Bridgeport Motor Issue (Video)

[Ceej0103]

I'd start by verifying power supply from vfd

I addressed this is my post above; to test it further I'll hook it up to another motor tomorrow.

 

[Ceej0103]

what type of VFD are we playing with?
can you post a picture as wired on both ends? ( the VFD and Motor wiring)

the settings could be off, the carrier frequency sounds high

It's a cheapo from Amazon. I'll post some more pictures tomorrow. The way that it's wired has worked fine on the machine for months. In the video, I was running the motor off a different drive (KBAC) to see if I could isolate the issue to the VFD.

 

[Ceej0103]

This'll be three phase, so no caps or switch on this one. I was thinking start basic by measuring resistance of the windings, then work back from there. If you've got even resistance between pairs, you can be fairly confident it's time to look at the VFD assuming it's not just a connection issue. I've not yet tried putting a meter on a VFD to measure output voltage. I have a feeling the PWM output will throw a digital into a fit...

Another motor to prove the VFD on is a great shout if available. It behaves like a motor that's either being run way under volt or with a phase or two disconnected, though the screaming can also be caused by having wiring incorrect on certain types of motor (two speed from personal experience), which is also accompanied by rapid rotor heating.

When I put a meter on the output side of the VFD, it was giving me some really wonky readings. The first pole was almost always 120v, but the second and third pole were all over the place. Is that due to PWM?

 

[ttabbal]

I suspect the meter doesn't like the PWM. If you have a scope, that would work, but if swapping to another motor works then it's probably the motor that has an issue. Did you test resistance of the windings? With the VFD disconnected, each winding should be similar resistance.

 

[Ceej0103]

I suspect the meter doesn't like the PWM. If you have a scope, that would work, but if swapping to another motor works then it's probably the motor that has an issue. Did you test resistance of the windings? With the VFD disconnected, each winding should be similar resistance.

I did not. When performing that test is it necessary to de-couple the wires? The motor has 9 separate wires labeled 1-9 if I recall correctly. I think 6-5-4 are connected together and 9-1, 8-2, and 7-3. What number gets tested against what other number during the resistance test?

 

[metric_taper]

A quality designed VFD would error out. I'm in agreement with others that it's the VFD.
I heard the noise from a switch in the video, is this wired to the control input discretes of the VFD, or are you switching the the motor connections between the VFD and motor?
If so, you know that most likely blew up the VFD output drive transistors.
Much more information needed, like a photo of the whole system, and a wiring diagram.

 

[Ceej0103]

A quality designed VFD would error out. I'm in agreement with others that it's the VFD.
I heard the noise from a switch in the video, is this wired to the control input discretes of the VFD, or are you switching the the motor connections between the VFD and motor?
If so, you know that most likely blew up the VFD output drive transistors.
Much more information needed, like a photo of the whole system, and a wiring diagram.

Sorry, not completely sure what you're asking. Wiring goes like this: Panel to VFD Ground, Hot, Hot -> 3 VFD Poles out to the Bridgeport's Drum Switch - > Drum Switch to the motor. I haven't pulled it all apart, but it's wired low voltage so I'm fairly certain that means motor wires 6 - 5 - 4 are bundled together with a wire nut. 9 - 1, 8 - 2, and 7 - 3 each get connected to a wire coming from the drum switch, which correspond to one of the poles on the VFD.

To operate, I turn the VFD on at 60hz and then use the drum switch to operate the machine. Will this ruin a VFD? Check my next post, VFD is good.

 

[metric_taper]

Sorry, not completely sure what you're asking. Wiring goes like this: Panel to VFD Ground, Hot, Hot -> 3 VFD Poles out to the Bridgeport's Drum Switch - > Drum Switch to the motor. I haven't pulled it all apart, but it's wired low voltage so I'm fairly certain that means motor wires 6 - 5 - 4 are bundled together with a wire nut. 9 - 1, 8 - 2, and 7 - 3 each get connected to a wire coming from the drum switch, which correspond to one of the poles on the VFD.

To operate, I turn the VFD on at 60hz and then use the drum switch to operate the machine. Will this ruin a VFD? Check my next post, VFD is good.

I think you are using the drum switch between the VFD and the motor, and that is a HUGE NEVER DO for a VFD. You always hard wire the VFD to the motor. Switching while running causes huge voltage spikes, these exceed the transistor break down voltage. I'm guessing you blew up your VFD. And it should have error'd out on this. You may have been doing this for a long time, but I'm believing this finally failed.

 

[Ceej0103]

Well I knew I couldn't sleep unless I tested it on a different motor. Here's the VFD running on my belt grinder. This is the same way I wire it for the Bridgeport motor. From left to right on the VFD, the first post is ground, second is L1, third is L2. On the right side they're labeled like U V W or something like that, but those are my lines out to the 3 phase motor. Those get connected to whatever set of lines I decide on the motor side, and a pair can be switched if I need to switch direction of the motor. I think this is rather common.

Also, I've eliminated the drum switch from the equation and wired directly to the motor. No difference. I'm fairly certain we can rule out the VFD and start looking at the motor.

 

[metric_taper]

Well I knew I couldn't sleep unless I tested it on a different motor. Here's the VFD running on my belt grinder. This is the same way I wire it for the Bridgeport motor. From left to right on the VFD, the first post is ground, second is L1, third is L2. On the right side they're labeled like U V W or something like that, but those are my lines out to the 3 phase motor. Those get connected to whatever set of lines I decide on the motor side, and a pair can be switched if I need to switch direction of the motor. I think this is rather common.

Also, I've eliminated the drum switch from the equation and wired directly to the motor. No difference. I'm fairly certain we can rule out the VFD and start looking at the motor.

OK, have you used an ohm meter to motor ground for each of the 3 leads? That's the other issue with large voltage spikes they can break through the winding insulation and produce a short connection. Also look for any frayed old motor leads or your splices and verify they have not gone to ground.