# So educate me on the difference between soft start and a VFD



## mlappin (Jun 25, 2009)

Finally got back to picking corn today, knocked out 50 acres no problem then the pit drive quit. Reeves 5HP variable speed motodrive double gear reduction series 222, stripped the low speed pinion gear. Had a spare that used to be on the pit but developed a leak, took it apart, low speed pinion isn't stripped but is close to being junk as well. Looked up the install manual as I thought maybe the lateral load was too much and causing some deflection on the output shaft, drive the 15" pit auger with a double 60 roller chain. Only thing the manual said was to make sure if using pulleys, gears or sprockets that they were in alignment so I ruled excessive lateral load out. What I think is the problem is I have a EZ switch mounted in the end of the auger trough right where it dumps into the leg, if the corns wet or just doesn't flow well it backs up enough and trips the EZ switch then after a 10 second delay it restarts the pit and this is what I think is eating the pinions. When it restarts it gets the full torque and speed of the motor while also being full of wet corn.

So my thought is getting either a soft start motor starter or using a VFD and having it ramp up to full speed slowly to reduce startup load on the internal gear train of the motodrive.

So the question is this, which is better for this application? A soft start motor starter or a VFD set up to ramp the motor speed up over 10-20 seconds?

Picture of what used to be a low speed pinion. It;s somewhat misleading but I did find a few pieces of teeth i the bottom of the drive, so it has snapped a few clean off before eating them, the other pinion while not chewed up as bad does have teeth missing as well.


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## Bonfire (Oct 21, 2012)

I would install a VFD. Price of a 5HP VFD would be what, $3-400? You could program more precisely what kind of voltage and frequency you want. How's the motor wired? 3ph delta 460?


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## mlappin (Jun 25, 2009)

Bonfire said:


> I would install a VFD. Price of a 5HP VFD would be what, $3-400? You could program more precisely what kind of voltage and frequency you want. How's the motor wired? 3ph delta 460?


3ph 240 delta.

460 and 480 scare me.

Would also have to replace a lot of motor contactors and relays that have 240 volt coils not to mention find transformers for several other applications that have 240 only motors and only 240 volt motors are available for them.

I do anything to upgrade service and it will be either another 200 amp service or upgrade the main box to 400 amp service.


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## rjmoses (Apr 4, 2010)

If I understand your problem correctly, neither would be a solution because you're not reducing the load.

If the problem is the "shock" or load at start up, a solution might be to install a slip clutch. Another thought is make up some kind of "throttling gate" that would slow the flow down when handling wetter grain so that its not tripping out.

Just thinking....

Ralph


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## Mike120 (May 4, 2009)

mlappin said:


> What I think is the problem is I have a EZ switch mounted in the end of the auger trough right where it dumps into the leg, if the corns wet or just doesn't flow well it backs up enough and trips the EZ switch then after a 10 second delay it restarts the pit and this is what I think is eating the pinions. When it restarts it gets the full torque and speed of the motor while also being full of wet corn.


I suspect you're right. I'm assuming you're planning to replace the Motodrive with the drop-in INNOVAdrive unit with a VFD. A VFD will give you better control. BUT, be aware that a VFD can introduce harmonics into your electrical system that can cause electrical gremlins to pop up elsewhere. A small 5 hp motor shouldn't cause very much, but if you go that way, make sure it's wired and grounded correctly so you don't get a bunch of RFI or EMI from it. That can be just as bad and mess with your timing restart circuit.

I assume your EZ switch is open for positive flow, closes when flow stops, and triggers the timing on the restart circuit. 10 seconds might be too long and allowing too much buildup. I'd suggest you try cutting the delay in half, looking for other binding points downstream from the unit and put in a shear connector to protect the gearbox. Just my 2¢.


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## dubltrubl (Jul 19, 2010)

While I'm no electrical guy, but we do use both in our industry, and I'd opt for the VFD. A soft start is just that, it slowly applies what the motor needs during the start cycle which can be modified at the uses discretion provided the controls are present. A VFD will adjust load needs as conditions change if the proper controls and programming are present. We also have installed multilin relays on most of our applications that will only allow 3 starts within a specified timeframe, then it goes to a cool-down mode so you won't fry the motor. Just my $.02 and worth exactly what you paid for it! 

