tabbypurr@gmail.com wrote...> Winfield Hill wrote: >> tabbypurr wrote... >>> >>> Leakage is a normal part of electrolytic operation. >> >> I understand the normal leakage. But excess leakage one >> sees after over anodization, etc., high leakage that only >> gets worse with time, that's got to be part of a failure >> process. Once the formed oxide layer has been thoroughly >> penetrated, new processes can take place ... > > Leakage current going high & the cap reforming at power-on > is not always failure or imminent failure.Yes, right. Classic old-capacitor reforming is done with a forgiving environment, like a 1k series resistor, etc. What about an instrument that's powered up after having been off for a decade or two? What about excessive currents, are they really only forming currents? I purchased a really useful instrument, a HANEG** HM2814A, for electrolytic capacitor leakage tests. The instrument works to 500V, has multiple test settings, current limits, meter readouts and diagnostics. My designs use lots of 450V electrolytic capacitors, some in series, and I often check them on this instrument. I've encountered new-stock but maybe older* 450V caps, designed for use at 380V, but with massive excess leakage at only 350 volts. From the increasing current levels, I'm convinced that these parts would fail, if forced to operate at their design voltage (note: 18% safety margin). I didn't test to destruction. From what I've seen, none of the manufacturer's lengthy design notes deal with this failure mode. I've had lots of experience with carbon pathways that behave this way. The leakage currents continue to increase without limit. * Lots of my new inventory is 15 to 20 years old, arrgh! ** The name is HANEG, but its HM part number implies HAMEG, so I placed its info in my HAMEG folder. A made-in-China thingie, Google doesn't have much info about HM2814A, but gives a name Jinyitong Electronics. It came with a good manual, and very useful accessories, but no mention of a manufacturer's name. But it's a very useful instrument. -- Thanks, - Win
Film capacitor as power-supply filter
Started by ●October 7, 2019
Reply by ●October 9, 20192019-10-09
Reply by ●October 9, 20192019-10-09
On Wednesday, October 9, 2019 at 10:14:57 PM UTC-4, Winfield Hill wrote:> > I purchased a really useful instrument, a HANEG** HM2814A, > for electrolytic capacitor leakage tests. The instrument > works to 500V, has multiple test settings, current limits, > meter readouts and diagnostics. My designs use lots of > 450V electrolytic capacitors, some in series, and I often > check them on this instrument. I've encountered new-stock > but maybe older* 450V caps, designed for use at 380V, but > with massive excess leakage at only 350 volts. From the > increasing current levels, I'm convinced that these parts > would fail, if forced to operate at their design voltage > (note: 18% safety margin). I didn't test to destruction.Exactly why I'm fixing up this vintage Heathkit IT-11. It's great for re-forming and for testing leakage. I am going to calibrate the leakage tests so I know how many microamps is the pass/fail threshold for each of the three. And probably change them to whatever I think is useful with modern capacitors.
Reply by ●October 10, 20192019-10-10
On Thursday, 10 October 2019 03:14:57 UTC+1, Winfield Hill wrote:> tabbypurr wrote... > > Winfield Hill wrote: > >> tabbypurr wrote...> >>> Leakage is a normal part of electrolytic operation. > >> > >> I understand the normal leakage. But excess leakage one > >> sees after over anodization, etc., high leakage that only > >> gets worse with time, that's got to be part of a failure > >> process. Once the formed oxide layer has been thoroughly > >> penetrated, new processes can take place ... > > > > Leakage current going high & the cap reforming at power-on > > is not always failure or imminent failure. > > Yes, right. > > Classic old-capacitor reforming is done with a forgiving > environment, like a 1k series resistor, etc.Yes, and sometimes the unit itself provides that. And sometimes it doesn't but C survives & reforms.> What about > an instrument that's powered up after having been off for > a decade or two?'what about' is always a too-vague question> What about excessive currents, are they > really only forming currents?Excessive currents are by definition excessive, though nothing is said there about the definition that makes it so. Some caps reform, some don't. A variac or limited current dc psu is useful. The need for a reform does not always mean a cap is faulty or nearing failure, sometimes it does. NT
Reply by ●October 10, 20192019-10-10
On Thursday, October 10, 2019 at 9:59:16 AM UTC+11, tabb...@gmail.com wrote:> On Wednesday, 9 October 2019 22:46:25 UTC+1, Phil Allison wrote: > > Some Criminal Nut case called tabby wrote: > > ---------------------------------------------------- > > > > > > > > Yes. Your point? > > > > > > ** Obvious to anyone who is not a trolling mental defective. > > > > FOAD > > It's obvious you had nothing to add.NT never has, and
Reply by ●October 10, 20192019-10-10
