Questions & answers on how to choose the right replacement motor start or run capacitor.

This article series explains how to choose & buy an electric motor start capacitor, hard start capacitor, or run capacitor that is properly rated for and matches the requirements of the electric motor such as an AC compressor motor or fan motor where the capacitor is to be installed.

FAQs About Motor Starting Capacitor or Run Capacitor Replacement

Recently-asked questions & answers about how to select the proper start or run motor capacitor posted originally at CAPACITOR SIZE DETERMINATION for ELECTRIC MOTORS - be sure to review that article.

On 2022-06-10 by InspectApedia-911 (mod) - Doerr Electric Motors started in the early 1940s

@Curtis Pieratt,

OK so on that Doerr 1HP motor you have the data you need to follow the generic start/run capacitor selection guidelines above on this page.

Doerr Motors was a brand owned by Grainger, an electrical supplier, so you could also call Grainger directly, giving the model number Doerr Model No. LR22132 to ask for help choosing the capacitor that you need.

Grainger: Website: https://www.grainger.com/
Customer service: 1 (800) 472-4643

For other readers, here's a

Tiny history of Doerr Electric Motors.

Doerr Electric Motors was founded in the U.S. in the very early 1940s, originally using the name Electro Machine Corporation, in Sturgeon Bay, WI, Cedarburg WI, and Burr Oaks, MI. Doerr was acquired by W. W. Grainger, Inc., July, 1969.

These motors were used on various equipment including air compressors and other metal machine and woodworking machine tools including some sold under the Delta brand.

Grainger sold its Doerr line to Emerseon Electric who sold Doerr on to NIDEC. Some older Doerr electric motor manuals might also be found at Leeson's website, leeson.com.

Current (2022) contact for Nidec is given below but we note that the company's website doesn't even mention the Doerr motor brand directly, referring readers to U.S. Motors. .

• Contact: Nidec Motor Corporation Headquarters, 8050 West Florissant Avenue, St. Louis, MO 63136 USA, Tel: 1-888-637-7333 Web: https://acim.nidec.com/motors/contact-information
• Contact: Leeson Electric Motors, Web: https://www.regalrexnord.com/brands/leeson
  
  Regal Rexnord Australia 19 Corporate Avenue Rowville, Victoria, Australia 3178 Phone: +(61) 3 9237 4040
  
  Regal Rexnord Canada 320 Superior Boulevard Mississauga, Ontario, Canada L5T 2N7 Phone: 1-905-670-4770 Fax: 1-905-670-8971
  
  United States Customer Service: 1-833-734-2500 Regal Rexnord Corporation 200 State Street - Beloit, WI 53511 Phone: (608) 364-8800 Fax: (608) 364-8816;

On 2022-06-10 by Curtis Pieratt

Missing cap.
Doerr 1 hp 60hz
FR - J56
115 lo volts 17.6 FLA /AMPS
3450 rpm air compressor.
Single ph. LR22132 type k
OTHER #s (M06026 ) MTR.R.REF -(R604933CF813 ) :)?
Ser fact. 1.0
Duty - cont.

On 2022-04-01 by Inspectapedia Com Moderator

@Ian Breeze,

Have you looked through the instructions above on this page on how to make a reasonable guess at the proper capacitor for your motor?

On 2022-04-01 by Ian Breeze

I have exhausted all avenues to find this capacitor please help!

On 2022-03-22 by Inspectapedia Com Moderator - British Horse Power (BHP) OR Horsepower (HP) OR brake horsepower (bhp)?

@Dave,

Looks as if I've got confused and so been confusing.

1 bhp - 0.745699872 kW.

So your 747 Watts per bhp is correct.

Standard definition:
British Imperial System: one horsepower (hp) equals 33,000 foot-pounds of work per minute—that is, the power necessary to lift a total mass of 33,000 pounds one foot in one minute.

However, BHP (British Horse Power) and "Horsepower" are not necessarily identical.

And even the acronym "BHP" has more than one definition: "British Horsepower - BHP " and "braking horsepower - bhp"

Adding to confusion is the term "Boiler Horsepower" and also Metric horsepower.

In the UK people use "brake horsepower" to measure the horsepower of a vehicle or its engine, expressed as bhp. Brake horsepower or "braking horsepower" is the most common measurement of engine power.

HP or "horsepower" of an engine will be slightly higher than bhp because hp doesn't take into account the frictional losses within an engine.

Wheel horsepower or WHP takes into account additional losses in the drivetrain in delivering power to turn the wheels of a vehicle and thus to move it on the road surface.

On 2022-03-22 by Dave

In your response to Aiman below, you said

" On 2021-09-27 by (mod)

@Steven,

In general,

"1 bhp or horsepower = 1.341 kw."

Now I'm confused. I thought for every horsepower there were 746 Watts. Is bhp different than horsepower?

