Dead hand drier autopsy - motor discussion
Good day folks. A few days ago I had the misfortune to be assigned a hand drier, the vertical type with a slot at the top where you insert your hands and a jet of air on either side blasts away the water. This thing was a nightmare to work on and it's stuff like this that makes me hate my job: very dirty, disgusting ! They didn't even have the courtesy to let it dry before plopping it on my desk....dirty water dripping out of it, mixed with bits of dust, hairs and dirt, limescale everywhere, a pungent moisture smell....horrible experience ! The type of thing you would only give to a greenhorn to work on when you don't feel like doing dirty work...most annoying ! Adding to the frustration was that many of the screws were rusty and stuck in place, so just opening up the thing was not enjoyable in the slightest...
Getting past the ugly nature of the job, the actual problem came down to the motor itself which is far past f***ed (see the picture): moisture got sucked up through the bottom, into the whole machine, causing many of the metal parts to rust, including the impeller blades and part of the motor housing as you can see. The expansion of the rust actually caused the impeller to weld itself to the inside lip of the cover there ! I have no idea how it could've possibly ended up SO bad inside - you wouldn't think leftover water on hands can do this sort of damage, especially since it's (SHOULD BE !) designed to be immune to moisture...it's like they left it out in the rain on purpose just to screw with me...
It's also one of the most overkill and over engineered things I've ever seen...just look at that control board ! Was this really necessary ? It's a hand drier - you just run a motor ! Why do you need a computer in there ?! Amazingly, the board works and was perplexingly the driest part in the whole machine, despite that box just having a POS metal lid with no gasket and no screws whatsoever that was all bent and not fitting properly, because the thing was kicked or knocked somewhere in a bottom corner and a lot of things no longer fit or close properly...*ARRRGHH !!
* Stuff like this just made it more and more annoying the more I dug into it and I would love to beat the crap out of that thing with a sledgehammer just because it's such a humongous piece of garbage stinking up my shop and soiling my hands and desk and wasting my time ! !
*RANT OVER*
When I turned it on, I could hear the rising frequency sweep vibrating the motor windings in the audible range, but it quickly shut back down and returned an error code (yeah, it's got a display at the top - did I mention "overkill" ?). I got the motor out and found THAT....game over, since there's no way you're restoring that, not with the rock bottom equipment we have here. Still, the motor's pretty interesting: it's got 8 wires going into it ! 3 fat ones and 5 thinner ones. In the picture of the control box, the first three are the black, white and red in the bottom-left corner and just above that terminal block there's the other 5...what is this motor ? Is it a three phase VFD-driven motor ? Why all the wires then ? There's a bridge rectifier, two large caps, 6 IRFP460 FETs and a handful of other small components, so it must be a VFD....STILL overkill IMO. Would it be possible to find a replacement for such a seemingly dedicated motor ? Swapping it would be a nightmare, since those wires pass through a moulded plug in the housing so I'd have to cut each one then individually solder them back onto the new motor, plus just the idea of working any further on this thing makes me sick...cheers guys
Getting past the ugly nature of the job, the actual problem came down to the motor itself which is far past f***ed (see the picture): moisture got sucked up through the bottom, into the whole machine, causing many of the metal parts to rust, including the impeller blades and part of the motor housing as you can see. The expansion of the rust actually caused the impeller to weld itself to the inside lip of the cover there ! I have no idea how it could've possibly ended up SO bad inside - you wouldn't think leftover water on hands can do this sort of damage, especially since it's (SHOULD BE !) designed to be immune to moisture...it's like they left it out in the rain on purpose just to screw with me...
It's also one of the most overkill and over engineered things I've ever seen...just look at that control board ! Was this really necessary ? It's a hand drier - you just run a motor ! Why do you need a computer in there ?! Amazingly, the board works and was perplexingly the driest part in the whole machine, despite that box just having a POS metal lid with no gasket and no screws whatsoever that was all bent and not fitting properly, because the thing was kicked or knocked somewhere in a bottom corner and a lot of things no longer fit or close properly...*ARRRGHH !!
* Stuff like this just made it more and more annoying the more I dug into it and I would love to beat the crap out of that thing with a sledgehammer just because it's such a humongous piece of garbage stinking up my shop and soiling my hands and desk and wasting my time ! !*RANT OVER*
When I turned it on, I could hear the rising frequency sweep vibrating the motor windings in the audible range, but it quickly shut back down and returned an error code (yeah, it's got a display at the top - did I mention "overkill" ?). I got the motor out and found THAT....game over, since there's no way you're restoring that, not with the rock bottom equipment we have here. Still, the motor's pretty interesting: it's got 8 wires going into it ! 3 fat ones and 5 thinner ones. In the picture of the control box, the first three are the black, white and red in the bottom-left corner and just above that terminal block there's the other 5...what is this motor ? Is it a three phase VFD-driven motor ? Why all the wires then ? There's a bridge rectifier, two large caps, 6 IRFP460 FETs and a handful of other small components, so it must be a VFD....STILL overkill IMO. Would it be possible to find a replacement for such a seemingly dedicated motor ? Swapping it would be a nightmare, since those wires pass through a moulded plug in the housing so I'd have to cut each one then individually solder them back onto the new motor, plus just the idea of working any further on this thing makes me sick...cheers guys
Attached Files
Comment