you press the start button. Usually there will be overloads (as Bill pointed out) in the same box that will open if too much current is going through the motor to keep the motor windings from burning out. The VFD will replace all these functions.

    When the VFD is plugged in (receiving 1ph power from the wall) it will be powered on even if the motor isn't running. I usually use a simple power switch like this: https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    to cut power to the VFD when I am done for the night. The switch I linked to is a 3ph switch, I just used 2 of the 3 contacts to switch 1ph power to the VFD. It really doesn't hurt anything if the VFD is running all the time it more just disturbs me that it is there sucking down minute amounts of power when I am not there. Plugging the machine in the first time you use it for the day then pulling the plug when you are done for the day is another way to cut power to the VFD. I have a couple machines without the power switch that I plug in and unplug as described, for the $10 for the switch I recommend purchasing one. Some day I will wire in a power switch before the VFD for my machines that don't have one currently.
    Last edited by Michael Schuch; 05-10-2022 at 11:59 AM.

  14. #14
    Join Date
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    Agree with Michael on the power switch. And if you get a DPDT switch it can protect your VFD from lightning if the strike is not too hot.

    Wiring Diagram (I'm just guessing on wire sizes)
    - big wire from source thru wall plug and disconnect switch then to VFD (10 ga)
    - big wire from VFD to motor (12 ga)
    - big wire from VFD to external resistor if used ((10 ga)
    - small wire from VFD to control devices, start stop switch, E stop, whatever (24ga or as needed for durability)

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