My new VFD is Delta and my 1930 motor is Wye
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  1. #1
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    Default My new VFD is Delta and my 1930 motor is Wye

    I have at least one problem. My new VFD only supports Delta, and the motor which converted my 1904 LeBlond from steam power to electric in the 30s is Wye.

    The motor is a 9 wire unit so I can rewire it for Delta. However the plate on the motor specifies Wye connection for moth high voltage and low.

    Will I abuse the motor by converting it to Delta? The current will increase, but is that typically a problem in these old heavy motors? (the starters in my old Flathead Fords love to run on 12V rather than 6!)I would like for this motor to see its 100th birthday...

    And if Delta will not damage it, how will the power curve change?

    I may have a 2nd problem. I only read the "fine print" in VFD instructions and determined that it was intended only for Delta after connecting it to the motor. When the motor is switched on the VFD faults out instantly. The motor shaft does not even twitch. Even if the VFD was intended for Delta I would have expected it to take some milliseconds for the additional current to create a fault. So is my new VFD DOA? If so perhaps I just need to purchase a VFD which supports Wye.

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    Quote Originally Posted by Dr. Hillbilly View Post
    I have at least one problem. My new VFD only supports Delta, and the motor which converted my 1904 LeBlond from steam power to electric in the 30s is Wye.

    The motor is a 9 wire unit so I can rewire it for Delta. However the plate on the motor specifies Wye connection for moth high voltage and low.

    Will I abuse the motor by converting it to Delta? The current will increase, but is that typically a problem in these old heavy motors? (the starters in my old Flathead Fords love to run on 12V rather than 6!)I would like for this motor to see its 100th birthday...

    And if Delta will not damage it, how will the power curve change?

    I may have a 2nd problem. I only read the "fine print" in VFD instructions and determined that it was intended only for Delta after connecting it to the motor. When the motor is switched on the VFD faults out instantly. The motor shaft does not even twitch. Even if the VFD was intended for Delta I would have expected it to take some milliseconds for the additional current to create a fault. So is my new VFD DOA? If so perhaps I just need to purchase a VFD which supports Wye.
    You say "when the motor is switched on"... are you meaning the VFD is already in "run" mode and you have a switch between the VFD and the motor which you close and you're expecting the VFD to be able to start the motor that way?

    If so, that's not the recommended way (you should allow the VFD to start the motor rather than having a switch in between), and if you're determined to do it, ignoring your wye vs delta issue, you would need a VFD sized for the "locked rotor amps" of the motor which would be a much bigger VFD.

    Please also post what code the VFD shows a fault, and which VFD it is.

    -Phil

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    Can we get VFD models, motor dataplate, and what your supply is?

    As above, you need to not open or close any switches between the VFD and motor under load. The motor needs to be connected to the VFD any time the VFD is outputting, or the VFD needs to be sized for the motor *starting current*, not run current and programmed appropriately.

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    A basic V/Hz VFD should essentially not care or "know" what the motor type is. The basic terminal characteristics of same-power motors of wye or delta are pretty much the same, as far as voltage and current. Not too surprising, if the power is the same, the drawn current at voltage will be pretty similar, differing only by issues of efficiency and power factor.

    I can think of no reason why a VFD should work fine with one and have overcurrent errors with the other, so long as both motors are set up for the same line voltage and frequency.

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    Quote Originally Posted by SomeoneSomewhere View Post
    Can we get VFD models, motor dataplate, and what your supply is?

    As above, you need to not open or close any switches between the VFD and motor under load. The motor needs to be connected to the VFD any time the VFD is outputting, or the VFD needs to be sized for the motor *starting current*, not run current and programmed appropriately.
    img_6586.jpgimg_6598.jpg
    Here is the data plate from the motor. Note that the connections shown are Wye for both low voltage and high. Most motors recommend Delta for low voltage and Wye for high voltage, but not this one.
    The second image is of the VFD statement that Delta rather than Wye should be used.
    img_6599.jpg
    The third image is of the error codes. I observe Err 1.
    I am on the road now, but when I get home I will try starting and reversing the motor with the VFD rather than the switch on the lathe.
    Input to the VFD is 220V, and output is 220V three phase.
    The VFD is a no-name import from China sold on Ebay, rated at 1.5 kW

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    Oh, heck....

    If I read that note rightly, they are just saying that if your motor is currently set up 380 wye, you need to connect it delta.

    Since the coils in a wye 380V are the SAME as those in a delta 220V, it is the same motor, just connected for the proper voltage as supplied from the VFD. With 380V, it is 220V from line to neutral (star point is at neutral voltage, but not connected to neutral)

    ANY motor connected for 220V line-to-line is going to work fine, and the internals will not matter.

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    Quote Originally Posted by JST View Post
    Oh, heck....

    If I read that note rightly, they are just saying that if your motor is currently set up 380 wye, you need to connect it delta.

    Since the coils in a wye 380V are the SAME as those in a delta 220V, it is the same motor, just connected for the proper voltage as supplied from the VFD. With 380V, it is 220V from line to neutral (star point is at neutral voltage, but not connected to neutral)

    ANY motor connected for 220V line-to-line is going to work fine, and the internals will not matter.
    Yes, almost,
    The motor is currently wired 220 Wye as shown in the motor's tag (not high voltage Wye). The wiring ID has survived the decades as they used metal tags with wire numbers stamped. So I can easily rewire for low voltage Delta. I just wanted to confirm that I would not damage the motor as some web sites claim that Delta wiring provides higher starting torque and a higher surge in starting current.

