Is there any equipment to measure dv/dt of capacitor?

[GSiu]

Is there any equipment to measure dv/dt of capacitor?

 

[Jim Thompson]

Is there any equipment to measure dv/dt of capacitor?

Bwahahahahahahaha! ROTFLMAO!

...Jim Thompson

 

[J.A. Legris]

Is there any equipment to measure dv/dt of capacitor?

What are you trying to do?

 

[Steveo]

Um, have you tried an oscilloscope?

 

[Eeyore]

Is there any equipment to measure dv/dt of capacitor?

MMmmmm......... Interesting !

Why / what do you want to know?

Graham

 

[budgie]

Is there any equipment to measure dv/dt of capacitor?

It's called an ammeter ....

 

[Phil Allison]

"GSiu"

Is there any equipment to measure dv/dt of capacitor?

** The dv/dt rating ( aka pulse current rating) of a capacitor is usually
quoted in the specifications.

It is not a simple measurement ( like capacitance value) but a performance
rating which maker is confident the parts he supplies can meet on a long
term basis.

If you want to determine the maximum " dv/dt " being experienced by a cap -
monitor the current flowing through the cap with a scope and series sense
resistor and use the formula:

dv/dt = I / C

Eg:

10 amp current spikes flowing through a 100nF cap = 100 volts /uS



....... Phil

 

[GSiu]

What are you trying to do?

Need a equipment to measure dv/dt of capacitor - for QC purpose and
engineering test.
Capacitor from USA and China claim have the same dv/dt, but the price
level is not the same.
If there is equipment to measure those China made film capacitors, then
can purchase lower cost capacitors from China.

Kind Rgds,
GSiu

 

[Genome]

Need a equipment to measure dv/dt of capacitor - for QC purpose and
engineering test.
Capacitor from USA and China claim have the same dv/dt, but the price
level is not the same.
If there is equipment to measure those China made film capacitors, then
can purchase lower cost capacitors from China.

Kind Rgds,
GSiu

You would probably have to do some sort of highly accelerated liftime test.
HALT.

Take samples from each manufacturer nad make measurements on the parameters
the manufacturers use to define failure.

Ovenise them to their highest operating temperature, use the same for both
samples. Apply a square wave bipolar current drive to achieve the maximum
specified dV/dT. Adjust the frequency to drive the capacitor voltage to the
rated value.

Run the test for 'some' time (up to a week) and then take the same
measurements again.

If there is no significant change then double the dV/dT, double the
frequency to maintain the same peak voltage, and run the test again. Use
'new' capacitors each time. Keep increasing the dV/dT and iterate until
something significant starts to go wrong.

At some point you will be able to characterise things so you can specify the
parameters for your own version of a HALT test for film capacitors. Once you
have those parameters use them on a sample of capacitors from each
manufacturer and compare performance.

DNA

 

[Phil Allison]

"Genome"
"GSiu"

You would probably have to do some sort of highly accelerated liftime
test. HALT.

Take samples from each manufacturer nad make measurements on the
parameters the manufacturers use to define failure.

** If there are significant doubts about the credibility of published specs,
quality control, consistency and reliability of the Chinese caps then DO
NOT buy them.

Only a *complete fool* imagines such things are ascertained by a testing a
few samples with any sort machine.

Seems you qualify.






....... Phil

 

[Genome]

"Genome"
"GSiu"


** If there are significant doubts about the credibility of published
specs, quality control, consistency and reliability of the Chinese caps
then DO NOT buy them.

If the capacitors being offered offer a cost saving that exceeds the cost of
verifying the quoted performance figures then test them. Assuming that
performance cannot be verified by other means. If continued confidence
cannot be gauranteed and the savings are still available then make the
testing an ongoing process. In volume manufacture the results can be
significant.

Obviously since you have only designed two things in your life and only one
of them worked and only one of them was built you would not have been worth
the 4 cents that might have been saved.

Only a *complete fool* imagines such things are ascertained by a testing
a few samples with any sort machine.

