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Protection of motors

Post in 'The Pellet Mill - Pellet and Multifuel Stoves' started by GVA, Oct 2, 2006.

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  1. GVA

    GVA Minister of Fire

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    In the industrial control industy we have to protect motors from failing due to overloads undervoltage etc...
    Wouldn't it make sense to protect the auger gearmotor (the one most likely to overloading) from over loads and how would you guy's go about it.......
    I already have a solution but just wondering what everyone else thinks :coolsmirk:

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  2. Homefire

    Homefire New Member

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    I install a themal overload on mine.
  3. GVA

    GVA Minister of Fire

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    But why should you have to install it?
  4. hearthtools

    hearthtools Moderator Emeritus

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    Augermotors are already have thermo overload.
    One of the reasons they go out is the Uneven angle they are mounted in a pellet stove.
  5. drizler

    drizler Minister of Fire

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    Not much chance of that happening in the winter around NY. On the other hand I always unplug it during the summer. Lost the circuit board like that in my brand new Hobart MIG welder a couple years back. I would imagine that if it was an issue where you are that a computer uniterupted power supply would be the best followed by a good power strip. Those power supply battery packs will suck up one hell of a shock before it goes any where.
  6. begreen

    begreen Mooderator Staff Member

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    There's another thread about this. The best protection I can recommend is an uninterruptible power supply which will regulate the voltage to the stove regardless of input variations.
  7. GVA

    GVA Minister of Fire

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    I don't think the gleason avery gearmotor on the harmans are thermally protected, They do also use a jakel motor I believe only on the direct drive units,not sure if they are protected
  8. Homefire

    Homefire New Member

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    Why did you ask ?

    What is your solution?
  9. GVA

    GVA Minister of Fire

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    Well one of my first posts was about how I went through so many gearmotor and actually watching the auger binding (for still an unknown reason) I saw the entire motor mount bend till the chain popped off. It took a while to get the mount straight again. Before this incident I had blown a couple of gearmotor and this one soon followed, the manufacture in 2005 modified the gear that always was breaking on the gearmotor I still have a 2004 in it I suspect that it will shatter the gear again eventually..... My idea came to me while working on a label machine at work.... It has two feed screws that space and align the bottle to the labeling head. It has a clutch on it it's sized to 300 inch pounds which is what the gear,motor is. In case of a jam up it will actually slip until the overload is removed.

    The pellet stove is about 120 inch pounds but unfortunately this is far to much force for the little motor mount to handle.

    I tested out the clutch on my stove and it worked beautifully it was set at 60 inch pounds.
  10. Homefire

    Homefire New Member

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    I see, mine is mounted directky to the auger and it just sort of grinds the pellets or corn until they crush brfore they become jammed.
    I just try to insure the don't drop any little metal cars in the hopper.
  11. Corey

    Corey Minister of Fire

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    IMHO, I would look at why the auger is jamming in the first place. Is it misaligned, too close / too loose of a fit, bad bearings, bent parts, etc.

    The most simple solution I can think of to help prevent a motor burn up during jamming would be the thermal switch or a properly sized fuse/circuit breaker to cut out the motor when too much amperage is drawn by the locked rotor. Something a little more fancy might be a circuit to detect the extra current draw and reverse the motor for several seconds.
  12. GVA

    GVA Minister of Fire

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    Everything has been checked out.
    The dealer said that the noises were normal and said it was just the stove trying to chew through a pellet....
    They must be pretty hard pellets.... Anyway the fact of the matter is the manufacturer of the motors re engineered the motor for the defective gear that kept failing. My only thought could be that the gear was a bit stripped and just happened to line up with the slide plate wide open and allowed the feed throat to over fill and caused the auger and slide plate to bind when it came back to re-engaging with good teeth and then causing the motor to get so overloaded that the motor kept going till the mount got bent and the chain popped off.
    This also tore up those stupid little rubber grommets that help to isolate the feed motor vibration, stretched the chain a bit which also led to the sprockets getting chewed up, all since been replaced.
    Those grommets my dealer did not have any... I ordered my own with a heavier durometer (very nice) the old ones allowed the motor to flex back and forth too much changing the alignment of the sprockets adding to my pains of the gear-motor and whole feed system failing.

    In a nutshell I just would like to know if maybe harman and others can look into better protecting the gear-motor on the chain drive feed systems.

