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  1. #1
    Hi,
    I am new to this group and hopefully someone maybe able to assist me with my problem.

    I purchased a really old power hacksaw and I have refurbished it so it is like new. It is driven by a 0.5hp 6 pole 3 phase motor which was originally wired in star, I have now moved the links to the delta configuration so that I can run it off a variable frequency drive. I have recently purchased a cheap Chinese XSY-AT1 variable frequency drive and it runs the saw perfectly. My problem is that the power hacksaw has a simple 2 wire switch that stops the saw when it has completed its cut. When it was wired originally the stop switch was wired into the 3 phase starter and the coil dropped out so it wouldn't restart until the run button was pressed.

    I have been looking at the parameter settings but with me not being electrically orientated I don't know if I can wire this simple 2 wire stop switch into the inverter. I have set the parameters so that the keypad is inoperative and found that if I wire from the common terminal to the X4 terminal (run forward) using the simple 2 wire stop switch then it stops the saw at the end of its cut. The problem then is as soon as the saw is lifted the saw starts up again without pressing anything. Obviously this is a rather dangerous practice.

    I have looked at a few video's on YouTube but most show fitting the start/stop switches along with a new 10k potentiometer which I don't require as the speed of the saw is fine whether it is cutting a hard metal like stainless steel or soft material like brass. I have purchased 2 new momentary push button switches, a green one for start & a red one for stop but would like to know how to wire them in along with the original 2 wire stop switch.

    Any help would be appreciated. Thanks, John

  2. #2
    I talked about this inverter on my Youtube channel (routercnc). One of the early episodes in the drill press conversion series. If I understand what you need to do I think a latching relay arrangement would do it? The output contacts would control the run/stop X4, but other contacts on the output side would cut power to the coil itself so it wouldn’t start again until you armed it. There might be better ways but this was my first thought on it.
    Building a CNC machine to make a better one since 2010 . . .
    MK1 (1st photo), MK2, MK3, MK4

  3. #3
    Quote Originally Posted by oldshooter View Post
    Hi,
    I am new to this group and hopefully someone maybe able to assist me with my problem.

    I purchased a really old power hacksaw and I have refurbished it so it is like new. It is driven by a 0.5hp 6 pole 3 phase motor which was originally wired in star, I have now moved the links to the delta configuration so that I can run it off a variable frequency drive. I have recently purchased a cheap Chinese XSY-AT1 variable frequency drive and it runs the saw perfectly. My problem is that the power hacksaw has a simple 2 wire switch that stops the saw when it has completed its cut. When it was wired originally the stop switch was wired into the 3 phase starter and the coil dropped out so it wouldn't restart until the run button was pressed.

    I have been looking at the parameter settings but with me not being electrically orientated I don't know if I can wire this simple 2 wire stop switch into the inverter. I have set the parameters so that the keypad is inoperative and found that if I wire from the common terminal to the X4 terminal (run forward) using the simple 2 wire stop switch then it stops the saw at the end of its cut. The problem then is as soon as the saw is lifted the saw starts up again without pressing anything. Obviously this is a rather dangerous practice.

    I have looked at a few video's on YouTube but most show fitting the start/stop switches along with a new 10k potentiometer which I don't require as the speed of the saw is fine whether it is cutting a hard metal like stainless steel or soft material like brass. I have purchased 2 new momentary push button switches, a green one for start & a red one for stop but would like to know how to wire them in along with the original 2 wire stop switch.

    Any help would be appreciated. Thanks, John

  4. #4
    Many thanks for your response but I have removed the original starter from the saw whilst I was refurbishing it as it was fitted in 1968 when the saw was manufactured and was fitted with a 415v coil and associated thermal overloads. My intension all along was to fit a variable frequency drive as I haven't got a conventional 3 phase supply and knew that the drives have a soft start/stop facility so all the original electrics were removed. All I did was to change the straps on the 6 pole motor from star to delta thus allowing me to run it from a 230v single phase supply. So unfortunately I can't do as you have suggested in your response to my initial query but thanks anyway for taking time to assist.

  5. You can usually configure a VFD to accept one input for start and one for stop, using momentary switches. This causes the VFD to start and stay on (when you press the start button) until you press the stop button. That's how my lathe is set up.

    I'm not familiar with this particular model but I'd be very surprised if you can't configure it to work in that latching mode. Looks as if the manual is here http://www.jinlantrade.com/ebay/invertermanual.pdf (16MB)

    Pages 36 and 37 seem to show how to connect a normally closed switch (stop) in series with a normally open switch (start) and what parameters to set to achieve what you want. Dunno if anyone here has done this with these inverters or whether your switches are suitable. The manuals are sufficiently vague to make it hard to be certain what they are on about.

  6. #6
    Thanks for the advice and the link, I will have a good look at this and let you know how things progress.

  7. #7
    FWIW I would just put a switch in the 240V feed to the VFD.

  8. #8
    Many thanks for your advice.

  9. #9
    Quote Originally Posted by ngwagwa View Post
    FWIW I would just put a switch in the 240V feed to the VFD.
    That's not a good idea VFD's don't like being switched off/on like this plus they have to discharge their capacitors so if the outputs to motors are not disabled, which they won't be just switching off while running then it will continue running until caps are drained which isn't safe.

    It's simple to do Like Muzzer says. It's a simple latching setup.
    -use common sense, if you lack it, there is no software to help that.

  10. #10
    I didn't think that any VFD liked being switched on & off due to the capacitors holding their charge etc. I am going to follow some earlier guidance with a simple latching set up.

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