Antique Engines and Old Iron
[Home] - [HELP] - [Forums] - [Groups] - [Classified Ads] - [Subscribe] - [Books] - [Sponsors] -

Go Back   SmokStak > SmokStak® Vintage Electrical Equipment > Amateur "HAM" Radio
Forgot Password? Join Us!

Notices

Amateur "HAM" Radio Radio Amateurs, Morse Code, Transmitter Tubes, Vintage Equipment, Antennas

Amateur

Capacitor Testing


this thread has 25 replies and has been viewed 736 times

Reply
 
Thread Tools Display Modes
  #1  
Old 08-06-2019, 06:39:39 PM
dalmatiangirl61 dalmatiangirl61 is offline
Subscriber
 
Join Date: Feb 2010
Location: San Marcos, Texas / McGill, Nevada
Posts: 4,851
Thanks: 5,794
Thanked 4,153 Times in 2,052 Posts
Default Capacitor Testing

Not quite HAM related, but not sure where else to put this, and you guys probably know this subject best. I need advice on testing capacitors, not the little tiny ones on circuit boards, but can types and motor run/start type. Youtube gave me some info on how to test with basic multimeter, I have 2 identical caps and getting different readings, yet not sure which one is bad. I can get a better meter with capacitance testing, that will help. Going further down the rabbit hole of capacitor testing videos I learned that the multimeter cap testing is not 100% definitive as it does not measure cap leakage. Using a Heathkit IT-11 capacitor tester would let me detect leakage, but not sure what the max uf rating is on that machine. If a tester has a max rating of 60uf, is there a way to test a 600uf capacitor with it? Heathkit IT-11's run about $300ish on ebay, any suggestions on better units to watch for? I'm tired of guessing if caps are bad.
__________________
Those who can see the invisible, can do the impossible
Reply With Quote
Sponsored Links
  #2  
Old 08-06-2019, 07:02:08 PM
Vanman Vanman is offline
Subscriber
 
Join Date: Aug 2011
Location: Mission Viejo, California
Posts: 6,017
Thanks: 9,928
Thanked 2,842 Times in 1,911 Posts
Default Re: Capacitor Testing

For these types of caps I test them with 120 volts, 60 cycles, and an ammeter. Trying to remember the formula that relates capacitance to impedance...

1/2πfc?

Yes, that equals impedance, Xc. Divide applied voltage by measured current to determine impedance. F is 60, π is ~3.14, solve for C.

When testing electrolytic capacitors (start caps), do not leave them in the circuit for more than a few seconds! Otherwise they'll make a mess of your shop AND your shorts!!

Keith
Reply With Quote
The Following User Says Thank You to Vanman For This Post:
  #3  
Old 08-06-2019, 07:30:26 PM
Radiomike Radiomike is offline
Registered-II
 
Join Date: Feb 2013
Location: Pincher Creek, Alberta, Canada
Posts: 505
Thanks: 0
Thanked 246 Times in 173 Posts
Default Re: Capacitor Testing

Testing with an ammeter and 120Volts / 60Hz is an excellent way to go. I do the same but put a 100W bulb in series so the current is limted to an amp or so. Ammeters are expensive! Measure the capacitor volts and the current, this gives impedance There are online calculators to work out things as well https://www.allaboutcircuits.com/too...ce-calculator/

If you are really keen then the three voltmeter method will allow you to calculate tanδ. You need a resistor about the same impedance as the capacitor. Connect in series with the capacitor and with a FUSE to the mains at 60Hz. even better if you have and isolation transformer. Measure all three voltages, mains, capacitor and resistor. Then either graphically of using the cosine rule you can find the impedance of the capacitor and its loss angle. The assumption is the resistor is non inductive.

Another way, from an old radio book, is to apply 2.65Volts 60Hz and the capacitance is 1mA = 1µf this needs a variac and an transformer. So you would get 600mA

I usually use my insulation tester for leakage and then an ammeter / voltmeter to get the capacitance. Be cautious when doing start capacitors as they are short time rated only.

A 600µf capacitor has an impedance of only 4 or 5 Ω so a big light bulb in series will be essential, try with a 100W and then a 300W. The ammeter method will still work take the voltage across the capacitor and the circuit amps. This value must be a start capacitor. the time rating will be marked on it, usually less than a minute. Be aware as well that it will retain a charge and can do you some serious damage.