On 2022-02-19 by Inspectapedia Com Moderator

@Tommy Sweet,

Above all this page there are tables of start and run capacitor sizes for motor sizes when we don't have data tag information. Please take a look.

On 2022-02-19 by Tommy Sweet

I have a 5 hp Baldor compressor motor that I need to know what capacitor. I am having a hard time finding, can you help? 230 volt.

On 2022-02-08 by Inspectapedia Com Moderator - is it a capacitor or the motor failure?

@Tom,

By its data tag, your motor, when running, draws 34Amps. It will draw higher amps for a moment during motor start-up.

A 50A generator should have not trouble powering that motor provided that the wire lengths between motor and generator are not so long as to cause a significant voltage drop and provided that the generator isn't also being asked to power many other devices at the same time.

Therefore I suspect that the underlying problem is

- a bad starting capacitor for the motor (try replacing it)

or - more-likely -

- a motor or motor-bearing failure that is causing the motor to draw abnormally high current.

On 2022-02-08 by Tom

I am having trouble running my 230v motor off a 50amp generator. There is nothing wrong but the in rush keeps popping the fuse. When I bought the knife sharpening machine it was hard wired into the garage and worked great. My friend that’s an electrician said it’s pulling 90amp for the start up, single phase.

I attached a picture of the plate and I and wondering if I can add a start capacitor and maybe also a run capacitor but I have no idea which ones to buy and the century factory is trying to sell me a new motor for 2000 dollars. Please anyone who can help?

On 2021-11-14 by Inspectapedia Com Moderator - start and run capacitor sizes tables

@Dhsebra,

Above all this page there are tables of start and run capacitor sizes for motor sizes when we don't have data tag information. Please take a look.

On 2021-11-14 by DHSEBRA@AOL.COM

I am looking to find the Micro freid rating for a duel start Capacitor for a 10 hp single phase marathon motor. the run caps are 20 micro freid duel start and duel run caps.

What size start capacitor do I need for a 10 ho single phase motor using duel start and duel run caps mine have no markings ???? Please let me know

On 2021-10-23 by inspectapedia.com.moderator (mod)

@Adam,

Sure, just take a look at the capacitor selection guide above and you'll see that there are several ways that you can make a reasonable guess at what capacitor you need. You'll also see that you can use a close match; it doesn't have to be an exact match.

On 2021-10-23 by Adam

Having difficulty finding this capacitor for my old car lift it is a 2 post screw lift rated at 6,000 LBS has somewhere between a 1/2hp to a 2or 3 HP motor a chain runs underneath that keeps the two posts in sync runs on 240v 1 phase. Can anyone help

On 2021-10-15 by (mod)

@Aiman,

Look at the specifications on the motor data tag.

Some capacitors combined start and run in one physical device. Look at the terminals.

On 2021-10-15 by Aiman

3hp sgle capacitor

I want to know uf for my air compressor please help me.

On 2021-09-27 by (mod)

@Steven,

In general,

1 bhp or horsepower = 1.341 kw.

1/9 hp x 1.341 = about 0.150 kw
Or about 150 watts

On 2021-09-26 by Steven

Hi i saw in the web site that my fridge compressor is 1/9hp but in ur chart is in kw..how do i know the right cap based on ur list u have given?

On 2021-09-14 by (mod)

@Ilias

We have added several tables and notes detailing pretty-much all of the codes and markings found on capacitors - now in the article above. Thank you for asking.

You may need to clear your browser cache to see the updated page.

On 2021-09-13 by (mod)

Re-posting without link - for reader security

ILIAS BURKETT · 5 hours ago
I am just beginning to learn about Refegerators/Freezers. There seems to be some Markings/Numbers on the start Capacitors other than Capacitance(uF), &, Voltage. For example, there are some numbers like this "25/70/21 PO". I am not sure what these numbers mean? Also, some Capacitors have more than one Voltage ratings(h/cl.b & h/cl.c). As an example, here is a link for a start Capacitor listed on ebay;

On 2021-08-23 by (mod)

@Mac,

Above on this very page you'll find tables and suggestions for sizing motor capacitors based on motor size (1/5hp in your case) and type. Please take a look and let me know if that leaves you with questions.

On 2021-08-22 by Mac

I have a air handler fan motor that is needing a new capacitor. The markings are not legible for mf. The motor size is 1/5 hp. Any help is appreciated.

On 2021-08-08 by (mod)

@Peter,

I think at this point our best bet is to take a guess using the capacitor size table versus motor horsepower given in the article above.

On 2021-08-08 by Peter

I've an old Crompton Parkinson motor on an air compressor and the capacitor seems to have packed it in. I've attached a photo of it but as you can see the specs are unreadable. Looks like it has a max of 150 F? The specs on the motor are Model PA9342Q-P-M running at 50Hz 1.5HP Class E Amps 7.8 9.0 240v. Could you advise please? Peter

On 2021-07-21 by (mod)

@david carson,

Our electric motor starting capacitor sizing tables don't address much higher horsepower motors like your 20HP motor;

First, are you sure that your motor uses a starting cap?