    As far as adding thermal protection or fuses I would think that could void my warranty, but the clutch actually just replaces the drive sprocket on the gear-motor, it's pretty simple I just had to machine a stub adapter shaft and drill some holes in a A type sprocket to mount it to the clutch.

    Do I need it? After so many problems I have peace of mind that until I get a 2005 or newer gear-motor it won't be breaking again.... so far so good....

    Thanks for your input guys :)
  13. drizler

    drizler Minister of Fire

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    is that clutch a generic sort of thing and do you have a pic or url to a pic of one?
  14. GVA

    GVA Minister of Fire

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    Sorry it took so long
    I'll get back to you with the pics I'll have to find the disc the pics are on...
    It's a stock clutch, though you need to specify the style, like shaft to shaft for direct drive or hub style for chain drive.
  15. drizler

    drizler Minister of Fire

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    Yea please do. I just heard one of you guys on another thread mention some sort of overload electronic switch to protect a gearmotor. That is one gottahave for a corn burner as chunks and pieces are just a fact of life. That gear motor issue thing is going to be the next mod I am going to do with my already heavily customized Countryside.
  16. GVA

    GVA Minister of Fire

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    Again sorry Driz for it taking so long.
    Had some computer issues as well as long hours at work..
    Couldn't find the pics so I dug it out of the moving boxes and took some more so here goes..

    Attached Files:

  17. GVA

    GVA Minister of Fire

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    I'd post 2 more pics but I get "unable to recieve your submission at this time" on one
    and wrong file type MIME or something like that.........
    Moderators what could be the problem???????????
  18. drizler

    drizler Minister of Fire

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    I thought there was something more to it but I wasn't going to say anything. Tip my hand of ignorance or gift horse in the mouth. Anyways if you get a chance I sure would like to see the whole setup. No hurry, looks like we are pretty much done burning for the season anyways.............
  19. stoveguy2esw

    stoveguy2esw Minister of Fire

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    you could do that if it is an inverted "dc" motor , unfortuantely an "ac " motor cannot reverse direction without literally "flipping the field" or unbolting the "magnet" and turning it upside down. this would not be feasible in normal operation. best advice i can offer is thus;

    bottom feed stoves: ESW harmon etc... ensure there is no carbon buildup that could affect moving parts driven by these motors

    top feed stoves: Quads, Breckwells, top feed ESw units etc... periodically inspect hopper base for fines and remove before they get to heavy or loaded up this puts a strain on motors.

    top or bottom feed , make a habit of listening to your unit. it will tell you if its distressed, moaning , ot ticking noises or "loading up" noises will be there if there is somthing amiss. if you pay attention you can catch it and correct it before you have to reach for your wallet. stoves will tell you where it hurts , you just have to listen.
  20. tyru007

    tyru007 New Member

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    GVA: I would like to know what slip coupling you are using?

    I'm a pellet stove newbie, but I design and build industrial control systems including conveyance systems for pelletization facilities. 40 to 100 HP conveyor drives but the principals should also apply to small augers in pellet stoves. Typically, we design protection systems from the following:

    Overload - sustained current draw over the full load amp (FLA) rating of the motor for a period of 30 seconds (class 20)
    Ground Fault and Short circuit - circuit breaker designed to open the circuit on a fault to ground or short circuit
    Bearing failure or sieze - high current draw due to bearing failure or high load (still turning) >125% FLA for 5 seconds
    Jam (Locked rotor current) - very high current when the rotor is jammed or seized solid. >180% FLA for 1 second

    Most motors will see a current spike in the first 1/2 second of 5-8X the full load amps of the motor during starting, also called the starting current.

    Looking at the number of posts on this board, auger failure due to siezing or jamming appears quite common. Since all these pellet stoves come with controller boards that turns on/off the auger motors, I dont understand why the manufacturers do not provide a small current transducer on the power wire to the auger to monitor the current draw. These fixed ring transducers cost about $30 (probably less in bulk). The controller could then provide a warning on high sustained current draw (seizure) and an alarm on a jam condition and shut down the stove.

    If you want to make your own, you can buy a current switch with a built in time delay (such as ACSX200-AE-F at automation direct). Mount it in a small metal box with a latching circuit, power led light, alarm led light and reset button. Run you power wires for the auger to the box and then from the box to the controller circuit.
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