MadModder
The Shop => Electronics & IC Programing => Topic started by: ieezitin on December 28, 2009, 07:18:07 PM
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Gentlemen.
My knowledge of electronics is very limited and I would like some advice on what is wrong with my pump. This is an industrial submersible pump and today I needed to pump out a field on my farm as we have had so much water I need to get rid of it or it will spoil my pasture.
The symptoms are this. Pump hums when power is applied and seems to be drawing so much power, the spindle starts then locks but if hit with a screwdriver the shaft takes off at full speed then rotates at full speed but the housing gets very hot then overloads the fuse which in turn shuts down. This is an oil enclosed pump and by the time the fuse goes the unit is too hot to touch.
The specs are this 3/4 hp, FLA 10.5, RPM3450, 60HTZ, 1 PH
All ideas are welcome. I thank you in advance. Anthony.
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2412.jpg)
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2413.jpg)
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2414.jpg)
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2416.jpg)
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2417.jpg)
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2418.jpg)
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This sounds like a tight or seizing bearing. If you spin the rotor by hand with the power off does it feel rough or sound noisy? If so then there are two options.
If it is an expensive pump, it may be worth finding out how feasible it is to change the bearings. However, it's sometimes a horribly fiddly job on small rotors like that so if it is a cheap pump it may be better to simply replace the pump.
The only other possibility is a fault on the start capacitor or start winding on the stator.
Check the bearings first, if it's not them I will run you through the method for testing the electrics.
Best of luck.
one_rod.
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One rod.
Well. When the power is off I rotate the spindle and it feels slightly lumpy but smooth if that makes sense .Bearings seem ok at least the top set but not have dug in the bottom of the casting This unit has not been ran for over a year that maybe of some interest.
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In the picture of the capacitor the end appears to be slightly convex. This may just be the camera angle but if it is convex that is a pretty good indication of a bad capacitor. The end cap on new caps are perfectly flat.
Joe
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My guess would be the starting capacitor as well. It's a cheap part so worth changing to see :thumbup:
Have a look to see if the old one has any numbers on it. The voltage rating is important, you can replace with a higher voltage rating but not lower. The uf rating is not so critical, something close should do.
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When you spun it, was it in the same position it would be when pumping? My vote would be one of the bearings. If that is a run capacitor, the start winding could be staying engaged. If it is start capacitor, may not be strong enough to overcome binding bearings until banged around. Stand it on end and spin the rotor and see if it is not grinding.
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75 plus
Here is a better picture of the capacitor in a close up and it is rounded.
Tinkerer,
I had it standing in the same position as it was to be worked. It turned on hummed a while then with me hitting the impeller it raced off but like I said lord did it get hot after a while, also my florescent lights went Bananas.
Darren
Got hold of the company for a price of a new capacitor today.
Now. I have a multy meter any ideas to check if it is the capacitor or windings?
One more question!.. It seems to me that the stator and rotor are immersed in a thin oil maybe about 1 pint of oil why does it not short out? Many thanks for all your help here... Anthony
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2419.jpg)
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2421.jpg)
(http://i721.photobucket.com/albums/ww212/ieezitin/Machine%20shop/pump/IMG_2423.jpg)
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The capacitor is definitely BAD. From the value it appears to be a run capacitor but it may be the reason the pump does not start properly. Replacing the capacitor should cure the heating problem. If there is a W.W. Grainger store anywhere near you they should have a replacement at a much better price than the pump maker.
As for the oil, these pumps run submerged in oil to preclude water from entering the housing. It is known as transformer oil and is dielectric (non conductive). A readily available substitute is common mineral oil sold as a laxative at most, if not all, drug stores. You will need to fill it to capacity and seal it well.
Let us know how you get on with it.
Joe
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75 plus
I thank you for your advice and knowledge, it was Granger I phoned today for a replacement capacitor just waiting now for a price and delivery.
You have all helped a lot in my problem many thanks. I will be posting the result of the new capacitor installation and to see if it works.
I am going to post a thread on How Toos on electrical problems as I think there is a lot of mechanical guys like me out there who are not versed in simple electrical work and know how.
Many thanks Anthony.
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Hi Anthony,
I'd also say deff the cap, it's only a baby one and should not cost more that a few dollars.
The oil is an insulator, as previously stated it makes a good coolant in many electronic devices.
You are not realistically going to be able to test the cap at home without the correct equipment, it's a relativity complicated process.
Caps are so cheap even the electronics guys just swap suspected caps rather than test them.