Mike
Reply With Quote
The Following User Says Thank You to Radiomike For This Post:
  #4  
Old 08-06-2019, 08:01:04 PM
dalmatiangirl61 dalmatiangirl61 is offline
Subscriber
 
Join Date: Feb 2010
Location: San Marcos, Texas / McGill, Nevada
Posts: 4,851
Thanks: 5,794
Thanked 4,153 Times in 2,052 Posts
Default Re: Capacitor Testing

So what you are saying is there is no tester to plug a cap into and get a good/bad reading? I'm still trying to process what you two wrote,,,,,what is Tano?

Drove into town to find a better meter, no luck but they did have nice selection of analog multimeters.... I need a recommendation for a good mid grade multimeter with capacitance and diode testing from Amazon or ebay.
__________________
Those who can see the invisible, can do the impossible
Reply With Quote
  #5  
Old 08-06-2019, 10:15:45 PM
OnanParts's Avatar
OnanParts OnanParts is offline
Sponsor
 
Join Date: Nov 2008
Location: Pacific Northwest, USA
Posts: 1,074
Thanks: 105
Thanked 1,487 Times in 597 Posts
Default Re: Capacitor Testing

Quote:
Originally Posted by dalmatiangirl61 View Post
So what you are saying is there is no tester to plug a cap into and get a good/bad reading? I'm still trying to process what you two wrote,,,,,what is Tano?

Drove into town to find a better meter, no luck but they did have nice selection of analog multimeters.... I need a recommendation for a good mid grade multimeter with capacitance and diode testing from Amazon or ebay.
This one is on my list...

https://www.amazon.com/Peak-Electron...N7M0N1SPSE6VZA

Their website:
https://www.peakelec.co.uk/acatalog/...esr-meter.html
__________________
https://www.onanparts.com
Reply With Quote
The Following User Says Thank You to OnanParts For This Post:
  #6  
Old 08-06-2019, 10:52:47 PM
ulgydog56's Avatar
ulgydog56 ulgydog56 is offline
Registered-II
 
Join Date: Dec 2017
Location: Smithcreek, Michigan
Posts: 612
Thanks: 73
Thanked 273 Times in 205 Posts
Default Re: Capacitor Testing

go to any heating & cooling supply house for a supco cap tester, not that much money, made for cap testing only, gives mf reading or tells you if its open, use one for the last 20 years, never let me down, tested 1000s of caps...

Last edited by ulgydog56; 08-06-2019 at 11:02:06 PM. Reason: added
Reply With Quote
The Following User Says Thank You to ulgydog56 For This Post:
  #7  
Old 08-06-2019, 11:51:59 PM
dalmatiangirl61 dalmatiangirl61 is offline
Subscriber
 
Join Date: Feb 2010
Location: San Marcos, Texas / McGill, Nevada
Posts: 4,851
Thanks: 5,794
Thanked 4,153 Times in 2,052 Posts
Default Re: Capacitor Testing

That Supco tester looks like it will fill my needs well, thank you! Curious, not that its likely to happen too often, lets say I need to measure 1.5F (farad, not micro farad), is there a way to divide the readings? Same as 60uf/600uf question above.

Hmm, the ESR70 has a broader range than the Supco, decisions decisions.....
__________________
Those who can see the invisible, can do the impossible
Reply With Quote
  #8  
Old 08-07-2019, 09:26:28 AM
Radiomike Radiomike is offline
Registered-II
 
Join Date: Feb 2013
Location: Pincher Creek, Alberta, Canada
Posts: 505
Thanks: 0
Thanked 246 Times in 173 Posts
Default Re: Capacitor Testing

There are many capacitor testers on the market and if you are doing lots they are a good investment. I do possibly three or four a year and do leakage and current to calculate the value.

tanδ (greek lower case delta) is a measurement you can derive from the three voltmeter method (or from bridge methods) which with some manipulation gives a value for the equivalent series resistance ESR this is the simplest explanation I could find https://en.wikipedia.org/wiki/Dissipation_factor and

https://www.illinoiscapacitor.com/pd...factor_ESR.pdf

600µf is a large capacitor for motors, or is it an electronic component. Only some capacitors are rated for AC, like motor start and run capacitors. Many standard electronic aluminium electrolytics are only rated for use with DC.

Mike
Reply With Quote
The Following 2 Users Say Thank You to Radiomike For This Post:
  #9  
Old 08-07-2019, 02:26:34 PM
dalmatiangirl61 dalmatiangirl61 is offline
Subscriber
 
Join Date: Feb 2010
Location: San Marcos, Texas / McGill, Nevada
Posts: 4,851
Thanks: 5,794
Thanked 4,153 Times in 2,052 Posts
Default Re: Capacitor Testing

Most of what I see is caps for industrial electrical stuff, current list of caps with question marks on them is the 53000uf 30vdc cap in Hobart welder, then the 4000uf 100vdc caps I pulled from Miller welder, and the used 2200uf 100vdc caps I put into Miller welder. I need a definitive way to test these types of caps, I have no way of knowing if the ones I'm pulling are truly bad, or if the used caps I'm replacing them with are truly good.

