Not sure if I've got this wrong ...

[thewoodnerd]

I just wired up my new TECO drive to this 3ph motor. The motor spins and runs at variable speeds as expected. But ...

1) At low frequencies, under 8 hz or so, the motor's motion is noticeably jerky. I can't tell if the shaft is running smoothly or not, but I can feel a definite "pulsing" when my hand is on the body. Is this a normal effect of such a low frequency?

2) The motor seems to take a long time to come up to speed. Not bad, but not what I'm used to on my Powermatic wood lathe which also uses a VFD and 3ph motor. The frequency display on the drive shows the frequency slowly moving up and down whereas on the lathe just shows the target frequency. Is the drive slowly ramping the frequency instead of just producing it straight out? If so, can/should this behavior be changed?

3) If I flip the reverse switch on the lathe, it very quickly slows down and starts going the other way. If it's going slowly enough, the change is almost instantaneous. On this motor, however, if the motor is moving slowly it will slowly stop and then slowly come up to speed in the other direction. If it's initially going at a good clip, it'll slow down and then continue slowly in the same direction. Do I just have the wrong kind of motor for quick reverse?

Any and all help would be greatly appreciated.

[underthetire]

I don't use that brand, but typical you need to set ramp up and decel time constants in the parameters. Some drives have extra torque/voltage settings for low speed.

[thewoodnerd]

I've looked over the user's manual, which is really oriented towards someone who already knows what they're doing

Lots of parameters, no explanation of what they do. I've changed a few things that sounded like acceleration curves, but with no change.

[michaelthomas]

I don't have any experience with that particular drive, either......but I had to fool with the drive on our Onsrud some last year when we were using some really big cutters. It would overload on spin-up. You just have to keep trying, and be diligent about writing down what you already had entered.

There has to be some people on here with Teco experience.

[Al_The_Man]

Is the VFD a variable frequency only or sensorless vector? the latter is the better one.
Accel and especially decel rates, if you set them too short can cause overvoltage due to back EMF, and in some cases an external braking resistor is needed, especially with high inertia motors and/or loads.
It sounds like it drops out of run with when trying to reverse at high rpm?
Al.

[hub]

Not familiar with that VFD but here is my opinion.

1) I think it's how your VFD works at low frequency.. My VFDs are smooth running at low freq. But do you really need to run the motor <8Hz?
2) The acceleration time is too long. Find a setting for the acceleration time.
3) It is the acceleration & deceleration time that makes the reversal delay. Fix 2) and this will be fixed too.

Do you have a link to the VFD manual?

[thewoodnerd]

- The drive is sensorless vector, TECO 7300CV, although apparently it can also run as plain VF.

- pdf manual: http://factorymation.info/acdrives/7300cvmanual.pdf

[thewoodnerd]

Originally Posted by hub But do you really need to run the motor <8Hz?

No, but I'm worried that the pulsing is a symptom of something I've done wrong that's just not noticeable at higher speeds.

[hub]

Ok, check these:

Func 1-02, should be 0000: Enable Reverse Command (probably is since it reversed)

So here are the important ones:
Func 3-02 (Accel Time 1)
Func 3-03 (Decel Time 1)
Func 3-04 (S-Curve 1) S-Curve Acc/Dec # 1 (Seconds)
Func 3-05 (S-Curve 2) S-Curve Acc/Dec # 2(Seconds)
Func 3-06 (Accel Time 2)
Func 3-07 (Decel Time 2)

I didn't find any setting to choose which accel/decel it uses.. So check all of the above.

[thewoodnerd]

OK, I swear I changed these before, but cranking 3-02 & 3-03 down to .01 made start/stop almost instantaneous. It also fixed the reverse from all speeds.

Thanks guys!