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Been using this capacitor tester for over 20 years. Have yet to find a swollen capacitor that checked good.
Joe
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Yes they used to be very expensive but I gather cap testers have come down a bit now?
How large a cap can it test up to, voltage and uf wise ?
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How large a cap can it test up to, voltage and uf wise ?
It will test from one pico farad (micro micro) to 20 milli farad (20 thousandth of a farad). It does not test for insulation breakdown as it only uses a 9 volt battery.
I bought it in the late 80's or early 90's. Think I paid about $40 US for it.
Joe
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Darren
I use one of these wotsits, not a 'stress tester' for caps but very accurate. Handy little tool to have. Chuffed with it... I have/had some 10k .01% resistors from an old analogue computer, they all read OK, so I surmise the thing is about spot on. (That's right 0.01% 1:10,000 :) )
http://www.test-meter.co.uk/products/lcr-meters/peak-atlas-lcr-meter-lcr40/
Got it some 3/4 yrs ago when Maplin mometarily lost a grip of their lifetime philosophy and sold 'em for less than Rapid/Farnell/CPC.
T'was £55 IIRC
Dave BC
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I don't think there is anything wrong with the cap apperence wise. It looks like it was manufactured like that. The insulation may have broken down inside.
Bascially this breaks down to 2 possible problems electrical or mechanical. Since it's easier to replace the cap that would be first on my list. If that doesn't cure it, then I would think there is a binding in the bearings somewere when it gets warmed up.
Bernd
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Thinking some more, if that is a run capacitor, then there must be a start winding that should kick out when up to speed. If it isn't kicking out :zap:
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i cant answer that one .... but ya its broken :D i was bored sorry :) :headbang: :beer: :mmr:
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Hey Anthony,
Whats the status of your pump? :scratch: :scratch:
Joe
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Joe.
Funny you should mention this. I got in contact with Granger and the guy there gave me a hard time about me buying stuff from them as I do not have an account with these people. He asked what the I wanted and stuff took all the details then told me it will take about two days to get an answer on the time price and delivery for me.
I phoned today about it and they have no such information on record about me requesting that capacitor and again they gave me a hard time about me not having an account with them so screw erm!!.
So while we are at it any idea where I can get this part?
Thanks for thinking about me on this problem. Anthony.
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Anthony
Motor start/run capacitors are not unusual parts.
Yours is 18uF 300VAC, if I remembered the label correctly.
A lot of FHP (over 1/4 HP) single phase motors have one.
Any electrical place that sells/repairs induction motors should have a good selection.
Only snag is, they may be different in physical size, making it a fiddle to get them installed sometimes.
Dave BC
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Anthony,
You might check to see if there is a Johnstone Supply Co. in your area. They stock a couple that would work for you. They are 17.5 Mfd at 370 volts or 20 mfd at 370 volts. The higher voltage is a GOOD thing as they don't fail as often. You can also check this link. They sell a 2 pack for under $15. Not sure about the shipping though.
http://store.eurtonelectric.com/370volt.aspx
Hope this helps,
Joe
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Joe.
Thank you for the link. I bought the two pack 20MFD370volt. They are en-rout to me as we speak. Must say the company you recommended was very helpful, polite and quick and was a pleasure doing business with them.
When they arrive I will install them and If I need help I will post. Either way I will post with the result.
Thanks Anthony.
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Ok. So now I have my capacitors delivered to me now my question is I have a red and a yellow wire leading from my old capacitor what wire goes where? Can I get this configuration wrong? If you need pictures please let me know.
Many Thanks Anthony…
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There should be a small bead of solder on top next to the "identified" terminal, line voltage lead will go to that terminal. It has been a long time for me, so verify my info with someone more up to date. On second thought, the identified terminal is connected to the run terminal on the motor. Connecting it backwards can cause gases to build up and failure. of course, if the capacitor is in the start winding circuit, the same applies. Incorrectly and voltage can stay applied to the winding even when stopped.
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Being an AC capacitor it makes no difference which wire goes where.
Joe
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Well guys I installed the capacitor and orientated the pump in the position that it should be run and turned it on and it still gives off a hum and draws current that makes my lights go out. So now what do I do?
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Either the motor has totally karked or there is something preventing creation of the necessary starting torque.
Some motors have a switch that closes when the motor stops and that closes the starter circuit, when the motor begins to spin the switch opens. If the switch fails to close the motor will not start.
So, peer into the end of the motor and see if you can find anything that looks like contacts etc, these switches are often not much more than some bits of bent metal with a light spring attached.
