On Fri, 6 Sep 2002 16:19:52 +0900, "Michael Jang" <mich...@certitek.com> wrote:
> I have a question for "Discharge of capacitors in the primary circuit' > (Related to 60950 standard) > > ----Standard ------------------------------------------------ > Equipment is considered to comply if any capacitor having a marked or nominal > capacitance exceeding 0.1 uF and connected to the PRIMARY CIRCUIT has a > means of discharge resulting in a time constant not exceeding: > - 1 s for Pluggable equipment type A; and > - 10 s for Permanently connected equipment and for pluggable equipment type B. > --------------------------------------------------- > > Why does not consider up to 0.1 uF? # maybe too late, but... I think we can apply the limits for Limited Current Circuit to capacitors connected to the primary circuit, too, and capacitors up to 0.1uF are considered there. A capacitor which: - capacitance <= 0.1uF for voltage <= 450V, or - stored charge <= 45uC for 450V < voltage <= 15kV, or - stored energy <= 350mJ for 15kV < voltage. will become a Limited Current Circuit (2.4.1). So, for voltage up to 450V d.c. (i.e. up to 318V a.c.), capacitor up to 0.1uF will become a Limited Current Circuit, hence the voltage is not Hazardous Voltage (1.2.8.4) - no additional condition would be required for the capacitor connected to the primary circuit. However, capacitor larger than 0.1uF would not comply with the requirements for Limited Current Circuit, and the voltage could be thought as Hazardous Voltage. I think that is why the discharge requirement which, under certain condition, allow capacitor exceeding 0.1uF connected to the primary circuit was specified. Regards, Tom -------------------------------------------------- Tomonori Sato <vef00...@nifty.ne.jp> URL: http://member.nifty.ne.jp/tsato/ ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. Visit our web site at: http://www.ewh.ieee.org/soc/emcs/pstc/ To cancel your subscription, send mail to: majord...@ieee.org with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Ron Pickard: emc-p...@hypercom.com Dave Heald: davehe...@attbi.com For policy questions, send mail to: Richard Nute: ri...@ieee.org Jim Bacher: j.bac...@ieee.org All emc-pstc postings are archived and searchable on the web at: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
