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  1. #1

    Suitable relay for three wire control on a VFD

    Hello folks
    I have been walking through the steps with another forum member on setting up a VFD for his saw.
    Unfortunately the VFD does not have a relay OR COMMON for three wire control/push button station.
    Can any of you guys point me in the right direction to find a suitable relay for him?

    Any help would be much appreciated.

    Many thanks in advance.
    Tom
    Last edited by Tom Trees; 10-11-2019 at 7:21 PM. Reason: Common, or reset is the part I need in between NC and NO button station

  2. #2
    Hello again
    Guessing maybe I'm not being specific enough, as I have asked this question before for my own VFD's in passing with no response.

    I am not looking for a relay to isolate the supply.
    This is for a home workshop, not for a business, so the need for the 10 second machine stop and isolated rule does not apply.
    The VFD is in an enclosed hefty cabinet so dust or damage won't be a factor in the decision.

    It is merely for between a NO start push button and a NC stop push button.
    It is for a tablesaw, so I have advised him that it was safer to have a hands free paddle switch for his stop button, rather than two wire control using a toggle switch
    He has made a paddle for his buttons already.

    Hope this clears things up a bit.
    Sorry for any confusion or vagueness.
    I have an in-built relay on my VFD, so I have no experience with this.
    Thanks again
    Tom

  3. #3
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    What current and voltage rating? Solid state or mechanical?
    David

  4. #4

    Smile

    Quote Originally Posted by David Buchhauser View Post
    What current and voltage rating? Solid state or mechanical?
    David
    Thanks for your response David
    I think the VFD has 12v terminals, but I'm unsure TBH.
    And I don't know what I need regarding solid state or mechanical.

    I'd imagine that most VFD's have the same voltage output for external switch controls.

    My VFD is the same as the one my mate has, but his relay does not work from the get-go.
    My relay failed upon swapping my VFD over to the tablesaw (for no reason whatsoever I might add) as I wanted three wire control on it.
    It got no abuse during the long voyage... 6 feet away from the bandsaw.

    No problem as I had an older one the same so just swapped out the front panel and it works flawlessly.
    Seems a problem with the new batch of Huanyangs.


    I bought a newer VFD with auto shutoff fan control to put onto the bandsaw,
    and works via two wire control with a simple toggle switch.

    Here's what my setup was on the bandsaw.
    It seems strange to me, that its not a straight up answer, as I believe the Teco FM50 needs a relay also for three wire control for a push button station.
    Here's some pictures, in hope that it may clear things up a bit.
    If not I can disassemble my old Huanyang that got fried from the motor stalling and give you a more in-depth look at it.
    It is the newer batch of them, so will definitely be exactly the same as my friends one.

    As you can see I'm using bog standard push buttons, and the relay goes in-between into that RST terminal (nothing to do with the RST mains 230v input terminals)


    DSCN2230.jpgDSCN2205.jpg

    I'm gonna guess this might be the most useless information ever, that I'm giving you.
    I hope you are not frustrated by my lack of knowledge.

    Awaiting a scolding
    Thanks
    Tom
    Last edited by Tom Trees; 10-12-2019 at 2:45 AM.

  5. #5
    Looking at the manual now, and it states no additional information on the voltage or anything else is relating to the multi input control circuit terminals.
    This RST relay terminal is titled as reset, FOR is forward, and DCM is described as common terminal of digital and control signals.

    Surely there are folks using a Teco FM50 or similar on a tablesaw or spindle moulder etc, and have hands free off switches and not using a toggle switch?

    Are you all doin the Holmgren paddle?

  6. #6
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    https://www.factorymation.com/22PBA2-N4P-200-00

    This is a simple contactor with the green button normally open (NO) and the red normally closed (NC). It's what the TECO expects. You need 3 wires from the VFD to the box: common, start, stop. The voltage is low, 12V I think. I used some leftover telephone cord (old, old leftover, four wire red/green/yellow/black), just about anything will work.