Neither the ESR 70 (20,000uf max) or Supco (9,999uf max) tester will work with the 53000uf cap, certainly there is some type of tester or procedure for testing these.

Answer might be in posts #2&3, but you need to dumb it down a little for me to understand
__________________
Those who can see the invisible, can do the impossible
Reply With Quote
  #10  
Old 08-07-2019, 04:45:01 PM
Jasen Jasen is offline
Registered
 
Join Date: Jun 2018
Location: Addison, Michigan, USA
Posts: 4
Thanks: 0
Thanked 6 Times in 2 Posts
Default Re: Capacitor Testing

I have ordered several things from this company. Haven't tried this yet but I plan on getting one.

https://www.mpja.com/Digital-Inducta...tinfo/33374+TE

You will need to build your own enclosure though.
Reply With Quote
The Following User Says Thank You to Jasen For This Post:
  #11  
Old 08-07-2019, 05:12:45 PM
dalmatiangirl61 dalmatiangirl61 is offline
Subscriber
 
Join Date: Feb 2010
Location: San Marcos, Texas / McGill, Nevada
Posts: 4,851
Thanks: 5,794
Thanked 4,153 Times in 2,052 Posts
Default Re: Capacitor Testing

Jason
Looking at specs of that unit it has a max capacity of 100uf, well short of the 53000uf capacitor I need to test. Are there testers for these higher value caps? Or is there a way to divide/multiply signal for testing caps above 100uf.

If looking at multimeters with cap testing capabilities, are there models that will test 53000uf that anyone can recommend?

Looking at Klein MM700 multimeter shows it has a max capacitance reading of 4000uf, still a far cry from the 53000uf I need to test.
__________________
Those who can see the invisible, can do the impossible

Last edited by dalmatiangirl61; 08-07-2019 at 06:15:31 PM.
Reply With Quote
  #12  
Old 08-07-2019, 07:01:19 PM
Radiomike Radiomike is offline
Registered-II
 
Join Date: Feb 2013
Location: Pincher Creek, Alberta, Canada
Posts: 505
Thanks: 0
Thanked 246 Times in 173 Posts
Default Re: Capacitor Testing

A 50000µF capacitor has an impedance of 0.05Ω at 60Hz. A very low figure to try and measure. some mothhodes to mull over.

1. Charge to a known voltage and discharge through a resistor from this you get the time constant and hence the capacitance. There are on line calculators to do this manipulation of the figures, You need a stop watch and a good voltmeter. Usually three shots will be sufficient.

2.

---------- Post added at 05:01:19 PM ---------- Previous post was at 04:51:08 PM ----------

2. Apply known AC volts measure the current, 2.65Volts is 1mA per 1µf. Although 50000µf. will be 50Amps, 0.265Volts will be 5amps or so. You could put lots in series and wind up the volts until you get say 5 or 10 Amps, measure voltages across each capacitor and the current. Calculate Z from this and knowing ω you can get C.

3. Put a known good capacitor in series with the suspect unit to bring the capacitance within range of the meter. 2 x 50000µf. in series gives 25000µf. This will not be as precise, but may enable you to proceed. This depends on having a known good capacitor.

Mike
Reply With Quote
  #13  
Old 08-08-2019, 12:16:02 AM
Power Power is offline
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 5,361
Thanks: 1,235
Thanked 3,215 Times in 1,894 Posts
Default Re: Capacitor Testing

Quote:
Originally Posted by Radiomike View Post
3. Put a known good capacitor in series with the suspect unit to bring the capacitance within range of the meter. 2 x 50000µf. in series gives 25000µf.
Mike
HMM- almost, but no.

