I just hooked up a VFD device to get 3-phase in the garage. I have a motor from an old 3-phase grinder that was in bad shape when I got it.
I have cleaned the motor up and repaired some of the wires coming out of it.
The motor came with a Reverse-Off-Forward style switch that I also cleaned up and re-connected. The switch has 6 connection points.
Upon powering the VFD up, I got the following to happen:
1) Switch in OFF position = no motor rotation and no noise or smoke from the motor or VFD
2) Switch in REVERSE position = motor rotating in a CCW direction
3) Switch in FORWARD position = buzzing in the motor but no rotation
Does this suggest to you that I have a problem in the motor or in the switch?
You didn't say if the motor can be wired for high/low voltages. Assuming it can, then miswiring the motor leads can lead to buzzing and not turning. However, either the motor is wired right or it isn't. If it runs strong and correctly in one direction, then I personally would conclude the motor is wired correctly and the switch wiring is at fault.
In cases like this it is always helpful to simplify the problem. You might consider running VFD power directly to the motor, bypassing the switch. If it works, then swap any 2 leads and restart. It should then run in the other direction. If that all works fine then for sure the problem is in your switch wiring.
Hmmm. A good idea if I only knew how. The motor's 6 switch connections come out on one side of the motor and the 3 power connections come out on the other side.
Obviously I should connect the switch wires together in some fashion but I'm not sure which ones should be connected to which.
wrote: (clip) Does this suggest to you that I have a problem in the motor or in the switch? ^^^^^^^^^^^^^^^^^^^ It has to be in the switch. The motor runs normally on one direction. To reverse a three phase motor, you reverse any two leads. To verify this, you could reverse two wires from the switch to the motor, and it should run in the opposite direction. This would absolutely confirm that nothing is wrong with the motor.
Look inside the switch, and you should see some sort of plarity reversing configuration on two of the conductors. My guess is one of them is open.
I recomend you wire the motor to the VFD directly. The VFD will allow you to reverse direction, and will ramp the speed down and up nicely. Disconnecting the motor whilst driven will produce voltage spikes that could destroy your speed controller.
Three phase motors have either three, or six wires out. Three wire motors are not able to run on different voltages. Six wire motors can be wired in Delta, or Star. Don't worry about the names, it just means either the three coils have theiir ends joined end on end (Delta) or one wire from each winding joined together in a centre point which is not connected outside the motor. (Star). Either way you end up with three wires to connect. Smaller (Less than, say, 3kW [4hp]) Motors usually have 230v windings. These will run on
400V wired in star If you are runnning a motor with excessive voltage, it WILL get really hot quite rapidly, and may make smoke, before burnig out. Totally enclosed motors ( no vent slots in the casing) do not smoke much. Loud humming from the motor is a cause for worry - check your wiring, and the motor temperature at frequent intervals, until you have confidence all is well. Good Luck.
I vote for putting the switch in the reverse position, swapping two of the input leads from the VFD, and letting the VFD do all the reversing in the future. As long as the motor runs in one way, the VFD will take care of the rest. You don't want the switch on the loadside of the VFD while it's trying to spin a motor, so just keep it simple and run it the way that works right now. Got nuthin' to lose.
That depends. What direction did you *want* the motor to spin? Reverse and forward are relative terms which depend on your application.
If you want it to go in the other directions, just interchange any two of the three wires -- at the motor, at the switch, or at the VFD.
However -- as others have already said -- you should *not* have a switch between the motor and the VFD -- though it won't hurt anything as long as you don't switch it while the VFD is providing power.
The VFD itself can generate forward or reverse three phase, so you need to get the wires set up to the VFD's "forward" mode turns the motor in the direction which you want.
And -- the VFD can be commanded to go from forward to reverse (and to stop/start) by three wires between the VFD's control terminals and a very light duty switch -- though you could easily run those three wires form the VFD to the original switch (after you remove the power wiring from it), so the original switch could command forward/stop/reverse just as it did before. However, you gain the advantage of having slow start/stop, so the maximum current to the motor will be a lot lower.
You seem to be talking about the motor wiring common in the UK (and apparently in other parts of Europe, as your domain puts you in France).
In the US (and the original poster appears to be in the US, based on *his* domain), dual-voltage motors are typically supplied with nine wires, and are wired either in series wye (star), or in parallel wye. Start out with two idential sets of three windings, connect the start end of one set together and bury it in the motor's housing where you can't get to it.
For low voltage, connect the start end of the other set together and insulate it, then connect the finish end of both sets of windings together to make the terminals for power input.
For high voltage, connect the start of each of the free windings to the finish end of the three which are joined inside the motor housing, and connect the finish end of each of those final windings to the incoming power.
Of course, you need to be careful *which* coils are connected in series or parallel. This is normally handled by numbering the nine available terminals, and presenting a chart on the motor's label to show which connections allow operation at which voltages.
This gives two volages which differ by a factor of two. Common machine tools of a scale which fit in a home shop have choices of 240V or
480V (or slightly scaled down to as far as 220V or 440V depending on the age of the motor.)
Your Delta/Wye choice gives two voltages which differ by a different factor, which I *should* remember, but don't because I don't encounter them often enough.
This difference between European and US wiring standards leads to confusion in newsgroups like this which span both areas.
Anyway -- the following applies to the European motor style, and probably does not apply to the motor which the original poster has, unless it was imported.
The VFD came with a manual with over 100 pages of "don't do this" and "don't do that". I probably missed the part that said it could control the direction of rotation.
I also missed the part about "Disconnecting the motor whilst driven ...". Thanks for filling me in.
I'm off to remove the 3-way switch from the machine.
Thanks for yoru help.
Gary
PS I work for a multinational company. Its hard to say what prompted the European link but I live and work in Los Angeles. The motor is from a KO Lee tool & cutter grinder. The motor has a GE label on it.
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