On 9 Oct 2019 19:14:47 -0700, Winfield Hill <winfieldhill@yahoo.com> wrote:>tabbypurr@gmail.com wrote... >> Winfield Hill wrote: >>> tabbypurr wrote... >>>> >>>> Leakage is a normal part of electrolytic operation. >>> >>> I understand the normal leakage. But excess leakage one >>> sees after over anodization, etc., high leakage that only >>> gets worse with time, that's got to be part of a failure >>> process. Once the formed oxide layer has been thoroughly >>> penetrated, new processes can take place ... >> >> Leakage current going high & the cap reforming at power-on >> is not always failure or imminent failure. > > Yes, right. > > Classic old-capacitor reforming is done with a forgiving > environment, like a 1k series resistor, etc. What about > an instrument that's powered up after having been off for > a decade or two? What about excessive currents, are they > really only forming currents? > > I purchased a really useful instrument, a HANEG** HM2814A, > for electrolytic capacitor leakage tests. The instrument > works to 500V, has multiple test settings, current limits, > meter readouts and diagnostics. My designs use lots of > 450V electrolytic capacitors, some in series, and I often > check them on this instrument. I've encountered new-stock > but maybe older* 450V caps, designed for use at 380V, but > with massive excess leakage at only 350 volts. From the > increasing current levels, I'm convinced that these parts > would fail, if forced to operate at their design voltage > (note: 18% safety margin). I didn't test to destruction. > > From what I've seen, none of the manufacturer's lengthy > design notes deal with this failure mode. I've had lots > of experience with carbon pathways that behave this way. > The leakage currents continue to increase without limit. > > * Lots of my new inventory is 15 to 20 years old, arrgh! > > ** The name is HANEG, but its HM part number implies HAMEG, > so I placed its info in my HAMEG folder. A made-in-China > thingie, Google doesn't have much info about HM2814A, but > gives a name Jinyitong Electronics. It came with a good > manual, and very useful accessories, but no mention of a > manufacturer's name. But it's a very useful instrument.I've heard of people using a variac to slowly bring up an old instrument. -- John Larkin Highland Technology, Inc lunatic fringe electronics
Reply by ●October 10, 20192019-10-10
jlarkin@highlandsniptechnology.com wrote...> > I've heard of people using a variac to > slowly bring up an old instrument.I should try that. -- Thanks, - Win
Reply by ●October 10, 20192019-10-10
On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, jla...@highlandsniptechnology.com wrote:> I've heard of people using a variac to slowly bring up an old > instrument.A switchmode regulated supply, though, takes maximum current input when voltage is low-to-borderline. So that mainly is good for unregulated power (or power-wasting series or shunt regulated). It's also questionable if there's a DC fan, or ferroresonant circuit...
Reply by ●October 10, 20192019-10-10
On Thu, 10 Oct 2019 16:36:35 -0700 (PDT), whit3rd <whit3rd@gmail.com> wrote:>On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, jla...@highlandsniptechnology.com wrote: > >> I've heard of people using a variac to slowly bring up an old >> instrument. > >A switchmode regulated supply, though, takes maximum current input >when voltage is low-to-borderline. So that mainly is good for >unregulated power (or power-wasting series or shunt regulated). >It's also questionable if there's a DC fan, or ferroresonant circuit...I meant an OLD instrument.
Reply by ●October 10, 20192019-10-10
On Thursday, October 10, 2019 at 7:40:27 PM UTC-4, John Larkin wrote:> On Thu, 10 Oct 2019 16:36:35 -0700 (PDT), whit3rd wrote: > > >On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, John Larkin wrote: > > > >> I've heard of people using a variac to slowly bring up an old > >> instrument. > > > >A switchmode regulated supply, though, takes maximum current input > >when voltage is low-to-borderline. So that mainly is good for > >unregulated power (or power-wasting series or shunt regulated). > >It's also questionable if there's a DC fan, or ferroresonant circuit... > > I meant an OLD instrument.Back in the '60 and '70s we would apply 12 to 24 volts to old equipment to warm the power transformer to drive out moisture. The tubes were pulled, first and it was left on this setup for 24 hours. It seemed like every old piece of test equipment was store in a dank basement. I had a Sprague TO6 capacitor analyzer that could reform to 500VDC, and it metered the leakage current. If the oxide layer was bad, you could slowly ramp it up until it had acceptable leakage at the rated voltage. The Military had a set schedule to test and reform NOS electrolytics that were in warehouses. I used to see a lot of surplus caps with a label showing the dates.
Reply by ●October 10, 20192019-10-10
On Thu, 10 Oct 2019 17:00:16 -0700 (PDT), Michael Terrell <terrell.michael.a@gmail.com> wrote:>On Thursday, October 10, 2019 at 7:40:27 PM UTC-4, John Larkin wrote: >> On Thu, 10 Oct 2019 16:36:35 -0700 (PDT), whit3rd wrote: >> >> >On Thursday, October 10, 2019 at 7:50:51 AM UTC-7, John Larkin wrote: >> > >> >> I've heard of people using a variac to slowly bring up an old >> >> instrument. >> > >> >A switchmode regulated supply, though, takes maximum current input >> >when voltage is low-to-borderline. So that mainly is good for >> >unregulated power (or power-wasting series or shunt regulated). >> >It's also questionable if there's a DC fan, or ferroresonant circuit... >> >> I meant an OLD instrument. > >Back in the '60 and '70s we would apply 12 to 24 volts to old equipment to warm the power transformer to drive out moisture. The tubes were pulled, first and it was left on this setup for 24 hours. It seemed like every old piece of test equipment was store in a dank basement. > >I had a Sprague TO6 capacitor analyzer that could reform to 500VDC, and it metered the leakage current. If the oxide layer was bad, you could slowly ramp it up until it had acceptable leakage at the rated voltage. The Military had a set schedule to test and reform NOS electrolytics that were in warehouses. I used to see a lot of surplus caps with a label showing the dates.Are modern electrolytics any better than the old ones, from the aspect of un-forming themselves? Or maybe the old ones are, well, just old.