Second: have you checked the specifications on the motor's data tag or in its IO manual?

Alternatively sciencing.com offers this formula that we've not confirmed

"Multiply 0.5 times the square of the voltage. Call this result "x.". Continuing the example, you have 0.5 times 11.5 volts times 11.5 volts, or 66.1 square volts for "x". Divide the start-up energy requirement, in joules, of the motor by "x" to arrive at the capacitor size needed in farads."

On 2021-07-20 by david carson

I have a 20 horse motor what starting capacitor did I need and how much

 

On 2020-12-07 - by (mod) -

If I understand the question it's about how the wires connect to the terminals on the capacitor; Most use a push-on spade-type connector, but in any event the connector type won't affect how the capacitor works.

On 2020-12-07 by Kevin

Thank you again.

Sorry - last question: Any suggestions on what to do about the difference in terminals between the ICQUANZ and the existing start capacitor?

On 2020-12-07 - by (mod) -

A failing bearing can sometimes be detected by simply noticing that the motor is hard to turn manually when the power is off. You wouldn't stick your fingers in there with the power on.

On 2020-12-07 by Kevin

Thank you for the quick reply!

We have that capacitor on Amazon Canada. But the terminals I need I think are quick connect terminals. I have three wires that attach to the capacitor and I'm not sure how that would work with this capacitor (https://www.youtube.com/watch?v=3nJjFK6qcHk).

There is no run capacitor in the food processor, just the start cap and the AC motor really. Apologies but what would a failing bearing look like, which I presume is in the motor? I presume if the motor is kaput, it's time to buy a new food processor. And why would there be low voltage as an alternative?

My sense is that this all started happening after working the processor too hard.

On 2020-12-07 - by (mod) -

Kevin

If the motor starts rather than humming the start cap may be OK, but there could still be a bad run cap (if there is one) or a failing bearing (most-likely) or even low voltage, and occasionally a winding that opens when the motor speeds up.

I'd get as close as possible to the original cap and give it a shot.

You shouldn't have any trouble finding a 150 uf Capacitor - one is shown below from Amazon

On 2020-12-07 by Kevin

I'm searching for this Whirlpool motor starting capacitor #8211608 used in a Kitchenaid Food Processor KFP1322ER0. The food processor blade spins, but not with the same speed and a humming sound is especially obvious at low speed

. I'm assuming it's the starting capacitor but not certain. Not sure what other explanation there might be. Don't see any other capacitor in the motor assembly. And I can measure the starting capacitor's capacitance easily enough to see if it matches its rating.

Assuming the problem is the capacitor, the problem is this starting capacitor is no longer available, but I did find this picture with the technical specs on it attached below. So its capacitance is 150 MF, rated voltage is 125-185 VAC, and capacitor frequency is 50/60Hz.

I've been able to find other motor starting capacitors on Amazon Canada but nothing that matches exactly. Based on your great detailed explanations, beyond physical size which seems similar, I can find the following capacitors:

* 161-193 MF (range slightly higher than you're suggestion of +20%), with voltage of either 125VAC (SeaKnight)

* 161-193 MF, 220-250 VAC (Packard)

* 145-174 MF (so slightly below the 150 MF of the original on the low end), 110-330 VAC (NTE Electronics)

* 145-175 MF, 330 VAC (Packard at 4x cost of the NTE capacitor)

* 124-149 +/- 5% MF, 330 VAC, 50/60 Hz (Packard)

Would any of these 5 work well? It seems like the MF is the bigger constraint, with nothing fixed at 150 MF. The ranges either fall ~5% below on the low end or > +20% MF rating (~35% above actually) on the high end.
Also I'm not able to confirm that all would be 50/60Hz. Is that a problem?

Any help would be appreciated - thank you.
Kevin

On 2020-12-07 - by (mod) -

you'll see a capacitor size selection recommendation table in the article above please take a look and let me know if any of that leaves you with questions

On 2020-12-07 by vijendra

my motor is 1hp ,1400rpm, 0.75kw, voltage 220,which capacitor use

On 2020-11-27 by John wilson

I need start capacitor info for 5 horsepower motor on turret lathe bc loss of 3 phase power any help will be appreciated.

On 2020-10-01 - by (mod) -

In the article CAPACITOR SIZE DETERMINATION for ELECTRIC MOTORS we have some suggested starting points for capacitors for electric motors of different horsepowers or sizes period of course the correct and best solution is to obtain a start or run capacitor that matches the specifications on your electric motors data tag.

