Replies

1. 
   Scott | Jul 02, 2012 04:15pm | #1

   My understanding is that they don't last forever, so it may be a simple case of old age. This is one reason why they make two-wire and three-wire pumps. Mine is a three-wire version, so the capacitor is up top and can easily be replaced.

   I dread the day I have to hoist my pump up, so I gladly forked out a bit more money for the three wire design.

2. 
   DanH | Jul 02, 2012 08:58pm | #2

   The most common cause of run capacator failure is run capacator failure.  A microscopic short develops and "grows" until it overheats the unit and "Poof!"  Sith happens.

3. 
   DanH | Jul 02, 2012 09:49pm | #3

   Understand how an electrolytic capacitor is made.  Basically, two strips of aluminum foil are separated by a piece of porous paper and rolled up.  Then the paper is saturated with the "electrolyte" that is a hair like battery acid.  Finally, a current is run between the two foil strips (through the electrolyte).  This causes a thin layer of oxide to build up on the foil, and it's the oxide that is the insulator in the capacitor.  (This isn't much different from the way that a lead-acid battery works, only with the battery a chemical change occurs as the battery charges.  No chemical changes occur in the cap's oxide layer once "formed", however -- just electrons get displaced in the voltage field.)

   It doesn't take much -- a minor impurity -- for the oxide layer to be "poisoned" and develop a "hole".  Over time the hole will grow, current will increase, and eventually the cap will fail.  (Or vibration can cause a short mechanically.)

1. 
   Scott | Jul 03, 2012 01:10am | #4

   >>>Understand how an

   >>>Understand how an electrolytic capacitor is made.

   Thanks for that explanation. It reinforces the fact that eventually a cap will fail. Sorta like an internal combustion engine.

   I've yet to replace the control box for my well pump. I'm hoping this means it's got some lifetime ahead.

1. 
   DanH | Jul 03, 2012 06:53am | #5

   Yeah, failed electrolytic capacitors are the #1 cause of electronics failures.

1. 
   davidmeiland | Jul 03, 2012 02:50pm | #6

   Nice

   explanation, thanks

2. 
   Tim | Jul 10, 2012 12:53pm | #13

   Thanks

   Dan. Great explanation.

4. 
   Scott | Jul 06, 2012 01:36am | #7

   Haa!!!

   The compressor motor in my heat pump went Hummmmmm..... today on it's first taste of A/C this year.

   Sure enough, I found a bubbled cap in the control box.

   This has been a timely thread for me.

   Thanks all.

1. 
   DanH | Jul 06, 2012 07:02am | #8

   Actuallly, capacitors are filled with words.  Motors get their words from the capacitors.  When the words run out the cap bubbles up and the motors hum, because they don't know the words.

1. 
   Hokuto | Jul 06, 2012 08:54am | #9

   ?????

   Back about a century ago--actually, the very same period in which Nikola Tesla was active--some very inventive people were experimenting with capacitors composed, by design, with hums instead of words. Unfortunately, the only one that left a mark was a guy named Puccini, who composed a butterfly capacitor entirely of hums.

1. 
   Scott | Jul 06, 2012 11:28am | #10

   Har har har.... could you guys please pass the corn....

5. 
   [email protected] | Jul 06, 2012 11:49am | #11

   NO, it's smoke

   All electronic and electrical devices run on smoke. 

   As proof I submit:  That when some or all the smoke escapes, the device will not run correctly, if it runs at all. 

   The picture of the capacitor, the original poster submitted, clearly shows that the smoke left the device.  It no longer works. 

1. 
   Tim | Jul 10, 2012 12:57pm | #15

   That

   was my first guess. I let the smoke out. And some waxy goo, too. Don't know if that stuff is important ans the smoke, though...

6. 
   kevinbrown966 | Jul 09, 2012 02:42pm | #12

   hey, you are welcome. glad that you appreciated my explanation. i'll keep posting!!

7. 
   Tim | Jul 10, 2012 12:54pm | #14

   Thanks

   for the input, Kevin. I was away for a while, sorry for the delay in response.

8. 
   Tim | Jul 10, 2012 01:04pm | #16

   Some further investigation

   revealed a slight undervoltage situation. Was running at about 200V instead of 240V. That problem has been solved. Don't know if it contributed to the failure or not. New capacitor installed, motor works great! Thanks for everyones input and info. I wanted to be sure that a fault in the motor wouldn't cause the capacitor to fail. $10 capacitor takes out a $1200 pump. Gotta love it.

   So......anyone want to buy a 2 hp, 12,500 gph waterfall/pond pump? New capacitor (full of smoke) included!

1. 
   DanH | Jul 10, 2012 09:04pm | #17

   Undervoltage could slightly increase the load on the cap, causing it to get warmer and fail a little sooner.  Would be unlikely to be the root cause of failure, though.