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Associate

Join Date: Apr 2010
Posts: 30

How we can check the value of High value capacitor?

06/18/2010 3:13 AM

We have a 10,000 micro farad capacitor DC, and we are using fora long time, now i want to check the value of it, but we have a meter which is maximum range is 3000 micro farad.

Any body tell me another proceedure that i could be check the capacitor value.

it is DC capacitor and working voltage 63 to 100.

Munawer Hussain,

June,18,2010

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Guru

Join Date: Jul 2007
Posts: 4448
Good Answers: 143
#1

Re: How we can check the value of High value capacitor?

06/18/2010 9:14 AM

If it's a high quality cap, and you can settle for 80% accuracy, just do an RC measurement.

If you must use your meter, do you have perhaps 5 or 6 similar values caps? Put them in series (minus 1 each time) and do a matrix.

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Associate

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Posts: 30
#2
In reply to #1

Re: How we can check the value of High value capacitor?

06/19/2010 12:35 AM

Thanks for responding,

Dear sir,

Do you have the the RC circuit for checking the values? Please give me instruction for checking.

Thanks and regards,

Munawer Hussain,

June19,2010

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Guru

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Posts: 4448
Good Answers: 143
#3
In reply to #2

Re: How we can check the value of High value capacitor?

06/19/2010 7:27 AM

Just do an RC discharge time constant check. Charge the capacitor to, say, 24 V, hook it in series with a 4700 Ω resistor, measure the voltage across the resistor, and start timing when you close the circuit. Take voltage readings every ten seconds, put the results in Excel and do a sixth order polynomial. You'll get a time constant between 40 seconds and 60 seconds. Divide by 4700 (actually measure this resistor with a good Ohmmeter), and you'll have the capacitor value.

Look here if you're unsure about doing this. In an ideal world the charge and discharge times are equal. That doesn't work in the real world, and I prefer the discharge value. But, use whichever you like.

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"Well, I've wrestled with reality for 35 years, Doctor, and I'm happy to state I finally won out over it." Elwood P. Dowd
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Anonymous Poster
#4

Re: How we can check the value of High value capacitor?

06/28/2010 5:10 PM

Mesure a capacitor with a value near your instrument's max value. Connect it in series with your unknown capacitor and mesure the combined capacitance. Do the math. Can go really close to the actual value. 53 2E 4D 2E

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