raising torque of a motor w/ PFLX70

[unsaint32]

We have a a following motor and drive for a wrapping film feeder/roller.
VFDowerflex 70 EC-E AC drive
Motor: 460V, 2.1A, 60Hz, 1 hp, 3 phase, induction motor.
PLC: Contrllogix 1751 (w/ RSLogix 5000)

As the roller pulls the film off its spool, the motor torque increases for a second or so. But at one point, the rollers just did not turn to feed the film. So, we raised the value of parameter 69 of PFLX70 (Start/Acc boost) from 12.7 to 50 VAC. Then the rollers worked after that. But it also raised the motor current level to about 3amps (the motor was rated at 2.1). But it was only for less than a second, and each process cycle takes about 2 minutes. So, we can handle that.

My question is, was there a better way to increase the torque value than raising the start boost value? Of course we can get a bigger motor and fix any mechanical issues; bearing, belt, etc. But my question is strictly for adjusting PFLX parameter values.

Thanks.

 

[DickDV]

If you are able to raise the starting voltage as you describe, then you are operating the motor in V/Hz control mode. I believe the PF70 is capable of sensorless vector control and by choosing that and reprogramming the drive, you could expect to get much better torque management at very low speeds.

There are a couple of Allen Bradley guys on this BBS who can advise you with precision on how to get this done. JRAEF, are you within hearing distance on this?