Start Capacitors for Champion Air Compressor - I need new ones

[joestewart]

This circa 1976 Champion air compressor has an Ajax 5HP 220V single phase motor, model XIM-5-184T. The motor has two separate start capacitors that are hooked up "in series". The connections are corroded, and I need to replace the two start capacitors. The problem is that the numbers on the old ones are only half legible, and the companies that made them ("Hi-Torq" and "Mepco / Centralab") have long gone out of business.

I think I can tell that the larger capacitor is 710-850 MFD at 165 volts. The smaller one, I think, is also 710-85 MFD (all you can see on the label is part of the "7", part of the "8" and part of the "5"), but I am unable to tell the voltage rating of the smaller one (possibly 125V since it is of smaller size?). The smaller one is a "Hi Torq" part number "CSP708", a number which I have been unable to cross reference using the various search engines.

I have included a photo of the motor, the data plate and the two old capacitors.

My question is: Can anyone recommend the correct replacement start capacitors for my air compressor? Will be forever indebted.

 

[Retired]

Hi,

Do you have a local motor rewinding company you could visit taking along your motor and also the capacitors; if so then the company should be able to sort out the correct capacitors for you by running a dynamic test not costing a lot of money other than for the new capacitors.

I worked for a huge motor manufacturing company it having a number of factories; I worked in distribution/despatch but I picked up lots of motor information. The company manufactured brand new motors but often customers repair motors would be repaired just across the street at a motor repair company and being the nosy type I used to visit the repair company where I often looked over a shoulder gaining lots of knowledge; I did watch such a test where the guy connected the motor to a test board and then he tried a number of different rated capacitors until he obtained the correct readings; the repair took only minutes.

If you don't understand capacitors or electrical work please be extremely careful because mains electricity will kill given chance and to find out the hard way how capacitors hold full charge even with a motor switched off and unplugged will quite literally come as a big shock. Never ever look directly at the capacitor connections with them pointing to your face whilst under power; if the capacitor blows its end out it could blind you in an instant.

Your compressor looks like a lovely restoration project?

Out of interest it's surprising what you can learn by just keeping your eyes open and mouth shut.

My home wound 415V 3 phase 75kg transformer being installed; I've wound many transformers over the years this being the biggest.

Here's my Startrite Volant industrial ten speed bandsaw being phase balanced to the above transformer using a bank of capacitors these being very dangerous so I don't encourage anyone to do such work.

My rebuilt Volant 24" running on home installed 3 phase. A little learning can kill when it comes to mains electricity.



Kind regards, Colin.

 

[thegoodlookingbloke]

This circa 1976 Champion air compressor has an Ajax 5HP 220V single phase motor, model XIM-5-184T. The motor has two separate start capacitors that are hooked up "in series". The connections are corroded, and I need to replace the two start capacitors. The problem is that the numbers on the old ones are only half legible, and the companies that made them ("Hi-Torq" and "Mepco / Centralab") have long gone out of business.

I think I can tell that the larger capacitor is 710-850 MFD at 165 volts. The smaller one, I think, is also 710-85 MFD (all you can see on the label is part of the "7", part of the "8" and part of the "5"), but I am unable to tell the voltage rating of the smaller one (possibly 125V since it is of smaller size?). The smaller one is a "Hi Torq" part number "CSP708", a number which I have been unable to cross reference using the various search engines.

I have included a photo of the motor, the data plate and the two old capacitors.

My question is: Can anyone recommend the correct replacement start capacitors for my air compressor? Will be forever indebted.

Hi, it's a bit unusual to have capacitors in series when there is highis

 

[thegoodlookingbloke]

HI, its a bit unusual to have capacitors in series when there is a highish voltage situation, because if one gets a bit leaky the other one may reach or exceed its voltage rating.
As it's only a start capacitor all it has to do really is give a bit of phase lag on the secondary winding which starts the motor in the correct rotation. So as long as you choose one above the voltage that it might see and one that is designed to handle the power, the capacitance is not too critical.
I would plump for a 400v AC rating and say 32uF and I am sure you will find it works well.
Look on Ebay for 'motor start capacitor'

 

[WyrTwister]

capacitor 850 mfd - Google Search

www.google.com

Think this is one . Not sure about the other one .

One may be a start capacitor and and the other may be a run capacitor . But they would not be wired in series , I do not think . Best to take photos and make notes , before you disconnect wires . Probably too late now .

Does it have a centrifugal switch ?

Redirect Notice

www.google.com

Like diagram (c) .

I agree , best take it to a motor shop .

