VFD and Motor Help

Hathenbruck said:
That did it!! Runs the 4" wheel like a champ, but the 7" wheel doesn't want to get going. Speed surged a few times, then it stopped. I can't thank you enough for your help. This was so aggravating.
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When you say "then it stopped", is the VFD tripping out? Looks like there is a status LED that will quick flash red for an overload fault. If that's what's happening, the accel rate could be set too fast, or the current limit could be set too low.
 
yeah...the VFD tripped out. I'll play around with the trimpots and see if I can't get this wheel going. Thank you for your time and your help! You guys taking time out to help me with my problems means a lot.
 
With the 7" drive wheel and the 3600 rpm motor you're looking at a tad over 6,000 SFPM belt speed at max. Should not be a problem with power. I use a 3600 rpm 2hp motor and the only way to choke it down even at 50% speed would be to really lean HARD on the grinding. If you've got the speed set really low, say 10% or so then the nature of a VFD will limit the amount of power you've got.

Your video looks pretty slow belt speed - what rpm (or %) are you running there? Did I see the belt start back up after stopping? Are you sure the belt isn't slipping? Anything over 30% or more the blade will slip on magnet before motor will choke down. Normally speaking if it's the motor stalling there will be an error code displayed (or LED) and motor will need resetting to start back up.

I'm not all all familiar with your VFD, but do understand there are jumpers and trim pots that have to be set correctly. I use the cheap simple Chinese VFD drives. Folks talk about the limited torque of a 3600 rpm motor vs 1800 rpm, it's not enough difference you'll ever know it in use.
 
Ken H> said:
With the 7" drive wheel and the 3600 rpm motor you're looking at a tad over 6,000 SFPM belt speed at max. Should not be a problem with power. I use a 3600 rpm 2hp motor and the only way to choke it down even at 50% speed would be to really lean HARD on the grinding. If you've got the speed set really low, say 10% or so then the nature of a VFD will limit the amount of power you've got.

Your video looks pretty slow belt speed - what rpm (or %) are you running there? Did I see the belt start back up after stopping? Are you sure the belt isn't slipping? Anything over 30% or more the blade will slip on magnet before motor will choke down. Normally speaking if it's the motor stalling there will be an error code displayed (or LED) and motor will need resetting to start back up.

I'm not all all familiar with your VFD, but do understand there are jumpers and trim pots that have to be set correctly. I use the cheap simple Chinese VFD drives. Folks talk about the limited torque of a 3600 rpm motor vs 1800 rpm, it's not enough difference you'll ever know it in use.
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In the video, I was running at 100% with the 4" drive wheel. Pretty slow! The problem is that I had the motor wired for high voltage, not low voltage. I wired for low voltage, and now it's got some great power. I had some issues with cutout with the 4" drive wheel, and the status was flashing red/yellow, but not sure if it was fast or slow. I turned down the CL pot and it seemed to fix it. I'm pretty positive that all my issues are just trimpot adjustments, now.

It's good to hear about the torque differences between 1800 and 3600. I know some people make it sound like it's a night and day difference.

Thanks you!!
 
OK, I didn't realize the video was when the motor was still wired for 460VAC (high voltage). That would make a difference for sure. Good luck and enjoy the grinder. I used a 3 step pulley setup for the first couple of years and couldn't understand why anybody "needed" the VFD. I built another grinder with direct drive and VFD - WOW - what a difference. If you've got to buy the motor, no difference in price to speak of. Using a Chinese VFD the cost is less than the pulley, shaft, and bearings to setup a 3 pulley setup.
 
My old motor was a single speed 1800rpm with a 7" drive wheel, so I'm loving this. I ordered a 5" drive wheel, which would give me about another 1000sfpm. That should be plenty fast for me, and not take away too much from the power...in case I might need it. I'll use my old motor for a disc grinder :) Maybe I'll look into a chinese VFD more that.
 
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