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Electric Motors/Doerr Emerson LR22132 Capacitors

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Question
This motor has a 56 frame. The model is: T63BXBNC 1010. It runs on 117vac. With no load it seems to run fine. Under light load is slows to a stop rapidly. I am wondering if the capacitor(s) are bad. There are two mounted on top of the motor. They dont seem to be matched. One has a two wire connection and is a 324-389 MFD 165vac rating (Phillips)Is this the start capacitor? The other has three wires connected (run capacitor?) and is rated as 20 MF 370vac (Aeromet II). My question is what are the correct ratings for both of the capacitors on this motor? One has two wires the other three wires. I want to replace the caps with the right ones. Thank You for any information on this!

Answer
Troy,  the values can be all over the board,  there is no linear relationship from hp or voltage or anything to the cap values,    and trying to get specific old Doerr data is near impossible, but there is a typical range of values and both of yours are right in the middle of the typical tolerances.  

In the wide range of capacitors,  both sound about right,  the run would be the small mfd rating,  probably in a metal can,  the start would be higher mfd, it would be in a plastic like black colored can.  The run might be round, most are oval,  and the start should be round,   but it is the values that count,        

This would give you a cap start cap run motor,    someway internally the three leads probably tie the caps together,     but not a problem,     just make sure the three wire is not a dual rated cap,   but I doubt it,    mark the WIRES TO THE TERMINALS AND TAKE A PHOTO !

The two on the start make no difference, the three on the start will,     there are no polarity concerns on the start,     and just a jumper on the run, so we need it back on the right terminals  it has three wires,  but probably has four spade terminals one unused,    

Yes an open cap would cause some weakness in the motor,   and if one is bad the other is old enough to be replaced also,    and use the same capacitance as you see,  the voltage ratings need to be what they are or higher,   in other words, if you cannot find a 165 volt cap,  a 370 volt or 220 volt will work fine   it is a max rating and not an operational value.

It is a little odd to see a start cap at 165 volts, but the motor is probably rated 115/230 or 115 or 110/220. The start winding if dual voltage is still on the lower value regardless of the motor connected value,   they take the start winding and on high voltage of dual rated motor,  use a center tap in the external connection so the start winding is always on the low value, that way a 165 volt RATING is fine,     again it is max voltage rating  so it can be higher but not lower,     although an mfd of this much is going to be hard to find in a lower voltage rating,    

Don't be concerned with the differences in values of the caps,   that is normal.

This is the least expensive test you can do,  replace BOTH CAPS    [if you want start with the RUN   the three leaded cap ,   see if that resolves the problem,   but if it does,  it is fixed however the start cap is probably ready to go,  for sure it is not as strong as a new one, and should only be maybe 30 bucks for the pair, tops,    if you shop around  you should find the two for even less than that.

If the caps do not fix the problem  look to the starting switch  [both the stationary and the centrifugal parts]  check the contacts, check the centrifugal for weak or broken springs, worn bore where the sleeve has lots of slop from the wear, they can cock and hang up,   causing the motor to be running on the start winding only          

Until you are back to running correctly    try and keep the power off,  running on the start winding is often not discovered and you do not want to burn the start winding out    

But it does sound like a bad,  weak,  or open cap,   the values not a problem.

A typical start cap is right around that value  and a typical run is often around 20 or so mfd,  so no matching is needed, two completely different purposes,

If you want to write back at my shop it is MEAR Services in Kansas City,   repair@mearservice.com  or phone is 816-650-4030  or my personal email  wbwill@sbcglobal.net

or you can reply through allexperts if the replaced caps are not a solution, I can go deeper into the evaluation of the switch,  then windings,  so on,     

Will Babbitt  

Electric Motors

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Three phase/ AC DC single phase motors, controls, any problems or failures, motor installation, performance issues, connections. All other electric motors/gearboxes/apparatus. Specialty repair concerns, obsolete motors and solutions. Other mechanical or specialty equipment. See my profile under Home/electrical at this site

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30 plus years in the electrical motor and apparatus repair industry. VP level management of repair facilities, current owner of my own specialty repair and consulting firm.

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4 year technical, College level specific courses, EASA repair courses, vibration analysis electronic and electrical trade school.

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