Replacing a capacitor
Discussion
I have an outdoor water pump that has been a bit temperamental lately. Its activated by an electronic timer and recently it has either not come on at all, or started and then quit at some point during the day. I've been able to get it going by gently tapping the motor case with a rubber mallet, which suggests to me that the motor itself is shagged-out. However, it was suggested to me that the capacitor on the motor often causes these problems and I should try replacing that first ($30, vs $300 for a new motor). Now I read somewher that you have to be a bit careful with capacitors, because it is possible to get a fair old belt off one, even when the supply circuit is disconnected.
Before I go poking around and do myself a mischief, is there a method of discharging the capacitor, prior to removing it from its housing?
Before I go poking around and do myself a mischief, is there a method of discharging the capacitor, prior to removing it from its housing?
Matt Harper said:
No clue, I'm afraid chaps. It's attached to a 1.5hp 230vac pool pump and is about the size of a flashlight battery.
Actually that sounds quite meaty. I can't do the 'microfarad' symbol (mju F) on this keyboard but does it have any writing on it?Oh sod it, just short the f
ker out with a screwdriver 
Simpo Two said:
I think the capacitor in this instance is just a smoothing one, and not the kind designed to fire studio flashes. What is its physical size and what capcity in microfarads?
This sounds like a single phase induction motor. A capacitor will throw the current out of phase and powers a second set of windings to get two phases from a single phase supply. Info here.
OP - Can you post a photo of the motor and data plate?
Ganglandboss said:
This sounds like a single phase induction motor. A capacitor will throw the current out of phase and powers a second set of windings to get two phases from a single phase supply.
Info here.
Two phase electricty! Well you learn something new every day.Info here.
Now the part of me that's Thomas Edison is wondering if you can make three-phase using two capacitors
Ganglandboss said:
OP - Can you post a photo of the motor and data plate?
Ignore the green ground wires - I disconnected them from a defunct electric pool heater that is next to this. I think the pump/motor has been sitting out in the heat/rain/hurricanes for around 15 years. The data plate was a sticky label affair that peeled off eons ago.
The capacitor is under the casing on top of the motor body. I'm pretty resigned to replacing the entire motor - but if I can get another 6 months out of it for the price of a capacitor - then what the hell. What I don't want to do, is shock myself removing/replacing the component - hence the initial question.
Thanks for the replies.
Just as an aside, what usually causes the motor to fail is a breakdown of the gasket between the pump and the motor shaft, which allows water from the pump to contaminate the motor spindle bearings. There isn't any evidence (that I can see) of water ingress into the motor from the pump - and when it was running, it was not squeaky/noisey.
The motor does look about due for replacement. It has had to work hard (22,000gal pool with sweep and solar heater on my roof) - but a few folk have said - "Nah, just change the capacitor and you'll be golden".
The motor does look about due for replacement. It has had to work hard (22,000gal pool with sweep and solar heater on my roof) - but a few folk have said - "Nah, just change the capacitor and you'll be golden".
How big is the pool, What HP motor is it - From when I worked out there you could get 1.5hp pumps for about $150.00 from your local Pinch you pennys store or even better try an independant store...It's 22k gallons and the pump motor is 1.5hp. Pinch-A-Penny want just over $300 for a Pent-Air or Hayward replacement motor - and suggest I would be far better off replacing the whole unit (i.e. the pump aswell). There is absolutely nothing wrong with the pump - and I'd have to do a lot of re-piping to boot. I buy my chems from them - but they take the piss price-wise for hardware.
I'm pretty confident about everything - other than the capacitor. My understanding is that they can hold a potential charge for some time - so I was hoping that someone in the know could advise me on how to handle it without giving myself a hefty shock, or burning my house down....
I'm pretty confident about everything - other than the capacitor. My understanding is that they can hold a potential charge for some time - so I was hoping that someone in the know could advise me on how to handle it without giving myself a hefty shock, or burning my house down....
Just short the two terminals together with a piece of insulated wire or a pair of insulated pliers,you may see a little flash if it's still charged.
If the case is still readable there will be microfarad( uF )amount printed on it.
In this case it's 10 uF.
Problem with the older ones were in a metal case which rusts and then you can't read them.
If the case is still readable there will be microfarad( uF )amount printed on it.
In this case it's 10 uF.
Problem with the older ones were in a metal case which rusts and then you can't read them.
Edited by netherfield on Tuesday 25th August 18:30
Matt Harper said:
It's 22k gallons and the pump motor is 1.5hp. Pinch-A-Penny want just over $300 for a Pent-Air or Hayward replacement motor - and suggest I would be far better off replacing the whole unit (i.e. the pump aswell). There is absolutely nothing wrong with the pump - and I'd have to do a lot of re-piping to boot. I buy my chems from them - but they take the piss price-wise for hardware.
I'm pretty confident about everything - other than the capacitor. My understanding is that they can hold a potential charge for some time - so I was hoping that someone in the know could advise me on how to handle it without giving myself a hefty shock, or burning my house down....
If the capacitor is goosed it won't be holding any charge so no need to worry about handling issues. I'm pretty confident about everything - other than the capacitor. My understanding is that they can hold a potential charge for some time - so I was hoping that someone in the know could advise me on how to handle it without giving myself a hefty shock, or burning my house down....
If it is holding it's charge place a resistor across the 2 contats to avoid the sparking discharge.
If the capacitor is across the motor winding like it sould be then it wont hold any voltage at all as the resistance of the motor windings will discharge it. They are usually a very small value as there use is mainly for inteference supression. Whacking the motor and making it works is proberbly more of a bad connection than anyhthing else.
Edited by headcase on Wednesday 26th August 20:04
Gassing Station | Homes, Gardens and DIY | Top of Page | What's New | My Stuff