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    Hold the phone there.... If it is wired for 220 already, then just leave it alone, it will run OK.

    Point I made was that the delta wye instructions for the VFD were really just telling you to wire it up for the correct voltage. Motors that are usable on european 3 phase are not 220V line-to-line, but rather 380V, and wired wye for 380V. So to get the motor set up for 220V line-to-line, you have to wire them delta.

    It s NOT a requirement for a delta wound motor or a warning of any sort..... it is a reminder that the output is 220V line-to-line, so you need to wire the motor to match.

    ANY motor set up for 220V line-to-line, of a power the VFD is made to handle, will work fine.

    As for your faulting out issue, there must be a wiring fault, or similar issue that is causing the problem, it will not be the fact of the motor being "wye".... The VFD will work with either type, because either of them will draw the same current etc.

    I better add that IF you take a wye-wound motor that is made for 220V, and you rewire it delta by reconnecting coils, the NEW motor voltage will be about 127V line-to-line. That will NOT WORK with your 220V output VFD

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    Quote Originally Posted by Dr. Hillbilly View Post
    Here is the data plate from the motor. Note that the connections shown are Wye for both low voltage and high. Most motors recommend Delta for low voltage and Wye for high voltage, but not this one.
    The second image is of the VFD statement that Delta rather than Wye should be used.
    Herein lies the flaw in your thinking. That highlighted statement has ONLY to do with IEC designed motors (meaning designed for use in Europe and Asia), it is NOT true of NEMA (North America) design motors. Yours is an old Westinghouse motor, it is a NEMA design. So to get two voltages out of it, you have two Wye windings side by side. For the higher voltage, you put the two sets of each Wye leg in series, for the lower voltage you put them in parallel (referred to a "Y-Y"). But ALL of that is actually irrelevant, you just need to make sure your connection pattern matches your available supply source voltage, forget what the motor looks like inside.

    The VFD is a no-name import from China sold on Ebay, rated at 1.5 kW
    Problem #2; the cheap crap Chinese drive is not actually designed for or meant to be used here in North America, and they don't care that their manual is confusing or inaccurate.

    At one point this forum made a conscious decision to NOT support people who buy these cheap crap drives, because it means WE are facilitating their ability to undercut everyone else by providing free tech support. You got lucky because you didn't mention that until the end...

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    OK, the most elegant solution seems to be to pitch the VFD and build a rotary phase converter (I have found several good references on this site).
    It seems that with judicious selection of caps the sacrifice in efficiency and vibration will not be severe?

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    I don't like the VFD, now that it has been pointed out what it is (I missed that).

    BUT.... aside from the low quality of the VFD, there is nothing about the motor and VFD that makes them not compatible.

    You own it......Wire the motor for 230V, and use the system until tthe VFD shoots craps. Then you can make decisions about a next move.

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    Quote Originally Posted by JST View Post
    I don't like the VFD, now that it has been pointed out what it is (I missed that).

    BUT.... aside from the low quality of the VFD, there is nothing about the motor and VFD that makes them not compatible.

    You own it......Wire the motor for 230V, and use the system until tthe VFD shoots craps. Then you can make decisions about a next move.
    Sound advice.

    But I will start work on a rotary phase converter to replace the VFD when it dies. I have found good information on the design of the converters on this forum so I am not asking anyone to repeat the information already posted, but if you have further advice I would be very interested.

    Phil pointed out that the VFD may not like being left in RUN and starting and reversing the machine from its old switch. I had planned to hide the VFD and preserve the vintage feel of my belt-drive machines. If this is not feasible I will want a rotary converter anyway. I want no VFDs or DROs hanging off of machines built between 1896 and 1904.

    In my defense I did not know that the forum did not welcome the cheap VFDs, and I usually buy cheap when I am exploring a technology which is new to me. That way I get through my learning curve without destroying anything of great value. Then I can make better informed decisions in the purchase of "keeper" tools.

    Thanks for your help!

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    You flat cannot USE the VFD in a switch on and switch off at the motor mode....... Not unless you oversize the VFD to handle inrush.

    The other stuff about killing the IGBTs etc, is not so true, most any VFD will not die from the motor being switched on/off, even though the manufacturers are not usually keen to admit that. The issue is the inrush.

    A 2HP VFD will handle an overload to maybe 150% of a 2HP motor full load current for usually 1 minute or so, and "some" may handle 200% for a couple seconds as a real published rating.

    Problem is, the inrush will be 500% to 700% of full power current. So you need something on the order of a 7.5 HP VFD at least, to be somewhat sure of handling that 2 HP motor inrush from being "dropped across" the output with 60 Hz coming out of the VFD. Better larger.

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    You can bury the VSD and still use the existing controls.

    What you need to do is disconnect all the existing wiring from the controls and hook the motor up to the VFD output directly, possibly except via a mechanical switch to ensure it cannot possibly accidentally start.

    Then find a terminal on the switch that closes for run-forward and another that closes for run-reverse, and wire those up to the appropriate VFD inputs. If you have more switch positions available or buttons, you could experiment with different speed setpoints or jog options.

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