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3 phase gear motor, torque, VDF converter 115v, brake on hoist

3 phase gear motor, torque, VDF converter 115v, brake on hoist

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  #1  
Old 12-03-11, 10:33 AM
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Question 3 phase gear motor, torque, VDF converter 115v, brake on hoist

Iíve built a light weight frame for a hoist which only needs to lift around 500 lbs. The cable spool needs to hold 250í of 3/16 cable that can lift a submersible well pumps from that depth. The hoist will also be used to develop the well and without going into great detail about this, Iíll just say I need the spool to be variable speed with a holding brake - RPMS from 0-100. I could do all this with hydraulics which I know more about but I would like to explore the idea of a 3 phase gear motor with a constant brake, reduction to 20:1 gear box and a variable frequency drive.
I need help in knowing what horsepower motor (also torque) that Iím looking for and what type of brake would be sufficient to hold the load.
Also, I need an adequate VFD converter from 1 phase 115 v to 3 phase 208-230 that can work with the brake too. Some VFDís canít be used above 3,000í altitude and Iíll be using this at 7,200í (a Nema 4 enclosure maybe appropriate because Iíll be using it outside) I would love to have speed control by a foot pedal if possible to keep my hands free.
And to top all this off, I need the motor, gearbox and VFD their combined weigh to be 40 lbs. or less. Now if there is a simpler way to do this, like a brushless motor with speed control or something, let me know.
It needs to be 115 volt system with constant torque with the ability to hold the cable and load in place. Anyone up for the challenge in helping me, I would appreciate it.
 
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  #2  
Old 12-03-11, 11:00 AM
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It needs to be 115 volt system
A 115v 3 phase motor would be a rare bird indeed. Sounds more like you have single phase 120v power. Do you really have 3 phase power? Were you planing to use a converter?
 
  #3  
Old 12-03-11, 11:37 AM
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Sounds like what an elevator drive in a high-rise building would do!

I've not seen these for years, but the last I saw was a big DC motor. And they had a big AC to DC motor generator to make the DC.

Might try your local elevator companies?

Also I have seen coal mining scoop machines (excavators?) which are the size of a house and use a huge electric motor with electric braking. The whole machine is electric.

Here is one of those manufacturers...
Electric Rope Shovels | P&H Mining Equipment
 
  #4  
Old 12-03-11, 01:11 PM
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Finding a VFD with a 120 volt single phase input that has an output of more than one horsepower will be a challenge. The rest sounds at least do-able but I think I would be tempted to go with the hydraulic. This sounds like a fairly high duty cycle for a VFD.
 
  #5  
Old 12-03-11, 02:25 PM
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Wink VFD 115 v

Originally Posted by Furd View Post
Finding a VFD with a 120 volt single phase input that has an output of more than one horsepower will be a challenge. The rest sounds at least do-able but I think I would be tempted to go with the hydraulic. This sounds like a fairly high duty cycle for a VFD.
You're right, the largest VFD single phase (115 v is how they designated it) to 3 phase (208 v -230 v) that I could find is 1.5 horsepower, but the question is how much hp do I need for lifting only a small amount (500 lbs) 1/4, 1/2, 1 hp ??? and VFD's come with all kinds of features I don't need, but I do need the braking component.
And remember I'm trying to keep this as light as possible.
Someone smarter than me must know the torque on a spool that can reel a cable in with max 500 lb load. I can't imagine that it's that much and considering I'm reducing it 1:20- should significantly increase the torque. The 3 phase motor will be standard 1750 rpms
 
  #6  
Old 12-03-11, 03:25 PM
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I once made a hoist that easily moved 250 pounds with a 1/2 horsepower motor going through a gearbox but I don't remember what the ratio was, maybe it was 30:1. I never checked the amperage draw on the motor so I don't know how heavily load it was either. I think the gearbox would have prevented movement when the motor was off but I also added a mechanical brake between the motor and the gearbox that was electrically actuated. I do think that your 40 pound weight limit will be VERY difficult to achieve.

Gearbox was similar to this: Reducer, Speed, 44 RPM - Speed Reducers - Speed Reducers - 2Z933 : Grainger Industrial Supply

And the brake was mounted between the motor and the gearbox. Similar to: Brake, Motor, 3 Ft Lb - Brakes and Clutches - Brakes and Clutches - 6K233 : Grainger Industrial Supply

That's about all I have to offer.
 
  #7  
Old 12-03-11, 06:10 PM
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Smile In the ball park

Furd, this information is very encouraging because I now know it can be done with 120 v power - in other words, the motor will be 1 hp or less because I didn't have any idea how much horsepower I would need.
The next question for someone you knows how to calculate this is how small of a motor will do the job, which will tell me something about the VFD I get too. I appreciate your responses, we're on the right track.
And a 3 lb brake will hold the load? I see gear motors on Ebay with brakes with 3 lb torque (this seems to be pretty standard)
 
  #8  
Old 12-04-11, 08:48 PM
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so anyone know the torque needed to turn a spool with 500 lb load?
Originally Posted by cat-on-edge View Post
Iíve built a light weight frame for a hoist which only needs to lift around 500 lbs. The cable spool needs to hold 250í of 3/16 cable that can lift a submersible well pumps from that depth. The hoist will also be used to develop the well and without going into great detail about this, Iíll just say I need the spool to be variable speed with a holding brake - RPMS from 0-100. I could do all this with hydraulics which I know more about but I would like to explore the idea of a 3 phase gear motor with a constant brake, reduction to 20:1 gear box and a variable frequency drive.
I need help in knowing what horsepower motor (also torque) that Iím looking for and what type of brake would be sufficient to hold the load.
Also, I need an adequate VFD converter from 1 phase 115 v to 3 phase 208-230 that can work with the brake too. Some VFDís canít be used above 3,000í altitude and Iíll be using this at 7,200í (a Nema 4 enclosure maybe appropriate because Iíll be using it outside) I would love to have speed control by a foot pedal if possible to keep my hands free.
And to top all this off, I need the motor, gearbox and VFD their combined weigh to be 40 lbs. or less. Now if there is a simpler way to do this, like a brushless motor with speed control or something, let me know.
It needs to be 115 volt system with constant torque with the ability to hold the cable and load in place. Anyone up for the challenge in helping me, I would appreciate it.
 
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