Repairing an electric motor flooded by detergent! HELP!

[edy]

A colleague of mine has a Hydrim L110w instrument washer from SciCan:

https://www.scican.com/products/instrument-washers/hydrim-l110-and-m2

Of a number of stupid design decisions, they decided to place an exposed "detergent dosing" motor right under the liquid detergent chamber. The Hydrim "HIP solution" is a bag of liquid detergent in a cardboard box which you connect to the machine by screwing on tubing. Have a look at this video below...

Time stamp 4:24 - 4:34: See dosing pump motor lower right corner under detergent box holder
Time stamp 5:26 - 6:00: Location of detergent box and screwed-on tubing



Somebody didn't screw the detergent box on properly to the tube and it leaked (detergent placed upside-down like an "IV bag"). That area isn't water tight so the entire box of soap leaked down and flooded the dosing pump motor. I've attached some photos.

My question is, looks like only the coil was damaged mostly. Probably shorted and burned some wires when still soaked. Can the remaining motor components (is it a simple AC induction motor?) be disassembled and cleaned? How is the coil wound around the plates, is it removable? The motor operates a peristaltic pump at around 49 RPM (see sticker on coil). I assume 30 seconds on, 5 minutes off to cool? A replacement is costing upwards of $500-600 which if an alternative repair or motor is available would sure be desirable. Needless to say with equipment like this, every part feels like highway robbery or maybe that's just what they cost to make?

[Gyro]

Looks like soapy fun.

As it's a bog standard shaded poll induction motor, there isn't anything to electrically damage other than the coil. Also, as it's an AC motor, there's little chance of electrolytic corrosion of the wire.

If the motor hasn't already dried out (and maybe if it has) I would be tempted to give it a good soak, motor downwards, gearbox up out of the water to flush out as much detergent as possible from the coil and bearings. Maybe do a few refills.

As it's a peristaltic pump, it should be easy to take apart and clean. You probably want to check that no detergent has got into the gearbox. If so, you'll need to get it out and re-grease.

I doubt that the motor winding has actually been damaged (unless the detergent is capable of dissolving magnet wire insulation). I would first try flushing the detergent out (as above) and then give it a good dry, first with a hair dryer to get the surface water off/out, and then a prolonged dry in a warm place.

The detergent may have washed the oil out of the motor bearings, so a little sewing machine oil wouldn't go amiss.

[Runco990]

That's a $10 motor to begin with... so highway robbery IS the correct term.

If you have access to an ultrasonic cleaner, take the motor apart and wash it in distilled water for a while, then soak in 99% alcohol to drive out any moisture.  Let dry in warm place, oil and re-assemble.

I doubt any harm was done.  These simple motors are almost un-killable.  Had may aquarium pumps with those... they would start to rattle as the bearings just plain wore out, but they never died, water and all.

I wash electronics and motors and such regularly like this.  No problems whatsoever.  You really just want to get rid of the detergent.

[ace1903]

Stator core is welded on this motor. Nearly impossible to rewind. Also think that there are no bearings only bronze bushings.
Check for thermal fuse under plastic foil on the winding. My experience is that water while working nearly sure destroys the winding.
I had 100s  induction motors that were flooded with muddy water (in flooding similar to that that happened in Germany week ago)
and all of them after cleaning and baking several hours at 100C  and bearings replacement work several years.
But couple motors that were powered while showered with drinking water developed short in the winding or large leakage towards earth.
This motor is standard and widely used in fans in HVAC and some search could result in 10$  replacement.

[coppercone2]

you can rewind it, but only in India. I have seen them do it.

[najrao]

Rewinding the coil is quite simple. The two parts of the core attach at the 'dovetails', and can be separated in a vise. The part with the coil on the former/bobbin can be chucked in a drill or similar. Rip off the damaged winding, counting the turns well as possible; helps to measure resistance and estimate turns if counting proves awkward. Use new wire of the same gauge, naturally. A few % error in the turns count won't matter. Reattach the core parts by pressing together.

