Electrical Motors.

[Brian]

I have a problem which someone out there who knows the ins and outs of electrical motors may be able to help.I have an evaporative air conditioner on the roof. Its a variable speed motor type and the motor sits in the base of the air con with the fan directly attached underneath it.Now, ever since I have had this air con, the motor stuffs up every 12 months, usually, sorry, nearly always on Saturday and after a special trip into town, 300 k's round trip and a new set of bearings, all is well again. Now, I'm aware that the motor can digest stuff that might happen to fall from the roof and also dust etc that could enter the air con over 12 months because the motor is open or has ventilated openings in its ends and sides. In Feb 04 I bought a brand new motor, made sure no water or spray was spilling on motor and set it going.As soon as the summer was over I cleaned the air conditioner and covered the electrical motor and also tied the fan up to stop it from windmilling which it used to do.In December I again cleaned out the air con cabinet, done the cleaning of pads etc. All was great. This afternoon, the motor stopped, on inspection I found the motor very very hot and the fan was very hard to rotate.It was 40 C in the shade and I wasnt cool[!] so I went for the can of CRC figuring I couldnt do any harm to anything so I squirted a lot of CRC into the motor, a lot of steam came out so I gave it more CRC till it stopped steaming I also moved the fan back and forth till it freeded up and then gave it a quick start up to see if it would run which it did. It was then turned off for 30 minutes or so till the CRC drained right out.The air con was then switched back on and it appears all is well for the time being.The question I have is WHY am I having all this trouble when particularly with this new motor, I have been at pains to make sure its looked after properly.I previously had a air can that went for 15 years without ever once stopping and had a very similiar looking motor except it wasnt a variable speed type.BrianYou never know how far you can go, till you get there !

[Mark Horan]

Are the new motors made in CHINA?. could be your ploblem --

[NiqueNaque]

Brian,I concur with Mark... the quality of alot of their stuff is poor at the moment, a bit like Japan in the early days.What make is it? Have you spoken to the manufacturer to see if there is a history of problems and a factory cure for the problem?Are the bearings sealed and are they installed with the shaft vertical or horizontal?If you've sprayed it with CRC and it now works that tells me that the unit is getting over hot and the lube is melting, getting so hot it is gassing and blowing itself out of the seals (if any), hence the eventual seizure. Try changing to an equivalent *sealed* higher quality bearing such as an SKF or Timken Bearing.Being an evaporative cooler means there will be a fair amount of moisture involved, it the motor separated from the moist airstream? Would the moisture condense on the bearings and get in to damage them? Could the moisture pool over the bearing?Have you pulled the bearing itself apart to see what they are like inside?Does the conditioner have a roof over the top of it and is the roof reflective, eg, zincalume finish? These factors will mean an additional heat load the unit has to cope with before it can even start to cool your house down, remove this load if you can by providing it with shade but do not crowd it and reduce its air flow.You probably already have insulation in the roof, but if not it helps immensely, as do roof ventilators.Hope this helps,Nick.

[Mark Horan]

Alternatively Brian,You could throw your can of CRC in the bin and get yourself a can of Lanolube!Finally, someone has found a use for sheep! (sorry to any Kiwi's out there) This stuff is fantastic, The lubricant in it is lanolin and unlike anything else Like WD or CRC, Anything you spray actually frees up and stays freed up.(It is even good for cleaning up your rotors, with the added advantage that cowsh!t doesnt seem to stick......as much)Mark.

[Brian]

Thank you very much for the replies and advice. I do apologize for posting this in the "Training area, my computer skills arent that good.The motor is Adelaide made and no, I havent spoken to the maufacturer[but I will]. The shaft is vertical and the motor is directly in the moist airstream and no, I havent pulled the bearings apart but I will get the bearings changed to the better quality. I used CRC because I'm right out of Lanotec.WOW, even use it on cleaning the rotors, sounds great, probably even cheaper than Mr Sheen !!Nick, I think you have it pretty right ie, the motor getting too hot and the lube melting and the bearing then seizing. Its pretty well impossible to cover the motor as this would then stop air from circulating through the motor.I'm a sheep breeder too Mark ......there are some that I would like to render down to Lanolube too, unfortunately they are too valuable at the moment.You never know how far you can go, till you get there !

[NiqueNaque]

Ever tried to clean bird shiit off your rotors... it is a ******* to remove, sometimes nothing short of a chisel will get it off.I found this great new stuff for doing it... s p i t .. dissolves it in a flash.Cheers,Nick.

[asra]

Nick, "spit" that is called "Gob oil"!!!!!!!!!!!!Aussie Paul.[]www.firebirdgyros.com

[Brian]

Autosol is the stuff to get every stain off and make those alloys flash in the sun!!Trouble is, you have to shine both rotors.You never know how far you can go, till you get there !

[Brian]

It is a fan type Ozy, but from memory, the fan is fixed pitch but when the motor gets back, I will have another look. The motor is nearly always run on the lowest speed setting.You never know how far you can go, till you get there !

[Brian]

What details would tell you how the motor is configured?Thats interesting that the motor might have the largest current draw at low speed !Will take your advice and turn up the speed.....when the motor makes it back ! Will be talking to the repairers tomorrow to find out more info. Would be interesting to have a remote temp sender on the motor to see what variations of temp actually are.You never know how far you can go, till you get there !

[Brian]

Okay, its now friday, picked the motor up yesterday, just new bearings were needed. Was told the bearings replaced were stuffed and was assured that the new bearings are the very best sealed bearings. No water had entered the motor. Tried to take some pitch of the fan but the screws were rusty and were too tight so I left it be.The fellow who fixed it wasnt there so wasnt able to find out if the bearings were dry etc.Anyway, its going just fine now and the work was done under warranty, so now have another 12 months warranty on the bearings which doesnt impress as its taken nearly a week to get the air con back working and it was a bit over 40 here yesterday.You never know how far you can go, till you get there !

[asra]

Brian sound like your unit is quite old or cheap. The reason I say that is because most evaporative coolers these days have what is called Tropical sealed motor,(using windings to tropic proof standards)and IP23 ratings, which means they are fully sealed from there enviroment. Also most of these motors have lots of cooling fins to dissepate the generated heat. They also run a small shaft driven fan to help with cooling. During operation these motors when run at very slow speeds build up heat due to a lack of cooling effect from its shaft driven fan, so usually incorporate an over temperature cut out.Bonaire garantees their Super Sensor V motors for 3 years.I have had mine, which I installed, for 6 years,& still going strong!!Regards Sam.

[Brian]

Thanks Sam.Thinking about other electric motors around the farm, are all sealed units just as you described Sam, sealed and have fins with a fan on the top providing cooling air.I'm getting ripped off and wasnt wise enough to see it !!Its amazing to have the obvious pointed out to you !!Thanks Sam !!You never know how far you can go, till you get there !