On 2020-10-01 by M.SRIDHAR goud

Can I use 12mfd for 1/2 hp motor

On 2020-09-28 - by (mod) -

Indeed, Mark, a humming electric motor might get running again with a hard-start capacitor but quite often the root problem is a failing bearing that means the motor's future life is going to be short.

You can tell if it's a start or run capacitor by the general ohms range as you will see in the article above. A run cap is always much smaller in ohms rating than a start cap.

If you can find a properly-sized capacitor you don't have to mount it inside the housing if you can connect its leads to the proper points, just as you suggest.

I can't quite read the label on your device but it looks like 0.1 uf 225V but there ars some other ratign data as well - maybe temperatures?

There are hundreds of electric motor capacitor vendors, both local in most cities, and online, as well as the big boys like Grainger who have almost everything.

On 2020-09-28 by Mark

My Northern Tool Ironton utility transfer (pony) pump had it's capacitor die (motor hums, but doesn't turn. Water got into the electronics housing I think.

It was a great pump (I bought an Everbuilt from Home Depot that looked the same, but the pump housing was plastic and it seems to foam my pool water, where the Ironton didn't).

I believe this is a running capacitor with thermal protection, see attached.
It says X2, which seems hard to find. I believe I still can solder (used to do surface mount stepper ICs back in the day when hard drives were repairable), so was wondering where to find a replacement.

On 2020-09-21 - by (mod) -

Anonymous

Unless I misread something that looks like an exact replacement. The only differences 3 placement capacitor is more precise or headless variation from its standard rating than the original.

On 2020-09-21 by Anonymous

Hi, I'm trying to replace a 40.0 MFD +_ 10%, 370 VAC 50\60 hz 10 000afc - 70c
the only thing I found on amazon is

40uf +- 6% 370v 50\60hz 10000afc

Am I ok with this as a replacement for my pool heater?

On 2020-09-14 - by (mod) - Old capacitor on 240v motor was 125v 150uF.

Mike

Thank you for the added information. I may still be a little bit in the dark on this but it sounds as if all you need to do is wire the replacement capacitor and find a safe place to mount it outside of the motor since it doesn't fit inside. The capacitor can be anywhere close to the motor, of course keeping your wires as short as you can.

On 2020-09-14 by Mike W

Thanks for your reply. Apologies, my question was not very clear. Old capacitor on 240v motor was 125v 150uF. The 250v 150uF I bought is too large to fit in housing. Question - is original capacitor rated at 125v okay to be refitted on motor driven by 240v line voltage?

My logic is that as no 250v rated capacitor that I have been unable to find will fit in the housing then 125v rated cap must have been correct in first place
Mike W

On 2020-09-13 - by (mod) - refurbishing an old (about 40 yrs old) press drill.

Mike

ON the capacitor body you'll see a voltage range like the one you cite - 250v 150uF start capacitor. - that 250-V is the maximum voltage the cap can handle; you're OK using it at lower voltage that matches your motor's data plate.

On 2020-09-13 by Mike Williams

I am refurbishing an old (about 40 yrs old) press drill.

The electric motor is single phase and runs off 240v. It was fitted with a start capacitor with a rating of 125V and 150uF. The drill has had a previous restoration and the capacitor did not look original.

Unable to test the capacitor other than the motor starts okay I decided to change the capacitor. Concerned by the voltage rating of the existing capacitor (125v) and not knowing if it was correctly replaced by the previous restorer, I erred on the side of caution and purchased a 250v 150uF start capacitor. When it arrived it was too big for the capacitor housing.

On further investigation I have been unable to source a 250V capacitor with dimensions that would fit the capacitor housing. Reading this page, I have learned that the capacitor voltage is not necessarily linked to the line voltage but to a voltage derived from the windings. Does this mean that the 125V rated capacitor is likely to be the correct capacitor for a 240v motor?

On 2019-10-08 by (mod) - how to convert a 3 phase motor to run on single phase power

Mogamat

It looks as if your motor runs at 220 or 380 Volts 3 phase and at 220V runs at 16.5A while at 380V it runs at 9.6A.The CAV (short for cavalli or horsepower) on the data plate of this Italian motor from Tavernelle indicates that it's a 5.5 hp motor.

Typically the run capacitor on a 5 hp. motor is around 30 µF - 40 µF 370VAC

Typically the start capacitor for a 5 hp motor is around 600uF

To take a stab at answering "how to convert a 3 phase motor to run on single phase power" I found a variety of answers ranging from "it's easy" to "it's a really bad idea, even dangerous".

Kemet (cited in the guidebooks given in the article above) notes: By connecting a capacitor to the two phases it is possible to make a three-phase motor work as a single-phase motor.

Watch out: you cannot simply hook up a 3 phase motor arbitrarily to single phase current; you need to review the wiring recommendations from motor companies or engineers.