Steve


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## mlappin (Jun 25, 2009)

Uh duh, and I did smack myself in the forehead when this came to mind. If I go with a VFD I can set it so the EZswitch closes a circuit and tells the VFD to go to 50% instead of running at a 100%.

Already have the timing circuit as well.

I'm looking at using the VFD set at 100% all the time, but with it's built in overload protection I can take the motor starter/overload clear out of the circuit, will leave the moto drive in as I need the gear reduction, most of the time we unload between 50 and 70 RPM on the pit auger. The motodrive also already has the electric speed change on it so we can change auger speeds from in the control room.

Ground isn't a problem, I have two ten foot ground rods at the pit, also buried 50 foot of bare double ought cable around the perimeter of the pit before backfilling.

If it never stops while corn is still in the pit, then the shock of a sudden restart should be eliminated.


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## mlappin (Jun 25, 2009)

Motion industries just got back to me, looks like the motodrives will be hitting the scrap barrel, $2000 for just the pinion shaft with a lead time of 3-4 weeks.

I want to get done picking corn this year.


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## mlappin (Jun 25, 2009)

Have a size 4 shaft mount gear reducer in the shop now, original shaft is too short, new shaft is being machined right now, I didn't have the proper endmill to cut a 5/8's key way, I also don't have a jig to properly drill the cross holes ninety degrees from one another, but the welding shop in town does so they are handling it.

Went with a ten horse motor to drive it as if it's running at half speed a five won't have 5hp.

May have to break the chop saw out as we may have to notch the pit wall at the drive end as space is at a premium.


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## mlappin (Jun 25, 2009)

Auger and trough is back in the hole, motor is mounted, VFD is mounted and mostly wired, auger and pit was still clear full of corn that has sat since Wednesday, set it to start with a ten second ramp up, started out at 30 hertz as the set speed, powered right up and ran no problems without even approaching max amps, original tachometer in the panel also worked on the first try even though I had to fab up something else for it to read off. Need to get the terminal strip wired now in the VFD so all the original buttons in the panel work. Start/Stop, Fast/Slow, the automatic start/stop in the pit and full boot sensors need wired in yet.


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## mlappin (Jun 25, 2009)

Didi have to notch the wall btw, would have fit but impossible to change belts without.

Couldn't go with the ramp down on full boot. Still on/off as the VFD I have only has three digital inputs, close a contact to run. open to stop is one input, speed up and slow down are the other two. I'm betting though with the gentle ramp up I won't have any problems. Been using it and set the VFD to display motor load, haven't seen it over fifty percent yet even on start up with a full auger and pit.


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## mlappin (Jun 25, 2009)

Picked fifty three acres today in a little over 8 hours, wet bin full, trucks full, cart has a dab in it, new drive worked flawless all day. Need to get a new CT transformer though so the panel meter will agree with what the VFD says for amperage. Panel meter is much easier to read walking by.

Couple of my friends have been helping with harvest since they are both laid off, both are operating engineers with previous farm experience so pretty damn good help, if we could have had em a month ago we'd been done.

Took awhile to convince the one to push the new drive harder as he wasn't coming close to keeping up, once Dad got home from taking Grandma to church he picked while I unloaded trucks and the buddy did the driving. Works much better that way, i can keep the dryer adjusted, mix feed, get the next bin ready, etc all while a truck is unloading.


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## haybaler101 (Nov 30, 2008)

mlappin said:


> Picked fifty three acres today in a little over 8 hours, wet bin full, trucks full, cart has a dab in it, new drive worked flawless all day. Need to get a new CT transformer though so the panel meter will agree with what the VFD says for amperage. Panel meter is much easier to read walking by.
> 
> Couple of my friends have been helping with harvest since they are both laid off, both are operating engineers with previous farm experience so pretty damn good help, if we could have had em a month ago we'd been done.
> Took awhile to convince the one to push the new drive harder as he wasn't coming close to keeping up, once Dad got home from taking Grandma to church he picked while I unloaded trucks and the buddy did the driving. Works much better that way, i can keep the dryer adjusted, mix feed, get the next bin ready, etc all while a truck is unloading.