    I don't have a photo handy, but my tablesaw I have two 4x6 paddles and a 'finger' on a common rod that goes from left to right just under the fence, the wooden finger just touches the stop button. I don't have to look to slap one of the paddles -- left hand or right -- and shut off the saw.

    For a second saw I have a simple off/on switch, but it's a red mushroom: pull for on, push for off. I don't have to look for that either, but it is smaller.

    Terry T.

  7. #7
    So you're saying the Teco actually has what I'm calling a relay?

    What you're calling a common is what I need.

    Should I edit my post and change the word relay with common, or is a relay also called a common?

    I thought the Teco FM50 needed one for three wire control, but I'm obviously mistaken, I shall edit my title, and a few bits.
    One step closer
    Thanks Terry
    Tom

  8. #8
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    Quote Originally Posted by Tom Trees View Post
    So you're saying the Teco actually has what I'm calling a relay?

    What you're calling a common is what I need.

    Should I edit my post and change the word relay with common, or is a relay also called a common?

    I thought the Teco FM50 needed one for three wire control, but I'm obviously mistaken, I shall edit my title, and a few bits.
    One step closer
    Thanks Terry
    Tom
    Here is a solid state relay. It can be controlled by a DC voltage between 4 and 32 volts. It is used to switch an AC voltage (on or off). It has a maximum current rating of 50 Amps. I would need to see the schematic or wiring diagram of what you are trying to achieve in order to provide any more useful input.
    David
    (Electrical Engineer)


    https://www.alliedelec.com/product/i...-50a/70174931/

    solid state relay.jpg

  9. #9
    Thanks David
    I could give you a schematic but the picture is as helpful as it.
    The part I'm after should only be the price of a pint of beer, as its on a cheapo VFD.

    What happens without this component is, one has to keep their finger held on the push button switch for the motor to run, take your finger off and it stops.
    To explain this, I will break it down in the simplest way I can, which is the bog standard test for wiring switchgear on an VFD/inverter, (its what the pro's do)
    Normally folks use short wires and figure out the configuration like this.

    Forgetting the switches for the minute, one can do the same thing with short wires on this VFD I have.

    All one needs to do the test is have 4 short wires
    1 wire in FOR, 1 wire in DCM, and 2 wires crammed in RST.

    Twist or hook the DCM wire with one of the two RST "Common" wires.
    FOR can be struck off the other RST "Common" the motor runs. (the FOR just needed to be struck momentarily and is not connected to anything)

    To stop the motor unhook/separate the DCM with the other RST "Common"

    It's that simple.
    If I can just find the part as there's no information about this "common"
    Probably the worst name it could be possibly called if ones searching that into Google

    Any help appreciated to source this cheapo part.
    As said, I can open it up as I have a spare drive if anyone's interested.
    Way over my head, but someone may find it interesting.

    Thanks again
    Tom
    Last edited by Tom Trees; 10-11-2019 at 9:47 PM.

  10. #10
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    I just use a $10 powermatic paddle switch. With one wire to run, one to ground/common. Sure it's a 20 amp 240 rated switch but it's what I had. A tiny toggle switch will do the same. It essentially functions like a light switch or toggle switch but it has a button for start and a button(paddle) for stop.

    Ground/common is often referenced, in describing switches and buttons as they will operate in several ways. For low voltage stuff like this they may be pull up or pull down where you essentially will either short the terminal to VCC (maybe 5 or 12V) or ground(or common) the controller will read this change of state, its not exactly like a light switch in some cases, but its still a switch.

    It looks like in your case you can use any normal on/off maintaining switch between DCM and FOR.
    Last edited by Steven Cooper2; 10-11-2019 at 10:35 PM.

