| Electronics > Beginners |
| Electrolytic capacitor ESR confusion |
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| valley001:
I am in the process of recapping a Fluke 332D. Once cap has failed on it so far and I would rather not chase bad caps over the next 10 years so I have decided to simply replace as many of the electrolytic as I can (reasonable?) Three of the caps are 450v 8uf +50/-10%. I found KEMET PEG124YF2100QL1 450v 10uf however the quoted ESR is 5.7 ohms. Is this a normal ESR figure for this type of capacitor? My noob impression is that ESR should be less than an ohm. I just want to be sure I install a cap that will work properly. Thanks in advance for the education. |
| helius:
High voltage, low capacitance devices have high ESR as a result of their physical construction. That is perfectly normal. I would probably not replace all capacitors at once because there is a risk of damage with any kind of rework. |
| valley001:
--- Quote from: helius on March 18, 2019, 01:12:48 am ---High voltage, low capacitance devices have high ESR as a result of their physical construction. That is perfectly normal. I would probably not replace all capacitors at once because there is a risk of damage with any kind of rework. --- End quote --- Is this risk lower than a cap going sideways? I worry about a sideways cap taking out other more unobtainable parts. |
| Jay_Diddy_B:
Hi, Less than 1 \$\Omega\$ is a simplification. A lot of commonly encountered values will be less than 1 \$\Omega\$, but if you look at the Kemet datasheet: https://www.mouser.ca/datasheet/2/212/KEM_A4011_PEG124-1104316.pdf You will see that some low capacitance and higher voltage electrolytic capacitors are more than 1 \$\Omega\$ ESR. The Kemet part you have chosen is probably better than the part that was used originally. Do you have a method foe measuring ESR? Regards, Jay_Diddy_B |
| valley001:
Thanks everyone for chiming in. I use one of those cheap component testers for measuring ESR. |
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