Then how did the manufacturers verify the figures they give in the first
place. Are you suggesting that they just guessed and published them. You
don't think they might have tested some samples do you. You don't suppose
they have an ongoing quality control method where they sample and test
things to ensure that what they are producing is what they claim it to be.

Seems you qualify.

Well, thank you very much. I'm glad I pass the Phil Allison test for being a
*complete fool*. Incidentally are there any published methods and procedures
that you use to Qualify the award of such a title?

...... Phil

Ah yes, that would be the Phil who had the job before and now everything is
broken and needs fixing. You mean you didn't sack him, he just sort of blew
up and didn't turn up for work one day.

DNA

 

[Phil Allison]

"Genome ASD"
"GSiu"

If the capacitors being offered offer a cost saving that exceeds the cost
of verifying the quoted performance figures then test them.

** Obviously you cannot read, let alone think.

Then how did the manufacturers verify the figures they give in the first
place.

** Irrelevant to speculate about.

The OP doubts the published specs so has no faith in the maker = DON' T
BUY THEM.

The potential financial harm if the caps do prove to have a high failure
rate in service is ENORMOUS.

Well, thank you very much.

** That remark was aimed at the OP.

BTW:

Psychotic piles of sub human garbage like "Genome" can go **** a dead
donkey.






....... Phil

 

[colin]

Is there any equipment to measure dv/dt of capacitor?

A current probe for an oscilloscope. as i=c.dv/dt
is it for a snubber ?

Colin.

 

[Spehro Pefhany]

Is there any equipment to measure dv/dt of capacitor?

Perhaps these are for mains use, or you might not be so concerned
about this particular characteristic. Are there any safety agency
approvals on the parts? You might want to validate them and check what
tests were performed. They use large lots for such tests (hundreds of
pieces and long-term accelerated testing at high temperature).

Exceeding the maximum dv/dt can just burn off little bits of
metallization and won't necessarily show itself immediately in an
obvious way.

Chances are if the construction and matererials are similar, the max
dv/dt characteristics will be similar.

 

[ian field]

Bwahahahahahahaha! ROTFLMAO!

...Jim Thompson

Some capacitors have this parameter specified, such as the types intended
for flyback tuning in CRT displays. Possibly the most revealing test is to
incorporate the cap into a high power LC circuit and asses its performance
when the slope of the waveform approximates to the dv/dt spec on the
datasheet.

 

[ian field]

"Genome ASD"
"GSiu"


** Obviously you cannot read, let alone think.





** Irrelevant to speculate about.

The OP doubts the published specs so has no faith in the maker = DON' T
BUY THEM.

The potential financial harm if the caps do prove to have a high failure
rate in service is ENORMOUS.





** That remark was aimed at the OP.

BTW:

Psychotic piles of sub human garbage like "Genome" can go **** a dead
donkey.






...... Phil

How's Genome's not washing marathon going? - maybe the dead donkey smells
better!

 

[Jim Thompson]

Some capacitors have this parameter specified, such as the types intended
for flyback tuning in CRT displays. Possibly the most revealing test is to
incorporate the cap into a high power LC circuit and asses its performance
when the slope of the waveform approximates to the dv/dt spec on the
datasheet.

Some capacitors may well have a specification for MAXIMUM RATED dv/dt
before dielectric failure; but the OP didn't ask that... unless, of
course, he has no clue ;-)

...Jim Thompson

 

[Genome]

How's Genome's not washing marathon going? - maybe the dead donkey smells
better!

Got a bit sweaty during the hot weather type stuff and had to resort to
Canestan to clear up the red halo around my arsehole.

There are a few crotch pores building up plugs but nothing worth harvesting
for a chew yet.

DNA

 

[Genome]

Some capacitors may well have a specification for MAXIMUM RATED dv/dt
before dielectric failure; but the OP didn't ask that... unless, of
course, he has no clue ;-)

...Jim Thompson

You're just trying to make excuses for going BwaaaHaaHaaHaa.....

DNA

 

[Jim Thompson]

You're just trying to make excuses for going BwaaaHaaHaaHaa.....

DNA

;-)

...Jim Thompson