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Setting up a VFD to unknown motor

DennisPotter

Plastic
Joined
Jan 16, 2024
Hello, I am having A LOT of trouble getting a VFD working with a motor. I have no experience with VFDs but I have 20+ years of general workshop knowledge. The motor has no documentation or information except for “110V 1.2KW 2500RPM 21.04” I do not know what 12.04 means, perhaps the manufacture date? Motors has 3 wires + 1 ground wire.

I have looked up various things such as https://calculator.academy/hz-to-rpm-calculator/
So the motor should be around 62hz? When I set it to 110v and 60 or 62 hz it over currents immediately. It over current stops on a lot of settings I have tried.

When I set the VFD F009 to 380v and 165hz for F003, F004 and F005, the motor barely works. It over currents half the time and can not take any load. Trying to brute force changing the settings to something else that might work has failed, I have tried many different things. Tried changing F010 to a lot of different settings as well.

We are using the RATTMMOTOR 1.5KW VFD from Amazon. https://www.amazon.com/dp/B09WJV3PM7?ref=ppx_yo2ov_dt_b_product_details&th=1

Any help would be greatly appreciated. Let me know if more information or pictures are needed.
 

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if that is 3 phase would.t the voltage be around 64v per phase?
I would be really surprised to see a 3 phase 110 motor.

edit . I mean the supply side coming from the VFD.
 
Anything special or unique about the motor, because Id say to round file that motor and get one that will work with a typical vfd. I highly doubt that vfd will run that motor no matter how you set it. Its just pretty far outside the range of typical 3ph motors.
 
.3 Ohm between all 3 wires.
wires 1-2=.3?
wires 1-3=.3?
wires 2-3=.3?

Wires 1-gnd=?
Wires 2-gnd=?
Wires 3-gnd=?

Also describe what wires you have connected on the motor to what terminals on the vfd? In the pic you attached it appears you have wrong connections but that may just be the angle of the picture.
 
wires 1-2=.3?
wires 1-3=.3?
wires 2-3=.3?

Wires 1-gnd=?
Wires 2-gnd=?
Wires 3-gnd=?

Also describe what wires you have connected on the motor to what terminals on the vfd? In the pic you attached it appears you have wrong connections but that may just be the angle of the picture.
Good catch, also an amp meter on the leads while it "tries" to run may help see whats going on.
 
wires 1-2=.3?
wires 1-3=.3?
wires 2-3=.3?

Wires 1-gnd=?
Wires 2-gnd=?
Wires 3-gnd=?

Also describe what wires you have connected on the motor to what terminals on the vfd? In the pic you attached it appears you have wrong connections but that may just be the angle of the picture.
The 3 wires are connected to the 3 available 3 phase motor connections, U V W.

wires 1-2=.5
wires 1-3=.5
wires 2-3=.5

Wires 1-gnd= OL
Wires 2-gnd= OL
Wires 3-gnd= OL

 

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Ummm. you need to ohm the motor while disconnected from the drive.

Also describe what wires you have connected on the motor to what terminals on the vfd? In the pic you attached it appears you have wrong connections but that may just be the angle of the picture.
 
62 hertz corresponds to a 3 pole motor. You can't have an odd number of poles. Your option is 2, 4, 6, or 8.

What is the intended purpose of the motor and what is it connected to?

If it's from something like a variable speed pump I'd expect it to be a 4 pole motor run at 85hz, for a synchronous speed of 2550 RPM. This is economical because they are basically using a 60hz motor and getting some extra performance out of it.

So I expect the motor to be around 1.3 Hertz per Volt. Try giving it 39V at 30 Hz and measure the motor current, then measure shaft RPM to check pole count.
 
Ummm. you need to ohm the motor while disconnected from the drive.

Also describe what wires you have connected on the motor to what terminals on the vfd? In the pic you attached it appears you have wrong connections but that may just be the angle of the picture.
The only 3 available connections. U V W.
20240116_144912.jpg

 
Ok so this is just a basic 1 pole pair induction motor? Have you tried this motor with anything else? Any idea what amperage you are hitting before it overloads? Have you metered the voltage from the VFD going to the motor? Are you running single phase into the VFD or 3 Phase? I know you said the motor was 3 phase, but you never did say what you was supplying it with. In your first picture The L/N terminals do not look like there is anything hooked up to them. I thought that was the supply side and UVW was output to the motor. I also can not tell if you have the PE terminal grounded from the picture.
 
Ok so this is just a basic 1 pole pair induction motor? Have you tried this motor with anything else? Any idea what amperage you are hitting before it overloads? Have you metered the voltage from the VFD going to the motor? Are you running single phase into the VFD or 3 Phase? I know you said the motor was 3 phase, but you never did say what you was supplying it with. In your first picture The L/N terminals do not look like there is anything hooked up to them. I thought that was the supply side and UVW was output to the motor. I also can not tell if you have the PE terminal grounded from the picture.
The L/N are power input for the VFD. 120 Single phase in. https://www.amazon.com/dp/B09VXH18J8?ref=ppx_yo2ov_dt_b_product_details&th=1
UVW is output of the VFD going to the motor.
Based on the wire count, I am assume the motor is 3 phase.
 
Are you sure that's an induction motor not a permanent magnet motor? It looks kinda special.

To see if its a permanent magnet motor disconnect the motor leads from the drive and connect an ac voltmeter on the motor leads and rotate the shaft. If you have voltage while rotating its a permanent magnet motor.

It could also be a servo motor. Then all bets are off. I don't work on servo motors. Had one seriously kick my butt once though, threw it in the garbage and bought a high performance induction motor to replace it. Drive had failed and no matter what we did it would not run with a new drive (tried 3 different brand drives - 75 hp) - same symptoms as yours. It was all due to magnetizing currents - someone had modified the original drive for it to work with the motor and we could not figure it out.
 
And that's such a cheap drive all bets are off. Did you read the reviews? - someone had very similar problems.

And drives are sized in amps. Can't find an amp rating in the listing anywhere which is a red flag. Might have missed it though.

But that is a real POS drive.........
 
Are you sure that's an induction motor not a permanent magnet motor? It looks kinda special.

To see if its a permanent magnet motor disconnect the motor leads from the drive and connect an ac voltmeter on the motor leads and rotate the shaft. If you have voltage while rotating its a permanent magnet motor.

It could also be a servo motor. Then all bets are off. I don't work on servo motors. Had one seriously kick my butt once though, threw it in the garbage and bought a high performance induction motor to replace it. Drive had failed and no matter what we did it would not run with a new drive (tried 3 different brand drives - 75 hp) - same symptoms as yours. It was all due to magnetizing currents - someone had modified the original drive for it to work with the motor and we could not figure it out.
We get voltage. Its AC. So this means it is a permanent magnet motor? Can it still work with the VFD?
 
So I am leaning towards it being a PM motor. Is it hard to spin? Try spinning it a little faster just in one direction. Voltage should go up.

Another test is short the motor leads together. If it gets hard to spin the shaft (or near impossible) with the leads shorted together it would basically confirm a PM motor.

That drive will not run a PM motor. That is commented on on the reviews of the drive. The concept is the same, but takes additional programming to run a PM motor on a VFD.
 








 
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