Options include:

A phase shift capacitor;

Motor re-winding

Using a VFD or variable frequency drive

Use a converter to convert your single phase power to DC (Direct Current) and then use an inverter to power the motor. From what I read this is your best bet. As one EE notes "You can run a three phase motor from single phase by converting the single phase AC-DC(rectification) and then DC-AC(3 phase inverter)."

However pretty much everyone says this is an inefficient way to run a motor - i.e. your electric bill will be higher than necessary.

On Quora a Bombay writer recommended:

Use capacitor of say 36 / 72 / 108 mfd 440 V rating. depending upon motor rating. Connect one end of this capacitor to open unconnected terminal of motor.

The other terminal of capacitors can be connected to one of the two live phases, and the motor will start running. If you change over the capacitor terminal to other phase , its direction of rotation will get reversed.

This system is routinely used in India particularly in rural areas for running of pumps.

This arrangement is certainly not the optimum for the motor, and the phase difference between the windings will differ from 120 degrees needed. However, this does makes the motor start and save the day for farmers when 3 phase supply is not available. - www.quora.com/How-do-I-run-a-3-phase-motor-in-a-single-phase-line-using-a-capacitor

See www.gohz.com/3-phase-motor-running-on-single-phase-power-supply

See this article by Chuck Yung www.plantengineering.com/articles/how-to-properly-operate-a-three-phase-motor-using-single-phase-power/ on running a 3-phase motor on single phase power.

Note that operating the motor on single phase may be expensive.

On 2019-10-08 by Mogamat

Good day. I have 3phase compressor that I would like to run on single phase current... What size capacitor would I need and will it need a run cap as well?

On 2019-09-30 by (mod) - be sure you're choosing the right motor starting capacitor

Don,

Here are specs for a small electric motor starting capacitor - this one sold by repairclinic.com

This is a 250 uF starting cap good up to 250VAC 50/60 Hz - your macerator pump motor may need a higher capacity or voltage unit than this;

Have you checked the data tags or capacitor specifications in the manual for your macerator (sewage grinder pump) ?

I don't have authoritative data on capacitor defect occurrence rate for new caps such as you described.

But something doesn't smell right in your capacitor selection.

You say it's an electric motor STARTING CAPACITOR RATED AT JUST 10uF [and 450v) but 10uF is awfully low for a motor starting capacitor.

For example over at Grainger - one of the biggest suppliers - their electric motor starting capacitor guide doesn't even go that low.

You are describing a motor in a macerator - perhaps what is also called a sewage grinder pump? - if so, again I'm doubtful about that capacitor selection.

Over at Grainger.com you'll see that a Dayton brand 10uF 450VAC capacitor sells for under $10. in the U.S. - under £10 - AND that such caps in that range are labeled as motor RUN capacitors NOT as start capacitors.

IF your start cap was not properly sized that could explain why it keeps blowing. Is it possible that the labeling on the original motor start cap was blurred or damaged or mis-read?

Below is a 250 uF starting cap good up to 250VAC 50/60 Hz - your macerator pump motor may need a higher capacity or voltage unit than this;

Have you checked the data tags or capacitor specifications in the manual for your macerator (sewage grinder pump) ?

In sum, for various types of pumps and motors of similar sizes such as residential macerators or smaller sewage grinder pumps a typical motor capacitor set might be

Start Capacitor # 005290115; Start Cap Rating 233-280 MFD, 220V

Run Capacitor # 122670021; Run Cap Rating 15 MFD, 370V

Watch out: Be sure to see the electric motor capacitor selection tables given in

1. The data tag on the electric motor itself
2. The manual for your specific motor or appliance
3. or for a general guide CAPACITOR SIZE DETERMINATION for ELECTRIC MOTORS

On 2019-09-30 by RonDobson - start capacitor EBB60 10uF 450v keeps blowing

I have a cheap-make macerator where the motor has a start capacitor type EBB60 which is 10uF 450v. It got jammed with a tampon and blew the capacitor (loud humming noise), which I replaced with an EBB60 bought from Ebay. This worked fine for a month, then went again.

Bought a similar one from same source which worked twice (i.e two flushes) followed by a loud humming. Could it be a bad batch from Ebay?

The caps cost £6, and I notice Saniflo sell one for around £25.

Would a better quality capacitor - assuming the more expensive one IS better quality - work?

On 2019-08-25 by (mod) - Capacitor for home made air compressor motor: Egido Colombo IME Motore Asincrono Monofase

That is a 16 uF 42-50Hz 280V capacitor produced by Facon - a Chinese manufacturer of capacitors, though your particular capcitor No. 6912 indicates that this Facon cap was produced in Italy.

