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sharpi31 9th June 2012 12:42 PM

ESR measurements of various caps
 
I bought a cheap LCM3 ESR meter on eBay and thought I'd measure some of the many caps I have acquired over the years. Measurement frequency was 91.5KHz.

The meter was calibrated and caps discharged before each measurement. Meausured capacitance and ESR are given for each.

Rubycon ZLH 1800uF/16V - 2360uf/18mohm
K42-19 12uF/500V - 11.6uF/15mohm
Ampohm PF-XAL-AL 4.7uF/630V - 4.46uF/58mohm
K75-10 1.5uF/500uF - 1.5uF/68mohm
Random 68000uF/16V - 83100uF/47mohm
CDJ MKP (?) 200uF/450V - 193uF/269mohm
Jupiter beeswax 3.3uF/600V - 4.41uF/16mohm
Epcos Sikorel B41570 2200uF/100V - 2260uF/47mohm
Nover LA 10000uF/63V - 9560uF/49mohm
BHC Aerovox ALC40 680uF/200V - 613uF/99mohm
Epcos Sikorel B41590 470uF/63V - 538uF/54mohm
Epcos Sikorel B41684 470uF/35V - 483uF/43mohm
Siemens MKV B25834 10uF/630V - 9.88uF/37mohm
ASC GLY513 600uF/500V - 603 uF/6mohm
Ronken oil motor run 25uF/530uF - 25.6uF/208mohm
Jensen Alu foil paper oil 20uF/100V - 19.8uF/15mohm
NCC solid polymer 470uF/16V - 483uF/9mohm

The caps are all different ages, and I didn't standardise temperature (although all were in my garage at approx 14degrees C for weeks) so the measurements aren't really comparable in any useful way.

Having said that I was very impressed with the ASC GLY513 and very disappointed with the cheap eBay CDJ MKP 200uF caps, which I strongly suspect are electrolytics rather than MKP as advertised.

davidsrsb 9th June 2012 02:19 PM

MKP motor capacitors have to be self healing, which means VERY thin metal deposit and hence rather high series resistance. Capcitors with foil layers have much lower ESR

crispycircuit 9th June 2012 05:29 PM

I always wondered....
 
Very interesting! You would think price equals low ESR, but not really. I'd like to know more and how it relates to amplifiers....

davidsrsb 10th June 2012 08:55 AM

Just that motor run capacitors have different priorities and are not intended for filtering/decoupling

ticktock 30th May 2013 01:26 AM

Quote:

Originally Posted by sharpi31 (Post 3053303)
I bought a cheap LCM3 ESR meter on eBay and thought I'd measure some of the many caps I have acquired over the years. Measurement frequency was 91.5KHz.

The meter was calibrated and caps discharged before each measurement. Meausured capacitance and ESR are given for each.

Rubycon ZLH 1800uF/16V - 2360uf/18mohm
K42-19 12uF/500V - 11.6uF/15mohm
Ampohm PF-XAL-AL 4.7uF/630V - 4.46uF/58mohm
K75-10 1.5uF/500uF - 1.5uF/68mohm
Random 68000uF/16V - 83100uF/47mohm
CDJ MKP (?) 200uF/450V - 193uF/269mohm
Jupiter beeswax 3.3uF/600V - 4.41uF/16mohm
Epcos Sikorel B41570 2200uF/100V - 2260uF/47mohm
Nover LA 10000uF/63V - 9560uF/49mohm
BHC Aerovox ALC40 680uF/200V - 613uF/99mohm
Epcos Sikorel B41590 470uF/63V - 538uF/54mohm
Epcos Sikorel B41684 470uF/35V - 483uF/43mohm
Siemens MKV B25834 10uF/630V - 9.88uF/37mohm
ASC GLY513 600uF/500V - 603 uF/6mohm
Ronken oil motor run 25uF/530uF - 25.6uF/208mohm
Jensen Alu foil paper oil 20uF/100V - 19.8uF/15mohm
NCC solid polymer 470uF/16V - 483uF/9mohm

The caps are all different ages, and I didn't standardise temperature (although all were in my garage at approx 14degrees C for weeks) so the measurements aren't really comparable in any useful way.

Having said that I was very impressed with the ASC GLY513 and very disappointed with the cheap eBay CDJ MKP 200uF caps, which I strongly suspect are electrolytics rather than MKP as advertised.


Thank you !!! :cheers:

AJT 8th June 2013 02:31 AM

Quote:

CDJ MKP (?) 200uF/450V - 193uF/269mohm
what is wrong here anyway?

sharpi31 8th June 2013 05:19 AM

The cdj mkp(?) 450v 200uf caps are available on eBay and cost significantly less than other equivalent film caps.

CDJ MKP Polypropylene Film Motor Start-up Capacitor 450VAC 200uF 10% | eBay

Perhaps naively I expected lower ESR from an MKP cap, so suspected that they might be electrolytic in disguise, however it would make sense that very thin metal deposits would make the ESR high. I'm tempted to cut one open to confirm.

There is no real problem if the cap is real MKP and just high ESR, as they would still be useful in tube amp CRC supplies etc.

Elvee 8th June 2013 06:57 AM

Quote:

Originally Posted by sharpi31 (Post 3519142)

Perhaps naively I expected lower ESR from an MKP cap, so suspected that they might be electrolytic in disguise, however it would make sense that very thin metal deposits would make the ESR high. I'm tempted to cut one open to confirm.

There is no real problem if the cap is real MKP and just high ESR, as they would still be useful in tube amp CRC supplies etc.

Does your instrument measure the actual esr (ie the resistive component of the impedance), or just the modulus of the impedance?
This could explain the high reading, because in caps intended for low frequency operation, no effort is made to minimize the series inductance

sharpi31 8th June 2013 07:49 AM

I don't know the answer to your question, sorry. This site may confirm one way or the other, if you know what you're looking for....

Google Translate

Elvee 8th June 2013 10:29 AM

It isn't very clear, and the Google translation tends to make things even less clear with this kind of phrase:

Quote:

The woman in charge is directly proportional to the charging current (I).
There is a way to detect it though: measure a capacitor in series with a ~20cm piece of straight wire, and then coil the wire around an insulating cylinder like a pen (or a ferrite stick). This will not change the resistance, but it will increase the modulus of the impedance. If the reading changes, this means that the instrument is scalar, not vectorial.


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