[Rasz]

A replacement is costing upwards of $500-600

thats the price of full Bafang 1KW conversion kit for a bike .... Dont look at the dealer price, get  a model number and look for the oem one, unless its a  custom one of a kind thing.
Edit: looked at the pictures, yep this looks like a run of the mill $10 shaded pole induction motor I got in my bathroom powering the fan.

[Gregg]

I may be missing something, but this motor doesn’t seem to be bog stock as it has 3 leads for the coil.  That may limit finding another motor with the same coil, lamination stack and rotor diameter to make an easy swap.  However the third wire may go to a thermal switch or other overload device that may be replaceable by a clever person.
Try taking off the tape over the coil and looking at the damage.

[Gyro]

I may be missing something, but this motor doesn’t seem to be bog stock as it has 3 leads for the coil.  That may limit finding another motor with the same coil, lamination stack and rotor diameter to make an easy swap.  However the third wire may go to a thermal switch or other overload device that may be replaceable by a clever person.
Try taking off the tape over the coil and looking at the damage.

Ah, you're right. Looking closely at the images, one lead is labelled COM (common) and the other two '50Hz terminal' and '60Hz terminal'. The  label says that the motor is 240V 60/50Hz rather than 240V 50Hz / 120V 60Hz. Also the FLA (full load amps) is 0.75A / 0.6A.

I can only assume that the coil has a slight overwind on the winding to cause additional rotor slip, when running on 60Hz, to drop the speed when under load. [Edit: or to provide a bit more torque at 50Hz] That sounds like a bit of a bodge way of doing things, but there again, a shaded pole motor that can only sustain 30s on / 5min off is a bit of a bodge anyway!

[Gregg]

Gyro, your eyesight is better than mine.
If the motor is only going to be used in Canada with 60Hz there is no need for fancy windings and I'm sure the RPM isn't too critical for a soap pump.  The pump pulses may have different timing settings for different frequencies on such a fancy washing machine.  The duty cycle ratings printed on the motor may be factory de-ratings for compliance requirements of some end users and to scare off self service of their equipment.  If the pump timing is really critical, I would think they would have used a stepper motor.
I personally would take the motor to a Johnstone Supply and try to get a sympathetic person at the counter to find a universal replacement motor with the same lamination stack and just swap that part of the motor.  The rotating armature of the existing motor probably wasn't hurt from soap, but the bearing toward the gearbox may need attention.
There are a number of companies on line that list shaded pole motors by size

[Gyro]

Not bad for my eyesight - although I totally failed to notice the 3 wires. 

I agree, a single winding could be bodged for Canada, the thing that worries me a bit is that those full load currents are huge for a little shaded pole motor like that - they must be pushing it really hard. There are too many air gaps for it to actually saturate but everything must be heating up very rapidly. This potentially poses a problem with finding a replacement (unless you maybe overload a 120V one). Most little shaded pole motors like that are in the 15-25W range, this one's pulling 0.75A at 240V!

I guess it depends what is on the end of the motor shaft in the gearbox too - hopefully the gear is easily removable and reusable and it's possible to match the shaft diameter. The ideal solution would be to find a new stator that would take the existing rotor and bottom bearing mounts, but life is rarely that simple!


Edit: I'm beginning to think that a rewind (if actually necessary) is the easiest option. I suspect it might just be a case of re-terminating the ends of the winding, those would have been the only exposed copper when it got soaked - I doubt the detergent has an appetite for Polyurethane.  Re-insulating wouldn't be a problem.

[andy3055]

najrao is correct. The motor coil and that section of the core can be taken out. Carefully take out the outer insulation and inspect the damage. May be the soldered top end has sparked and melted. If so, you can clean, re-solder and put it back together. Wash the thing including the coil with gasoline and dry in the hot sun. Make sure there is no short from the coil to the metal core. Re-assemble and test.

If the coil is bad and you cannot get a replacement motor, rewind the coil with the same gauge wire. Sometimes only the few top layers get damaged and you can do a splice and "fill back" with enough wire. These coils do not need to be very accurate.

Make sure you lubricate the bearings well.

[ijchan223]

i have never seen a shaded pole motor that run at such a low rpm 49/41? there has to be a gear reduction built in. 

[andy3055]

3rd photo shows the gear box.