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Thread: Installing VFD

  1. #1
    majohnson is offline Plastic
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    Default Installing VFD

    I'm finally going to power up my old Bridgeport, its been down since I moved. I'm switching to a Hitachi VFD, for the benefit of speed control given mine is an old step pulley model. Since I had to buy a new phase converter, it seemed like a good choice.

    On the side of my mill it has a Square D magnetic starter, at least thats what I think it is. It includes a breaker, but it also must step down the voltage because just below the starter box is a 110v receptacle. Installing the VFD replaces all the current controls, however is there a way to run power through the starter so I can still maintain the 110 outlet? Its handy for the dro and power feed power source.

  2. #2
    J.R. Williams is offline Hot Rolled
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    Feed the VFD from the magnetic starter and connect the motor to the VFD. This will retain a disconnect at the mill.

  3. #3
    majohnson is offline Plastic
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    By doing it that way, where would I connect my main power source? There are 3 leads that feed into mag starter, plus a ground were my phase converter feed power to mag starter.

    Thanks for the reply JR.

  4. #4
    nc5a is offline Plastic
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    majohnson,

    JR is right, you can power the VFD from the mag starter but it can get a little messy, electrically speaking of course. I just installed a VFD to power a 7.5 hp lathe so I'll try and give you a visual of what I did. Wires go from the new single phase 240V breaker installed in the load center to a new single phase 240V contactor with a 240V coil then to the VFD then out of the VFD directly to the motor. The reason for the 240V coil is so the control power comes from the same source as the motor, it's safer that way. Power for the DRO and work light comes from a 120V single phase breaker in the load center to the lathe electrical panel which had been stripped of all contactors, relays, timers, and transformers. The only things left were the terminal strips, panduit and internal wiring to switches, lights and motor thermal overload protection. I used the power switch on the lathe to power the VFD and the E-stop to kill power to the VFD. A separate .25 hp VFD was also installed to power the coolant pump and the coolant switch on the lathe turns it on and off.

    Most VFD's have a trouble/malfunction output contact that you can wire into the start circuit of the contactor supplying power to the VFD. That way if there is a problem with the VFD or you hit the emergency stop button (assuming one in wired in) power is removed from the VFD. VFD's live longer if you kill power to the input when trouble rears it's ugly head.

    There is of course much more involved getting a clean installation that is up to code and easy to operate. For instance power and control wires should be run in separate conduits, control wires should be shielded, shields should be grounded at the VFD only, ground wire/s should run from the load center to the contactor, to the VFD, then to the machine electrical panel. E-stop button should be installed.

    I know reading how to install a VFD is much harder than seeing photos or drawings but most VFD manuals that I've seen are pretty informative so you should be OK, Good luck. nc5a

  5. #5
    robvds is offline Cast Iron
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    Default

    Quote Originally Posted by majohnson View Post
    By doing it that way, where would I connect my main power source? There are 3 leads that feed into mag starter, plus a ground were my phase converter feed power to mag starter.

    Thanks for the reply JR.
    There were 3 wires from the converter but now there will be 2 because you will only feed 1 phase. Normally you use the outer 2 contacts of the contactor for single phase but you must ensure that the power for the starter's coil and the transformer for your 120v come off these 2 contacts. It would be cleaner to mount a little disconnect box instead of what is there. You will bring 2 hot, 1 neutral and 1 ground wire from the panel and that will give you 120v without a transformer.
    Rob

  6. #6
    majohnson is offline Plastic
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    Default Vfd

    Thanks for the reply's.

  7. #7
    majohnson is offline Plastic
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    Let me run this by and make sure I am up to speed on what you guy are telling me. My Hitachi VFD is WJ200, 110v input only with 220v 3 phase output. Currently I don't have 220v here, since I might be out of here in a couple of years, I don't want to spend the money to have a sub panel put in and run all the wiring. My current panel is full, new houses builders cut costs any way they can.

    Running current 110v to the mag starter, from there the starters output wiring minus a couple of leads goes to the input side of the VFD. Then the leads going to motor gets hooked up to the VFD output side has per the mfg instructions. Along with settings to the VFD programming.

    I have a fwd/rev switch that gets deleted along with wiring from the mag starter. I like the idea of the safety by retaining the disconnect portion of the mag starter and still having a 110v outlet on the machine. In a shop setting using the mag starter is slick way of installing the machine. If there is a problem it doesn't effect the balance of the shop, you have outlet for machine accessories.

  8. #8
    atomarc is online now Titanium
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    I read your last post, don't fully comprendo but will shoot my mouth off anyway! Silly to stick a contactor in front of a freq drive....wire it to a panel with appropriate wire and circuit breakers and call it good. Leave it alone...just like your microwave in the kitchen or the kitchen stove or the computer or whatever. You don't kill the power to the stove when you're done cooking soup do you...no, you turn the knob off. Same with the VFD, it's powered all the time but you turn the drive off with the logic button..the knob, just like the stove.

    The drive is always powered but the control (logic) isn't in RUN or REV...it's in STOP. Use your mag to control the logic functions.

    Stuart

  9. #9
    majohnson is offline Plastic
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    I deleated all the old electrical components and installed the VFD. Now I can't get the motor to power up, will the motor power up in the base settings? It seems like there are 2 way to program the unit, one using the codes through the key pad and the other using a jumper wire to connect logic inputs terminals. Is it one or the other or both? The manual list one then the other and I'm yet to find the answer. I'm trying to get Xmass presents finshed for the grand kids.

    My VFD is WJ200 007MF.

  10. #10
    atomarc is online now Titanium
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    I think it 'one or the other'...remote or panel, but not both. This is a parameter you must program into the drive.

    Stuart

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