Keep hammering away, Marty. I don't think I would survive mentally picking corn into mid December. I get a little edgy once Halloween rolls around and we are not done. Last time we took a combine to the field in December on our own crop was probably about 1986. I think I was in jr. High school.


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## mlappin (Jun 25, 2009)

haybaler101 said:


> Keep hammering away, Marty. I don't think I would survive mentally picking corn into mid December. I get a little edgy once Halloween rolls around and we are not done. Last time we took a combine to the field in December on our own crop was probably about 1986. I think I was in jr. High school.


It's not uncommon at all up here that if you have any acreage that your still picking corn into December, seen one guy still cutting beans yesterday. The beans part is a little unusual but not unheard of, we still have 16 acres of beans left on the muck, gonna have to freeze hard for those, just wet enough on top that the sickle bar scoops muck up without even attempting to float on it, been like that for the last month, all the water in the hills around it seep out the sides and come up in the muck and it's not like it hasn't been just a wee bit wet up here. Have just a tad less than 180 acres to go, if the dryer can keep up should be able to knock out 50 a day, on the half mile rows yesterday picking 8 would get you a full hopper by the other end of the field, a good cart operator is imperative.

Earliest I can remember ever getting done was 2010 when the wife had her open heart surgery. Dad and the help plugged away at it while we were at St. Vincents in Indianapolis. Her surgery was November 5th, had her home November 10th, personally took care of her a few days then about the 12th went out and unloaded trucks while Dad and the help finished picking mine, between loads would come in and check on her. Think we had everything put away by the 16th of November.

Might have picked up some more ground in a few years, already have the plow on the truck so took it down and back bladed the shoulder of the road where the trucks sank in and a bad spot in the lane, guy that owns the property next to mine was looking at his, BTO that farms it mudded everything up including the owners drive and the road. Got to talking and he liked the fact that not only didn't we mud everything up but I was fixing a few spots that he didn't even notice. Said he had a year left on the lease with the other guy so I gave em my card.


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## mlappin (Jun 25, 2009)

Mike120 said:


> I suspect you're right. I'm assuming you're planning to replace the Motodrive with the drop-in INNOVAdrive unit with a VFD. A VFD will give you better control. BUT, be aware that a VFD can introduce harmonics into your electrical system that can cause electrical gremlins to pop up elsewhere. A small 5 hp motor shouldn't cause very much, but if you go that way, make sure it's wired and grounded correctly so you don't get a bunch of RFI or EMI from it. That can be just as bad and mess with your timing restart circuit.


Wrapped the leads going to and coming from the VFD with the ground wire, not sure how well it shields it but seemed like a good ideal at the time.

Haven't noticed any timer anomalies since installing it. The only one that is used normally would be the sensor in the pit that starts and stops it, have a 20 second delay on that so the pit empties after the corn falls away from the sensor. Tapped into the original circuit that powered the coil on the motor starter and used that lead to close a relay which starts the VFD, relay opens, VFD stops.


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## mlappin (Jun 25, 2009)




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## mlappin (Jun 25, 2009)

Have gotten everything covered over the years and just keep on drying right thru the rain. Bin sheets over this blower came from the first grain bin this farm ever had, Grandfather put up a 18 foot by 6 ring in the late fifties or early sixties, really thought he had something then. Would do his heart good to see it's still useful for something instead of scrap.


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## Gearclash (Nov 25, 2010)

VFDs are pretty handy, and capable of doing a lot of things with a motor. Had a crash course on how they work this summer when we put one on a sand screw to slow down a 15hp 3ph motor.

Looking at the pics of that failed reduction unit, I'm thinking that there was not enough metal/too much load to begin with. I think a soft start or VFD would have only delayed the inevitable a little. IMO


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## mlappin (Jun 25, 2009)

Gearclash said:


> Looking at the pics of that failed reduction unit, I'm thinking that there was not enough metal/too much load to begin with. I think a soft start or VFD would have only delayed the inevitable a little. IMO


Other thing as well, these were used, I bought em at a scrapyard for a hundred bucks a piece, not sure what they were used for in their previous life.

Suppose it could be too much load, never had a problem with the 5hp motor though coming close to tripping the overloads.


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