# Rapid Stop/Start VFD



## CyberKnight (Sep 3, 2013)

I built a machine years ago that did alot of cycling. It would really fowl me up with motor getting to speed. I ended up running the motor at what speed i needed and put a clutch/break on it. That way my motor was at my speed and torque and the clutch/break would engage and disengage when needed. It was hooked into a plc for all the control and worked real well. I was straightening and cutting .091 steel wire and forming a bump in the middle all in one shot for calender hangers. It could do 100 /MIN. It could go faster but that was a comfortable speed for our wire payoff. 
Just an idea for ya.
I have had problems with VFd's on cycles with our spoolers for wire. Most of those where stopping the spool inertia (1000 lbs) running at 1500 feet /min. I went to dc regen drives on most of them though.


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## KennyW (Aug 31, 2013)

What is "rapid cycling?" 10 times a minute? 60? 300?

The load is accelerated with torque. You can easily just size a drive that is cable of producing more continuous and instantaneous torque than the motor can supply. At that point the motor is the limiting factor. Drives in that size range are fairly cheap to oversize. 

That being said, like the last guy mentioned, at some point accelerating and decelerating an AC motor over and over again rapidly stops making sense.


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## GEORGE D (Apr 2, 2009)

KennyW said:


> What is "rapid cycling?" 10 times a minute? 60? 300? The load is accelerated with torque. You can easily just size a drive that is cable of producing more continuous and instantaneous torque than the motor can supply. At that point the motor is the limiting factor. Drives in that size range are fairly cheap to oversize. That being said, like the last guy mentioned, at some point accelerating and decelerating an AC motor over and over again rapidly stops making sense.


If I had to guess the fastest would be around 30-40 per minute. What about DC motors?


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## oliquir (Jan 13, 2011)

servo motors or steppers motors would be the best for a small application like that. with any standard vfd accel/decel speed is not made to be under a second generally
just automationdirect for servo or stepper motors kit


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## just the cowboy (Sep 4, 2013)

I'm using a automation direct stepper and cycle it 42x/min about 8-12 rev per cycle. I used the DL05 for about $120 and it comes with software and examples that are easy to follow.
Good luck


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