5hp 250 volt single phase capacitors - Google Search

www.google.com

God bless
Wyr

 

[PatagualFixer]

Sorry, but those capacitor values sound very odd...and in series...? I cannot see that.
Given the photos...Mmmm
Someone mentioned an inertia/centrifugal switch, that's a real possibility.
I have a swimming pool pump that has one.....
It's 20 years old and has been underwater many times in our rainy seasons.....
(when I forget to remove it for the winter season.! DOH!)...
But... Prior to the season, I remove the end bearing cap and clean the contacts & lube the mechanism.
It's Brazilian made, to a US design (I imagine) ...from an era we all made stuff ... "So much better & with pride."
I imagine many unemployed in the USA are questioning the same situation.
Why don't our politicians listen? I don't want to bring politics into this site...it's "not the place"...
But how much longer is this ridiculous situation going to go on?

 

[WyrTwister]

Electric Motor Starting Capacitor Selection Select an A/C Compressor & Other Electric Motor Start-Boost Capacitors

inspectapedia.com

Chart on this link lists a ball park value of 750 mfd for start and 30 - 40 mfd 370 volt for a 5 hp motor . I suspect this is for 240 VAC , single phase . Three phase motors commonly do not use capacitors .

God bless
Wyr

 

[carogator]

Champion Air Compressor Replacement Parts & Manuals

www.industrialaircompressors.biz

 

[Retired]

Hi,

joestewart is correct when he states both capacitors are in series; here's more Ajax information; it's a different motor but clears up the capacitor connection issue; I've never seen a motor previously with series capacitors and I've been watching this thread with interest; unable to find the correct motor just meant searching a bit more for information;

http://vintagemachinery.org/photoindex/detail.aspx?id=21630

Depending on supply voltage these capacitors can run either series or series/parallel. If there is a centrifugal switch then normally this drops (disconnects) a start capacitor offline once the motor comes up to speed but allowing the run capacitor to remain online; it would only be guessing here on the forum without actually handling the motor. As I said earlier the quickest and best solution is to visit a motor rewinding company taking along the motor; one thing I do know about capacitors is they can't be trusted and even new off the shelf when tested could give a totally different reading than stated on the capacitor; I've restored over 100 vintage valve radio sets and given their old age first job without even checking was to replace the capacitors then check the resistors; the old resistors used to go well out off spec once they had been stored for years even without being installed into a radio.

I doubt very much this motor in question is fitted with a centrifugal switch because the capacitors are controlled by the wiring connections depending on supply voltage used?

Due to safety reasons I'm always very careful when replying to an electrical question assuming if something can go wrong it will go wrong and no way do I want to injure anyone.

Kind regards, Colin.

 

[piglet11]

Take note of all the advice on safety. Capacitors can get up to voltages much higher than the nominal voltage, like 240-volts mains peaks at about 320-volts and that would hurt.
Avoid cheap large capacitors.
As with any components, there are many fakes on the market.
I was watching a video on someone testing capacitors marked at 63-volts, but were actually 35-volt. They burst into flames at 55-volts and destroyed the circuit. The only clue was the dodgy printing and a red dot that someone had added
Capacitors need to be rated for the highest voltage they will see plus some more.
Try some of the component distributors like Farnell and RS who only deal with reputable suppliers, or as others have suggested, a motor specialist.
I expect Colin has seen the blue smoke of death more than once.

 

[Retired]

Hi,

Many thanks piglet11. Yes indeed lots of bangs and blue flashes as I've played around in my workshop but when working on something new to me I'm well clear when I throw the power switch; even a small capacitor can cause serious injury if it explodes; during my radio restoring days many fellow restorers used to "reform" their electrolytic capacitors; I never bothered just cutting the cans open and replacing the duff capacitor with a modern top quality capacitor then sealing the can.

My latest fun with exploding capacitors was when I tried TIG welding for the first time when the welder expired in style with a big bang filling the workshop with a dense cloud of smoke; the welder was located about three feet away behind me and it got my full attention.

When these capacitors exploded they also took out three very expensive circuit boards but the welding company were absolutely brilliant in repairing it totally free of charge and now it's a lovely welder.

Kind regards, Colin.

 

[piglet11]

Cheers Colin
Despite years of working with electrics and electronics, I still get caught out.
I recently replaced a contactor on a water heater.
It was double pole so should have been totally isolated on the load side.
What I didn't spot was the capacitor-resistor spark quencher across the contacts.
Another lesson learnt.
The worrying thing is the quantity of cheap electrical goods on the web, especially things like power supplies and chargers.
They are cheap for a reason and not a lot gets saved if the house goes up in smoke as well.
The problem is that once reputable manufacturers now cut costs by buying in gear rather than manufacture.
However, I mustn't grumble as the Chinese stuff isn't all bad and has saved my bacon more than once.