Details are in CAPACITOR SIZE DETERMINATION for ELECTRIC MOTORS

On 2019-08-25 by mick

I have had a capacitor blow on my home made compressor which my Dad made many years ago so has great sentimental value

i use it but have had this capacitor blow and would like to repalce it. it has an italian motor on it and the make of cap is FACON

but i am having problems tracking down a repacement can i just replace the one thats blown or would it be wide to repalce both sorry to show my ignorance

but i have no clue to whatthe middle one is i am assuming it could a starter cap? thank you in advance mick c

Below: the data tag from Mick's air compressor motor shows its a 1 horsepower 230VAC single phase 10A motor that runs at 1450 rpm.

On 2019-08-25 by Anonymous

could anyone please help me in selecting the correct capacitor to replace the blown one in pic or would it be best to replace the lot

On 2019-01-18 by (mod) - try replacing the start capacitor before replacing the entire well pump

Org

The cost to try a new capacitor is trivial so sure go ahead and try it.

However if the underlying problem is a failing pump motor, a new starting capacitor will give but short term relief. So be sure you can exchange the pump within warranty period if needed.

Before replacing the motdor capacitor you have shown, why not test it to see if the problem is there or elsewhere.

See TEST a MOTOR START or RUN CAPACITOR for details.

Watch out: if you are not trained in safe electrical wiring and work you could be shocked or killed.

On 2019-01-18 by organizome49

I have a 1hp water well jet pump (115vac, 11 amp) with a startup capacitor that is beginning to fail. Its 10 months old with a one year warranty, I'm sure it the capacitor because the motor struggles to startup after cut-out and will struggle to restart.

So far it will eventually restart and runs well when it does restart but the condition is getting worse.

I was told by the supplier I can return and exchange the whole unit, a major undertaking. I was thinking that I could replace the capacitor and that would resolve the problem.

I've included an image of the capacitor markings and would like your input on finding a replacement.

The unit was made in China for Tractor Supply Company. Anything else you could tell me would be appreciated. Thanks.

On 2018-12-29 by (mod) - shaper motor that loses power

Thank you for an interesting question Bill.
Anon
I would check the supply voltage to make sure that that's normal. Then I suspect that there may be a problem in the motor itself such as a failing bearing that could be causing the motor to draw High current.

I don't think that a bad start capacitor would cause a motor to slow down and draw High current under load.

On 2018-12-28 by Bill

I have a shaper motor that loses power on running a board down it. It will kick the breaker. I did a meter test on start up and running and it was showing 21 amps. The plate says 115 volt and 8.5 amps. Is this stuck in capacitor start winding?

On 2018-12-17 by (mod) - Plessy brand 100 uf stdarting capacitor substitutes ok

The Plessy brand capacitor whose imprint I can read is a 100 microfarad starting capacitor.

You don't need to replace it with the same brand but just with the equivalent rating.

Notice also the voltage rating and other specifications on your AC Motor Starting Capacitor. 350V RMS Surge, 439/1/90035/100 where the last 100 = 100 uf

On 2018-12-17 by Jon Compton

I’m needing help identifying these.

I’m needing help with this capacitors.

On 2018-09-19 00:40:16.707392 by (mod) -

Normally no.

Watch out: as a general rule of thumb, electric motor start capacitors can be replaced with a micro-farad or µF or mfd rating equal to or up to 20% higher µF than the original capacitor serving the motor. On the replacement capacitor the voltage rating must be equal to or greater than the original.

On 2018-09-18 by Dave C

My air handled blower motor run capacitor is 15uf 370V, would anything be gained by going to a larger capacitor, say 20uf 370V?

On 2018-09-01 by (mod) -

You're Right, Dan.

When a page at this website accumulates a large number of comments I move them to a separate FAQs page. I don't delete them I move them.

The FAQs page for this article is listed in the article links as

CHOOSE a START RUN CAPACITOR FAQs

I appreciate your asking and I'll be careful to make finding those older faqs more obvious.

We don't delete any reader-posted comments except for foul language or someone's effort to post an advertisement.

On 2018-09-01 by Dan Jacobson

Older comments get deleted here I find.
What if one was in the hospital and didn't have a chance to read your reply?

On 2018-08-17 by (mod) - electronics suppliers selling capacitors online

Lawrence

There are so many (more than 1000) electronics suppliers selling capacitors online that I have not tried to make a directory or list. You will also find capacitors immediately available at your local electrical supplier and typically at HVAC suppliers who sell repair parts for air conditioning and heating equipment.

Grainger is a major online vendor.

On 2018-08-17 by Lawrence

Searching for a capacitor
Where are the suppliers

On 2018-08-08 14:43:31.957598 by (mod) -

S.C.

Forgive me but do you first want to diagnose the cause of the hesitant motor-start? If replacing with the OEM capacitor rating leaves the motor misbehaving I suspect there is an underlying problem ranging from a loose wire or connector to a failing bearing or winding, or even an external problem: some motors have trouble starting against an un-intended physical load.

