Oil Capacitor DC vs. AC Voltage Rating

valveitude · 10th June 2005, 10:08 PM

Can someone tell me how to determine the DC rating based on the AC rating of oil caps. I assumed it would be 1.414 the AC rating, but I've seen several caps listed with the DC being 2 or more times the AC. What gives?

Thanx,
Casey

pedroskova · 10th June 2005, 11:07 PM

If you're talking about ASC or GE motor run caps, 1.4x AC rating would be pretty conservative. I think a GE engineer told someone that the 440V motor runs were safe with 1000VDC. I wouldn't do that, but it's an indicator of sorts.

Sherman · 11th June 2005, 12:45 AM

Quote:

Originally posted by pedroskova
If you're talking about ASC or GE motor run caps, 1.4x AC rating would be pretty conservative. I think a GE engineer told someone that the 440V motor runs were safe with 1000VDC. I wouldn't do that, but it's an indicator of sorts.

I was also told that doubling the AC voltage rating of ASC caps for DC was safe. However when I built a pair of power supplies using them I went with 1.4x as a maximum!

10th June 2005, 10:08 PM	#1
valveitude diyAudio Member Join Date: Apr 2005 Location: Naches,WA	Oil Capacitor DC vs. AC Voltage Rating Can someone tell me how to determine the DC rating based on the AC rating of oil caps. I assumed it would be 1.414 the AC rating, but I've seen several caps listed with the DC being 2 or more times the AC. What gives? Thanx, Casey __________________ Experience is a wonderful thing. It enables you to recognize a mistake when you make it again.

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10th June 2005, 11:07 PM	#2
pedroskova RIP Join Date: Dec 2002 Location: C'ville VA, USA	If you're talking about ASC or GE motor run caps, 1.4x AC rating would be pretty conservative. I think a GE engineer told someone that the 440V motor runs were safe with 1000VDC. I wouldn't do that, but it's an indicator of sorts.

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