 

[Retired]

Hi,

Yes it's so easy to get caught out on electrics piglet11; the only snag with mains electricity being caught out just once could be the last thing ever done it doesn't take prisoners. I don't recommend it but an insulated handled screwdriver put across wires or connections will son prove if a circuit is dead; better blowing a lump out of a screwdriver blade than being electrocuted; the safest way is to take voltage readings with a DMM.

Made in China used to be a joke but I think it's gradually turning that Made in Britain is now becoming the joke? Who is to blame most the manufacturer trying to make a profit whilst being badly squeezed by the buyer who these days wants something for nothing. Lots of good stuff now comes out of China which is just as well because we manufacture so little; our largest growth industry are fast food outlets.

The tool and machinery market in America is vast compared to our little island; everything is expensive here; I used to visit Bardwells Electronics in Sheffield buying components at rock bottom prices but now Bardwell's have closed it costs a lot more on the web for similar components; Maplins used to be good but in later years they concentrated on selling things with flashing lights and virtually gave up selling components; the reason for this being no demand for components other than from the older generation; young folk these days don't want to do anything useful.

I did the full routine; pedal cycle; work up through motorcycles until I had a 1,000cc bike by the time I was 18; then move over to cars and vans; we currently run a lovely diesel Skoda Yeti which is a keeper but I'd love to buy a new Tuk-Tuk pick up truck just for the fun of owning it and for carting stuff around locally.

Kind regards, Colin.

 

[piglet11]

Thanks Colin
I do have a healthy respect for electricity and did a lot of work on three phase, large pumps and compressors. With an implanted cardiac device, I'm extra careful, but you know how it is, double pole....
Fortunately the suppressor resistor limited the current and I never work two handed. Got all the gear, so no excuses.
The Americans still have that "can do" and "make it" attitude and that I admire. I have a sneaky desire to own a John Wayne Winchester, but it won't be in this country.
Maplins were useful, but as you say, got into too much Xmas tree stuff.
On tools, for years we were probably ripped off on prices. I did notice your Startrite and thought there's a proper band saw.
I like Taiwan stuff as they are engineers. The Chinese are copiers, but very industrious. In high tech, they are streets ahead of us and almost all PCBs and high tech components come from them. They do to good advantage what we gave up on.
I don't like Dyson because of that. Made a bit of money here then went offshore.
So far I haven't found anything I can't source from China, but some of the prices are ridiculously low.
Yes, we have given up on the harder science and technology careers, but there is still a thriving community of all ages doing electronics and coding (programming) - Arduino is an example.
The trouble is, you can't make a living making robots, which is what they teach at school to keep kids interested.
For components, I still get a lot from RS, Farnell, Rapid and many of the ebay suppliers.
We've recently seen with the virus PPE fiasco what can happen if you price out the domestic manufacturers. Can't make masks or gowns? Ridiculous. Some NHS manager must have what a good idea it was to get the stuff cheap. UK firms go out of business.
One really good proper UK firm I will mention that might be of interest is R H Nuttall who do every gasket under the sun. A family business through and through and superb customer service.
These days, I'm having a second childhood. As a kid, if it moved I made it, if it lived in a stream, I probably caught it.
So model railways, planes, boats the lot, plus the goldfish.
Vehicle wise, much the same course as you. Still biking (pedal) with the fractures to prove it. Ford Prefect through to current VW Caddy van, my shed on wheels.
Good luck with the Tuk-Tuk. Plenty in Brighton near me and a neighbour used one as the wedding car. NSU Quickly moped would bring back a few memories.
Keep safe. One thing I bet, is you never get bored and are better for it.

 

[joestewart]

Thank you for all these helpful replies.

The Champion parts book: I don't think it will help me because I doubt that this this electric motor was fitted at the factory.

Yes, this machine has two start capacitors hooked up in series. I was able to purchase a Hi-Torq CSP708 start capacitor. I have included photos of the start capacitors that I bought and a photo of the installed capacitors before I clamped them all in their proper places. When I applied power to the circuit, the motor started and ran, but it was making a high pitched whine. I will next replace the two "run capacitors" and see what happens.

Thank you for the warnings regarding the safe handling of capacitors. I was aware that they stored a charge, and was informed that the two poles should be short circuited (as for example with a screwdriver) prior to handling in order to dissipate any stored electricity.

I will investigate the possibility of bringing it to a shop that rewinds electric motors, but the charge for the service may exceed the value of the compressor. I will find out.