On 2018-08-08 13:02:42.984562 by S.C.Mittal

I am using a capacitor start and run induction motor monoblock water pump rating CONT, 0.37kw(0.5 hp) 230 volts 50 hz current 2.6 amps with original capacitor of 10 microfarads but sometimes the motor starts after switching on 3-4 times. Please inform what rating capacitor should be replaced to get smooth working and if higher rating capacitor is used will it harm the motor in any way.

On 2018-07-26 13:35:46.775436 by Wayne

I replaced the duel capacitor and put in a new condenser fan. The fan hums and will not start in the beginning. If I give the fan blades a push it will start and stay running and cool the House. What is the next issue I should look for with the condenser fan not starting.

On 2018-07-19 23:03:11.224006 by (mod) -

Be sure to see MOTOR CAPACITOR WIRING GUIDE at https://inspectapedia.com/electric/Starting_Capacitor_Wiring.php

On 2018-07-19 13:43:21.249385 by Ron

Hi, neither the old or new run capacitor have + or - markings on them. Does it matter which wire goes to which terminal?

On 2018-07-05 by (mod) - You can safely go about 12% over original capacitor rating

You can safely go about 12% over original rating, Peter so I'd guess 15uF is ok.

But I suspect the problem is a different one: the wrong pump for the application, or pump clogging, or something causing bearings to overheat.

What are the brand and model of your septic pump? We can take a look at its specifications, duty cycle, and perhaps even check with the manufacturer. After all there are plenty of motors that work hard for many hours daily for many years.

DF

On 2018-07-04 by Peter E

Excellent webpage! Keep up the good work.
I have a 1 Hp motor in a septic system that keeps blowing run caps. They only last about a year each time. It has a pretty hard life and runs for around 6 hours every day. Is it permissible to replace the 12uF cap with a 15uF, 440V?

On 2018-07-11 by (mod) - how to read the numbers marked on a start or run capacitor

Robert

On the round capacitor I think I see 35+5 uF 440V - that'd be the cap rating.

The 5 is probably meant to read 5% - the accuracy or tolerance of the device around 30uf = or 30 microfarads.

Of course you'll need to match the terminals to get the right cap type. This is a starting capacitor from - what? Tell me the equipment.

[Click to enlarge any image]

On the oval capacitor shown below, I see 7.5uF +/1 5% and is nicely marked as "run capacitor".

Let me know if questions remain.

About buying replacements, try first your local electrical supplier; but these parts are sold universally online too by many vendors.

Sorry, we cannot provide these capacitors ourselves. InspectAPedia.com provides researched building and environmental diagnostic and repair information free to the public.

In order to absolutely assure our readers that we write and report without bias we do not sell any products nor do we have any business or financial relationships that could create such conflicts of interest.

On 2018-07-10 by Robert

Looking to replace my capacitors but still cant seem to figure it out. Can you provide me help or links to replace these capacitors.

Here is my other capacitor

Reader Question: distributor says the order of numbers on the capacitor doesn't matter

6/16/2014 Danno said:

I'm replacing the capacitor in my AC condenser. The original/stock unit says 35/5 440 AC. This is the cap I ordered from a distributor, but upon receiving it, the box says "5/35 440" (the 5 and 35 are transposed. Distributor says its the same thing. Is this correct? Thanks for any 411

Reply:

Danno I think the scrambled order is not an issue as long as the key numbers on the capacitor match its application or match the old one AND as long as you connect the proper wires.

Example start/run capacitor markings

(NOT specifying your particular capacitor)

• Voltage, e.g. 110-125V
• Capacitance, e.g. 189-227 µF or micro Farads or MFD (Start capacitors usually are over 60 µF)
• Capacitance, e.g. for a dual run capacitor: 35/5 refers to 35 MFD (for a compressor) and 5 MFD (for a fan motor)
• Temperature range, e.g. -40 - + 65C
• Cycles, e.g. 50-60 Hz

Decode a 35/5/440 marking on a motor starting capacitor

Reader Mark (18 June 2014) has given us a helpful and detailed translation of the markings found on start capacitors, repeated here:

Run capacitors: I always was taught that 35/5 was a [dual] run capacitor. 35 is the microfarad rating for the compressor & 5 microfarad was for the fan. (three terminals) not:

Decode a 35/5/440 marking on a motor starting capacitor:

The capacitor you are describing marked 35/5 440 is probably a dual run capacitor.

35/5 : The first two numbers are the capacitance 35 µF (for the compressor) and 5 µF (for the fan motor).

A dual "run capacitor" supports two electric motors, such as in large air conditioner or heat pump units, with both a fan motor and a compressor motor.