Series and Parallel Capacitors
Chapter 13 - Capacitors

When capacitors are connected in series, the total capacitance is less than any one of the series capacitors’ individual capacitances. If two or more capacitors are connected in series, the overall effect is that of a single (equivalent) capacitor having the sum total of the plate spacings of the individual capacitors. As we’ve just seen, an increase in plate spacing, with all other factors unchanged, results in decreased capacitance.

capacitors connected in series

Thus, the total capacitance is less than any one of the individual capacitors’ capacitances. The formula for calculating the series total capacitance is the same form as for calculating parallel resistances:
Reply With Quote
  #14  
Old 08-08-2019, 08:32:18 AM
Jasen Jasen is offline
Registered
 
Join Date: Jun 2018
Location: Addison, Michigan, USA
Posts: 4
Thanks: 0
Thanked 6 Times in 2 Posts
Default Re: Capacitor Testing

I thought specs showed up to 100mf which = 100,000uf I thought? Sorry if I was incorrect.

Capacitance: 0.01pF -10uF
Resolution:0.01pF
Hi Cap: 1uF-100mF
Resolution: 0.01uF
Accuracy: 0.01pF-1pF: 5%
1pF-1uF: 1%
1uF-10uF: 5%
Hi Cap: 1uF-100mF: 5%
Inductance: 0.001uH -100mH
Resolution:0.001uH

And this is a clip from a review: " I also checked the high capacitance range - four 22,000uF 16V capacitors in parallel measured 92mF after an 8 second pause - dead-on."
Reply With Quote
  #15  
Old 08-08-2019, 09:46:01 AM
Radiomike Radiomike is offline
Registered-II
 
Join Date: Feb 2013
Location: Pincher Creek, Alberta, Canada
Posts: 505
Thanks: 0
Thanked 246 Times in 173 Posts
Default Re: Capacitor Testing

The capacitor value I used was 50,000µf, two identical value units in series applying the formulae of reciprocal values gives 25,000µf. Which is ˝ of the value of the individual capacitor.

Mike
Reply With Quote
  #16  
Old 08-08-2019, 01:07:13 PM
dalmatiangirl61 dalmatiangirl61 is offline
Subscriber
 
Join Date: Feb 2010
Location: San Marcos, Texas / McGill, Nevada
Posts: 4,851
Thanks: 5,794
Thanked 4,153 Times in 2,052 Posts
Default Re: Capacitor Testing

I thought 100uf = 100mfd = 100mf, ie all express 100 micro farads, maybe I'm wrong?

Sent some questions off to Supco yesterday, they informed me that the Mfd110 tester only works on AC capacitors, I have 10 capacitors sitting in front of me right now, they all are labeled in VDC.

What am I not getting here? What question am I not asking properly? This type of cap is in 90+% of the equipment I work on, pretty sure some of these style caps were used in sending men to the moon, and probably thousands in use maintaining people in space today, and our best test procedure is a volt meter and a stopwatch


Pulled 35000uf cap yesterday, its showing a dead short between terminals so I guess it is officially dead, sure would be nice to be able to test the replacement cap before installation to know it is not half dead

Edit: Oh yeah, in watching capacitor testing videos I learned capacitor leakage test is testing for dc leakage in AC caps. So do dc caps leak? If so do they leak ac or dc?????
__________________
Those who can see the invisible, can do the impossible
Reply With Quote
  #17  
Old 08-08-2019, 01:27:12 PM
Power Power is offline
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 5,361
Thanks: 1,235
Thanked 3,215 Times in 1,894 Posts
Default Re: Capacitor Testing

Quote:
Originally Posted by dalmatiangirl61 View Post
I I learned capacitor leakage test is testing for dc leakage in AC caps. So do dc caps leak? If so do they leak ac or dc?????
If you find one that leaks AC, then I want to go into partnership with you. We will soon be extremely wealthy.
Reply With Quote
The Following User Says Thank You to Power For This Post:
  #18  
Old 08-08-2019, 07:46:48 PM
Pete Deets Pete Deets is offline
Registered-III
 
Join Date: Feb 2006
Location: Evansville, WI. USA
Posts: 1,517
Thanks: 820
Thanked 1,579 Times in 688 Posts
Default Re: Capacitor Testing

Quote:
Originally Posted by dalmatiangirl61 View Post
,,,Pulled 35000uf cap yesterday, its showing a dead short between terminals so I guess it is officially dead, sure would be nice to be able to test the replacement cap before installation to know it is not half dead...
d-girl,
Please forgive the dumb question but how long did you have your tester connected or did it stay a dead short? The larger caps take a while to charge up enough to show some resistance..........PD
Reply With Quote
The Following User Says Thank You to Pete Deets For This Post:
  #19  
Old 08-08-2019, 08:32:36 PM
dalmatiangirl61 dalmatiangirl61 is offline
Subscriber
 
Join Date: Feb 2010
Location: San Marcos, Texas / McGill, Nevada
Posts: 4,851
Thanks: 5,794
Thanked 4,153 Times in 2,052 Posts
Default Re: Capacitor Testing

Quote:
Originally Posted by Pete Deets View Post
d-girl,
Please forgive the dumb question but how long did you have your tester connected or did it stay a dead short? The larger caps take a while to charge up enough to show some resistance..........PD
I tested several times, maybe had leads connected 30 seconds cumulatively. All other caps would start at a low value, then slowly climb to 199, then infinity? Same reading as leads not connected to anything. The 35000uf cap was going to 00.0 as if leads were shorted.

