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Old 03-17-2009, 03:48 PM   #1
Fireball
 
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Thumbs up Centrifugal switch problem, or is it?

I'm back again with another motor problem with a greenhouse fan.

I have a 1hp 1ph 230v motor that will barely turn and gives a nice loud hum. Once I (carefully) grab the fan blade and give it a whirl the motor slowly gets to full speed. To me this sounds like the centrifugal switch or a problem with the start winding. This fan is directly installed onto the shaft of the motor and seems like a pain to remove and take it to the local motor shop. I can easily access the back to work on. I haven't taken apart a single phase motor since trade school so any help would be appreciated. Oh ya, I did check the line voltage and it is good.

Any ideas? Thanks

jeff

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Old 03-17-2009, 04:33 PM   #2
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Sounds like a capacitor.

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Old 03-17-2009, 08:34 PM   #3
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Quote:
Originally Posted by AussieApprentice View Post
Sounds like a capacitor.
I 2nd that. If there is one.
Another trick I have used,With power off.

Contact cleaner. spray and spin (by hand) That has worked wonders for me in the past.
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Old 03-18-2009, 09:31 AM   #4
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Funny you mention that but there is a capacitor. So if it was the centrifugal switch then it wouldn't start at all, or just run slow.

jeff
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Old 03-18-2009, 06:59 PM   #5
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Originally Posted by tburg jeff View Post
Funny you mention that but there is a capacitor. So if it was the centrifugal switch then it wouldn't start at all, or just run slow.

jeff
If you have a Capacitor-start induction run motor the capacitor and the centrifugal switch are connected in series with the start winding. If the cap is OK then you probably had the centrifugal switch get stuck in the closed position and it fried your start winding. Also starting and stopping this motor frequently can damage the cap because of over heating. If the centrifugal switch was bad assuming stuck in the open position the motor would never have the starting torque to start and it would not have a rotating magnetic field to start . However if you turn the motor by hand you create a rotating magnetic field the motor will take off and run through the run winding.

Last edited by 5volts; 03-18-2009 at 10:03 PM.
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Old 03-19-2009, 09:53 AM   #6
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well thanks for the re-education. The motor would spin slowly once powered. To paraphrase- if the switch was stuck or the start winding fried it wouldn't turn at alll for start up so that leaves the capacitor.

I took the motor down and brought it to the local motor shop. I will post the results.

thanks again for your help

jeff
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Old 03-21-2009, 12:23 PM   #7
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A new one will cost less than a motor shop, even if the motor is good. Labor and bearings will be the least they will do.
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Old 03-30-2009, 04:32 PM   #8
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Ya it turns out it was the capacitor. $145.00 Canadian to replace it and the bearings.

thanks again for your help

jeff
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Old 04-03-2009, 02:30 PM   #9
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Originally Posted by tburg jeff View Post
Ya it turns out it was the capacitor. $145.00 Canadian to replace it and the bearings.

thanks again for your help

jeff
Found several brand new motors with warranty for $130 - $160 US dollars. Depending on frame and type.
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Old 04-06-2009, 08:38 PM   #10
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greenhouse ,make sure its a TEAO motor
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Old 04-10-2009, 08:30 PM   #11
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Up here in Canada our dollar is only worth 80% of the american dollar, in addition we have an 7% tax on everything but food. Plus because it is Canada everything is marked up compared to the states. So the same motor will cost us at least 250.00. I won't even get into the difference we pay for cars and books etc..........

Since my last writing I sent three more motors into the shop to get the capacitor fixed. Apparently with this brand (made in the usa) the capacitors aren't very good and only last a few years.

I am not sure what a TEAO motor is but thes motors are specific for use for a four by four fan. The real pain of this style is that the fan blade is directly bolted onto the motor shaft. The motor is bolted onto six two foot metal strips of flatstock in a star formation. A complete pain to take on and off........which lead me to ask the original question wether I could fix them while they were still affixed to the fan assembly.

Most of the other motors are belt driven but I am not sure what this TEAO means?


thanks

jeff
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Old 04-11-2009, 01:33 AM   #12
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TEAO = Totally Enclosed Air-Over. This motor is completely enclosed, but needs to be in the airstream for cooling.

TEFC = Totally Enclosed Fan Cooled. This motor is also completely enclosed, but has a built-in fan to cool it.

TENV = This motor is also completely enclosed, and doesn't need forced air to be cooled. It depends on convection air for cooling.

OPAO = Open Air-Over. This motor is not enclosed, but needs to be in the airstream for cooling.

ODP = Open Drip-Proof. This motor is not enclosed, and a cooling fan built into it. It can be exposed to falling rain, provided the angle of the raindrops doesn't exceed 15 degrees.

Capacitors are easy to test, and easy to replace. They cost about $10-20. The MFD rating needs to be pretty close, the voltage rating of the replacement can be higher, but not lower. If it's only two terminals, polarity doesn't matter.

Rob
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Old 04-11-2009, 10:05 AM   #13
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okay thanks for the info. I don't recall a fan on any but I am going to definately take a look.

It does seem easy to access the capacitor. The guy at the motor shop also replaced two bearing balls. The labour was 103.50 plus taxes. I am not sure what the bearing balls have to do with the capacitor? Am I getting stiffed????

thanks guys

jeff
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Old 04-11-2009, 10:07 AM   #14
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the motor is a leeson catalog#M009648
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Old 04-11-2009, 11:42 AM   #15
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Generally speaking, any time a motor is brought into a shop, they'll replace the bearings. Small bearings like this are not very expensive, less than $10 each. It takes about 15 minutes on a little motor like this.

Motors with shaft-mounted fans are notoriously hard on bearings, and this could easily be the problem. If a bearing is bad, and there's any slop to it, the rotor will not be exactly centered in the stator. (The rotor is the part that turns, the stator is the outer part that has the windings in it.) This will give about the same symptoms as a bad capacitor, or a bad start switch.

It'll try to start, but just can't quite come up to speed. If it does come up to speed, it'll run, but not have as much power as normal, and be noisier.

If I had a motor that was disconnected from the driven apparatus, I'd replace the bearings as well as anything else that could cause problems later on.

Given the part number, there's a possibility that this motor doesn't have a start switch at all. A lot of Leesons motors with a part number that starts with 'M' are PSC type. (Permanent Split Capacitor.) The capacitor is always in the circuit, whereas a capacitor start motor uses its capacitor only during starting.

You can tell which motor you have by looking at the capacitor. If the MFD rating is under 80, it's almost certainly a PSC. If it's above 100, it's likely a capacitor start.

Rob

Last edited by micromind; 04-11-2009 at 11:44 AM.
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Old 04-12-2009, 09:04 AM   #16
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Okay thanks, I will check the rating and hopefully just change the capacitor.

jeff

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