It saves space by combining two physical capacitors into one case. The dual capacitor has 3 terminals labeled

"C",

"FAN", and

"HERM", which stand for the Common, Fan, and HERMetically sealed compressor.[5]

440 refers to the ability to run voltages up to 440VAC

Dual run capacitors come in a variety of sizes, depending on the capacitance (µF), such as 40 plus 5 µF, and also the voltage. (Be sure to connect properly to compressor motor, fan motor and common)

A 440 volt capacitor can be used in place of a 370 volt, but not a 370 in place of a 440 volt.[2]

The capacitance must stay the same within 5% of its original value.[2]

Round cylinder-shaped dual run capacitors are commonly used for air conditioning, to help in the starting of the compressor and the condenser fan motor.[2]

An oval dual run capacitor could be used instead of a round capacitor, but the mounting strap should be changed to better fit the oval shape

Watch out: Take a look at the wiring sheet that should be with your capacitor or wiring marked on the device itself to be sure that you are properly connecting the Start and Run wires and you'll be OK.

As we noted in the article above, the dual capacitor terminals may be labeled so that the three leads can be wired correctly:

• S = start wire connector
• R = Run wire connector
• C = common connector

Reader Question: your capacitor advice is all Greek to me

I have a Wayne 1 HP motor used as a utility pump. The capacitor burnt out. It is a rectangle plastic capacitor with two wires coming off of it.

The numbers on it are: 30 F /J/250VAC I don’t see a U before the F there are two symbols that look like arrows pointing to the right before the F letter. There is a name on it that says YUHCHANG ( P )

I read you article on how to choose a capacitor still it’s all Greek to me. So what am I looking for?

Thanks for your time, - Anonymous by private email 2016/06/19

Reply: How to Choose the Correct Capacitor: four options

Anon: in response to your query I've re-written our capacitor selection explanation.

Four ways to find a matching or replacement motor capacitor are given at CAPACITOR SELECTION TIPS in this article.

Also if you can, send me some sharp photos of the cap and its markings and I may be able to comment further. Post a photo of your existing motor capacitor and its markings at the page bottom comments box, or use the page top or bottom CONTACT link.

Reader follow-up:

Here is a photo of the capacitor I'm talking about.

OK so we know this is probably just a single-purpose motor-start capacitor, since starting capacitors are most-often 125, 165, 250 and 330 volt devices while run capacitors are rated for higher levels like 370 and 440 volts. If it were a dual-purpose capacitor you'd see 3 rather than just 2 terminals.

You'll have no trouble buying a replacement at your local electrical supplier or even from an online supplier. Prices for a motor capacitor start at under $10. U.S.

Ask for a 30 microfarad 250VAC motor start capacitor. Take along the old sick one to show your supplier.

At MOTOR CAPACITOR WIRING GUIDE we show how to hook up a typical capacitor.

Watch out: Keep me posted on how you do, and work with POWER OFF so you live to tell me.

Question: what is the right start capacitor for the motor shown in this photo?

Could you please point me towards the correct capacitance for a start capacitor that can be connected to the engine presented in the attached picture?

I'm afraid I will install a too high or too low capacitance or voltage capacitor and damage the motor. T.P. by private email 2017/07/14

Reply:

The label reads 16 µF 450V, that's the capacitor that Zhang Qiu Hai Er DianJi You Xian Gong Si the manufacturer specifies for this particular electric motor, apparently model QC.J 01.

Reader follow-up:

Correct, the labels reads 16µF 450V. Is this the capacitance/voltage that I should use for the start capacitor? The 16µF seemed too low compared to the tables you presented in your website.

Reply:

The final Authority on the correct start or run capacitor to use with any motor is of course always the motors manufacturer.

The motor shown looks like a Haier double speed electric motor shown in the photo below, excerpted from haiermotor.en.ec21.com/ where no details nor specification sheets for the motor were found.

Zhangqiu Haier Electromotor Co., Ltd. is a long-established producer of Haier electric motors located in Zhangqiu Economic Development Zone Jinan, Shandong, China and doing business since 1958.

The company became a subsidiary of Haier Group in 1998. These motors are used in household appliances such as washing machines, with other motor models used in refrigerators, air conditioners and other equipment.

More information including contact suggestions for repair parts or service are found at HAIER & HAIER AMERICA

...

Continue reading  at CAPACITOR SIZE DETERMINATION for ELECTRIC MOTORS - topic home, or select a topic from the closely-related articles below, or see the complete ARTICLE INDEX.

Or see these

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• BASIC ELECTRICAL TESTS for BURNED OUT COMPRESSOR MOTORS
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• ELECTRIC MOTOR CENTRIFUGAL SWITCH or PTC PRD
• ELECTRIC MOTOR DIAGNOSTIC GUIDE
• HARD STARTING ELECTRIC MOTOR CAUSES

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CHOOSE a START RUN CAPACITOR FAQs-2 at InspectApedia.com - online encyclopedia of building & environmental inspection, testing, diagnosis, repair, & problem prevention advice.

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