Pulled out power supply today, applied 20v to the 35000uf cap for maybe 30 seconds, tested with volt meter and it showed 12 volts, left meter connected for 20 minutes, it still showed 8 volts. Discharged by shorty, visible spark, now when I test cap with ohm meter it starts at a low value and starts climbing. I don't get it, it showed dead yesterday, now it looks maybe ok

Doing some reading, trying real hard to understand these things. One of the things I read said there is no such thing as dc capacitors, just un-polarized and polarized, so I'm trying to understand why some caps are labeled VAC, and others vdc?

I've watched enough videos now that if you handed me an ESR70 and Sprague TO-6 Tel-Ohmike Capacitor Analyzer I could tell you uf rating, esr, and leakage of an AC capacitor, but I have no idea if any of those procedures cross over to a cap with vdc stamped into label because none of those vids show that

Edit. If the Supco tester only works on AC caps, why is one lead red and other black????
__________________
Those who can see the invisible, can do the impossible
Reply With Quote
  #20  
Old 08-08-2019, 09:25:39 PM
Power Power is offline
Registered-III
 
Join Date: Aug 2011
Location: New Jersey
Posts: 5,361
Thanks: 1,235
Thanked 3,215 Times in 1,894 Posts
Default Re: Capacitor Testing

[QUOTE=dalmatiangirl61;1595477]I tested several times, maybe had leads connected 30 seconds cumulatively. All other caps would start at a low value, then slowly climb to 199, then infinity? Same reading as leads not connected to anything. The 35000uf cap was going to 00.0 as if leads were shorted. I have had that happen with caps that were sitting for years. Once powered up,, worked fine.

Pulled out power supply today, applied 20v to the 35000uf cap for maybe 30 seconds, tested with volt meter and it showed 12 volts, left meter connected for 20 minutes, it still showed 8 volts. Discharged by shorty, visible spark, now when I test cap with ohm meter it starts at a low value and starts climbing. I don't get it, it showed dead yesterday, now it looks maybe ok

Doing some reading, trying real hard to understand these things. One of the things I read said there is no such thing as dc capacitors, just un-polarized and polarized, so I'm trying to understand why some caps are labeled VAC, and others vdc? Well, a polarized capacitor on AC soon becomes a firecracker. Polarized is designed to rise to circuit DC voltage and stay there. AC capacitor has to charge, discharge and reverse charge at whatever frequency system runs at. LOTS more stress.

I've watched enough videos now that if you handed me an ESR70 and Sprague TO-6 Tel-Ohmike Capacitor Analyzer I could tell you uf rating, esr, and leakage of an AC capacitor, but I have no idea if any of those procedures cross over to a cap with vdc stamped into label because none of those vids show that

Edit. If the Supco tester only works on AC caps, why is one lead red and other black????
Reply With Quote
The Following User Says Thank You to Power For This Post:
Reply

Bookmarks


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

F o r u m Jump

Similar Threads Chosen at Random
Thread Thread Starter F o r u m Replies Last Post
2.0 P.E capacitor Kevin New Mexico Onan Generators 5 03-24-2015 11:34:48 PM
need a new capacitor on an old Colman 54 markH Generators & Electric Motors General Discussion 3 12-14-2012 02:25:36 PM
25mfd capacitor PRoot Generac Generators (SEARS, etc.) 8 02-10-2012 08:48:25 PM
Which capacitor for my K-W flasks Magnetos, Ignition Coils and Spark Plugs 7 08-21-2008 10:26:38 AM
.1 mfd Capacitor Tom Jamboretz Onan Generators 5 04-24-2005 12:31:09 AM


Use "Ctrl" mouse wheel to change screen size.
All times are GMT -4. The time now is 09:35:01 PM.

Smokstak and Enginads site search!


All use is subject to our TERMS OF SERVICE
SMOKSTAK® is a Registered Trade Mark - A Community of Antique Engine Enthusiasts
Copyright © 2000 - 2019 by Harry Matthews P.O. Box 5612 - Sarasota, FL 34277