Capacitor voltages? - UK Vintage Radio Repair and Restoration Discussion Forum

Oldelectronics · 19th Oct 2017, 10:38 pm

I silly question but some non electrolytic yellow poly capacitors are marked for example 630v and some 630v DC I assume these are both the same so I thought I would ask as its niggling at me!!

Cheers

Kev

Philips210 · 19th Oct 2017, 10:45 pm

Hi.

From my understanding the voltage rating of a capacitor is the DC rating unless otherwise marked in which case it will be marked as 400Vac for example to indicate it's AC rating.

Regards
Symon

Oldelectronics · 19th Oct 2017, 10:47 pm

I think I have answered my own question looking at a thread on X/Y capacitors which the working voltage is AC and all others the working voltages are DC

Oldelectronics · 19th Oct 2017, 11:11 pm

Thanks Symon our post crossed! Thank you for confirming that, its much appreciated

Regards

Kev

paulsherwin · 19th Oct 2017, 11:31 pm

Yes, always assume the rating is DC unless it is clearly marked AC. The DC rating will always be higher than the AC rating.

Maarten · 20th Oct 2017, 2:37 am

Rule of thumb says: if no AC value is given, assume a factor 3 lower than the DC value (actually 2 times sqrt 2) and no high dV/dt applied unless it's a polypropylene capacitor.

Oldelectronics · 20th Oct 2017, 2:39 pm

Thanks Guys much appreciated.

Kev

19th Oct 2017, 10:38 pm	#1
Oldelectronics Heptode Join Date: Jan 2016 Location: Nottinghamshire, UK. Posts: 676	Capacitor voltages? I silly question but some non electrolytic yellow poly capacitors are marked for example 630v and some 630v DC I assume these are both the same so I thought I would ask as its niggling at me!! Cheers Kev

19th Oct 2017, 10:45 pm	#2
Philips210 Nonode Join Date: May 2007 Location: Redruth, Cornwall, UK. Posts: 2,573	Re: Capacitor voltages? Hi. From my understanding the voltage rating of a capacitor is the DC rating unless otherwise marked in which case it will be marked as 400Vac for example to indicate it's AC rating. Regards Symon

19th Oct 2017, 10:47 pm	#3
Oldelectronics Heptode Join Date: Jan 2016 Location: Nottinghamshire, UK. Posts: 676	Re: Capacitor voltages? I think I have answered my own question looking at a thread on X/Y capacitors which the working voltage is AC and all others the working voltages are DC

19th Oct 2017, 11:11 pm	#4
Oldelectronics Heptode Join Date: Jan 2016 Location: Nottinghamshire, UK. Posts: 676	Re: Capacitor voltages? Thanks Symon our post crossed! Thank you for confirming that, its much appreciated Regards Kev

19th Oct 2017, 11:31 pm	#5
paulsherwin Moderator Join Date: Jun 2003 Location: Oxford, UK Posts: 27,934	Re: Capacitor voltages? Yes, always assume the rating is DC unless it is clearly marked AC. The DC rating will always be higher than the AC rating.

20th Oct 2017, 2:37 am	#6
Maarten Dekatron Join Date: Dec 2007 Location: Haarlem, Netherlands Posts: 4,199	Re: Capacitor voltages? Rule of thumb says: if no AC value is given, assume a factor 3 lower than the DC value (actually 2 times sqrt 2) and no high dV/dt applied unless it's a polypropylene capacitor.

20th Oct 2017, 2:39 pm	#7
Oldelectronics Heptode Join Date: Jan 2016 Location: Nottinghamshire, UK. Posts: 676	Re: Capacitor voltages? Thanks Guys much appreciated. Kev