If the spring is broken there is no incentive for the switch to close, if the contacts are burned and not making contact that could be another reason for no starting circuit.
Be careful with the capacitor, it can be charged up to lethal levels!
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Is the motor and pump free wheeling when assembled? I would have to say you have a binding problem somewhere.
Bernd
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Thanks to all again for helping.
John. I will look for the spring switch thing. Great advice about the stored energy in the capacitor. Just what is the right way to discharge the energy?
Bernd. a lot of people have mentioned the same thing. What puzzles me is that when I spin the motor by hand I feel a little resistance but! that’s the bearings, I cant feel lumps or get the rotor stuck.
Thanks to all. Anthony.
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Great advice about the stored energy in the capacitor. Just what is the right way to discharge the energy?
Thanks to all. Anthony.
Simply grab both ends of the capacitor in each hand and it will discharge quite nicely. When you have stopped dancing and the burning smell drifts away you will know that the process has completed ....
Or if you prefer,
Use a wire and resistor across the terminals to discharge the cap. The resistor slows this down to put less strain on things.
The second idea sounds good to me, but the choice is of course yours as always ..... :zap:
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Darren.
Thanks pall I shall try the first idea as a need a different atmosphere in the shop anyways, I am getting tired of way lube and cutting fluid aroma.
:D
If I don’t like the result I should try the second but a resistor is something I may not have but! If I were to carefully short out the terminals to a ground rod I have buried in the shop would that work?
Anthony.
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Well a bit of resistance is the "proper" way to do it, that's why your body works so well.
But then I often am too lazy to go and look for a resistor and just use a piece of wire. Just don't tell anyone or there will be a riot.... :coffee:
You don't need to short it to ground, just across the terminals, just flick it and keep flicking it till the sparks stop. Then wrap some wire around the terminals cos caps can sometimes re-charge a little bit. I say a little bit, it can still hurt.
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There is still a bit we dont know about this problem but maybe this will help us along the way:
Get a mains light globe, put it in a socket and wire it across the capacitor (i.e. one wire from the light socket is wired to one terminal of the capacitor and the other light socket wire connected to the other capacitor). Then try the start again.
If the motor was/is working properly the light will come on briefly as the motor gets up to speed then it will go off. Also, provided the light bulb is good it will discharge the capacitor.
If the starting switch is not closed (as it should be when the motor is stopped) the globe will never light, so that is useful information.
N.B. Take no chances with the capacitor and always consider it charged and lethal to the touch.
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John.
I will do this tomorrow I sent a little drawing of what I think is your idea as to do the light bulb thing.
This way I will have the pump stripped down again and I will probably tear into the bearings and such. But first I will try your idea.
Thank you Anthony.
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Anthony
That won't do anything. The lamp terminals are shorted. It won't light up!
As no-one has posted a circuit of a 'generic' single phase, capacitor start motor, I will e-mail you some info. if you want.
Can't be bothered to post pics. on P-bucket ::) copyright stuff anyway ..
Dave BC
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Anthony
On reflection ...
As this motor was oil-immersed, I doubt if it ever had a start switch. Electrical oil is a very good insulator, it would inevitably get between any start switch contacts, and never start.
Could be a capacitor start/run motor. Fluids take some power to pump, so it adds up there too.
Looking at the pics. it MAY be that the configuration you have is like this:
(http://i359.photobucket.com/albums/oo31/Bluechip_mech/S_PhaseCircuits003.jpg)
In which case you can
Remove the capacitor first, and
Meter, on a low resistance range, between yellow and white. I guess you should get from about 50 to 200 ohms. Typical, not absolute, varies!
This checks the start winding.
Meter between red and white, once more a similar value. They will almost certainly be different.
This checks the run winding.
If one or more of these is a very high resistance, above 1000 ohms or so, that winding is probably done for.
It is quite normal not to see all the connections. They are often done at the end of the windings, then sleeved and buried. Just to make life easy.
Also meter between red and green, must be well above 1Mohms. Ditto white and green.
This does assume that the diag. is OK
It's non-destructive, worth a try, and posting the results.
Bit of practice with your meter .. :thumbup:
Dave BC
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Dave.
I thank you for the little sketch, drawings are always the most important part of any explanation.
Now after reading again John Hills explanation I think as you look at the little crap o cad I got it wrong on what he was trying to get over. My fault not his.
I have printed out your idea and to the shop in the morning I will go give this a shot. your right this is a great chance for me to do a real time experiment with my meter.
I have other questions but I will wait until I give the report on this exercise. Thank you.
Anthony.