  11. #11
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    The FM50 doesn't need an external relay for three-wire control. I borrowed this illustration from OWWM:

    IMG_1137.JPG
    Chuck Taylor

  12. #12
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    Quote Originally Posted by Tom Trees View Post
    It is for a tablesaw, so I have advised him that it was safer to have a hands free paddle switch for his stop button, rather than two wire control using a toggle switch
    Tom
    I have a paddle switch similar to the one shown below on my 5HP cabinet saw. This paddle switch will work in conjunction with your VFD to control the 3 phase AC voltage to your 3 phase motor. You can still use your momentary push button switches or toggle switches to control your VFD, then use this paddle switch to connect/disconnect the 3 phase AC voltage output from your VFD to your table saw 3 phase motor. If you can provide the make and model of your VFD, I will draw you a connection diagram to show you how to wire it up. The wiring diagram for your VFD would also be helpful.

    Maybe also consider editing your profile to show your location (Ireland). This might make it easier for members to provide helpful responses in the future.
    David





    Paddle switch front view.jpg Paddle switch side view.jpg
    Last edited by David Buchhauser; 10-12-2019 at 10:04 PM.

  13. #13
    Hi David
    Its the 3hp/2.2KW Huanyang VFD, I could recite the model HY02D223B in my sleep, I have studied just about every single aspect of it
    that is online, I know the in's and outs of it...
    That's not to say I fully understand how to fix it if the traces melt, but I can say I've done some homework on this VFD in particular
    The factory reset ALA ribbon cable trick if one uses a potentiometer and it cuts out
    Making the fan "shut up"
    How to fit the missing parts for a braking resistor to work
    And probably a few other things that don't come to mind now.

    Its probably a matter of time before someone documents what I'm after.
    It would be nice if I could start the ball rolling so some experienced person could come along and document it properly, in a knowledgeable professional fashion.

    The documentation on these is terrible, and I don't think it would be of much help.

    My post disappeared, and this is all that was saved.
    To sum it up again
    Its the switches for the VFD that is the problem, it wouldn't be if it was just two wire control.
    I think it seems unnecessary to have another switch to isolate power to the motor
    and probably expensive to get a switch rated for the motor output, that also controls a two wire control signal to the VFD.

    I walked my friend through the parameters explaining what they all meant, as he knew nothing more than wiring a plug at the time.
    He got the saw for a bargain and stumbled across my posts on a UK forum, as I have the same saw and am using the same inverter.
    I do not wish to overwhelm him, and to be perfectly honest I would rather learn how to do this first myself than be advising him to do something I haven't done before.
    I am not knowledgeable about this, only knowledgeable about certain basic aspects I can understand.
    so it could be a recipe for disaster.
    These things scare the dung out of me, and I'm very cautious and repetitive about the dangers involved if giving advice on them, but at the same time feel obliged
    as I can save the professionals from doing the basic explanation, so they can have more time to explain the more complicated things.
    I like to throw a wee question in now and again.

    I just imagine that the common could be either fixed or that it could be replaced for the price of a bag of chips...sorry French fries
    I might have a chat with "Cindy" and see what they say, if its not something straight forward I might be needing some help and will report back.
    They are very nice to talk with, although the language barrier can be a bit of a challenge,
    We shall see.
    Thanks David for your perseverance, and to all who chimed in.

    Tom







    Last edited by Tom Trees; 10-13-2019 at 1:05 AM.

  14. #14
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    So it sounds like what you are after is to connect some sort of "paddle" switch directly to the VFD control inputs (FOR, REV, etc.). You are not interested in simply installing the "paddle" switch between the VFD outputs (U,V,W) and the motor. Am I correct in my assumption?




    Huanyang VFD.jpg

  15. #15
    Yes David
    I do not wish to involve the U,V,W motor terminals,
    and only want to have a separate start and stop button that goes into those small terminals for EXT switchgear.
    I don't want to isolate anything.

    The momentary push buttons do not work correctly on my friends inverter since the common is defective.
    The result of this defective part means that the motor will only run if his finger is held down on the start NO momentary button.

    If the common worked, he would not have to hold his finger on this button, and would run until he hit the stop NC momentary button.

    That's why I was saying that a toggle switch will work since its a permanent signal, the trouble is that a toggle switch does not make it straight forward to work with a paddle
    and takes some engineering like in this video @ the 5 minute mark into the demonstration.


    It looks like a bit of an awkward setup compared to a hinged plank with a dowel in it.

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