There are many EMI filters on the market with a discharge resistor across line and neutral to discharge the capacitor(s). The filter we use has a one megohm resistor built in.
IEC60950 requires that capacitor exceeding 0.1uF should have a means of discharge resulting in a time constant not exceeding 1 second for pluggable equipment Type A. At one time we used a filter which was just below 0.1uF, and therefore didn't need a discharge resistor. It may have complied with the standard, but you certainly felt it if you grabbed the plug pins too quickly. Regards, John Crabb, Development Excellence (Product Safety) , NCR Financial Solutions Group Ltd., Kingsway West, Dundee, Scotland. DD2 3XX E-Mail :[email protected] Tel: +44 (0)1382-592289 (direct ). Fax +44 (0)1382-622243. VoicePlus 6-341-2289. -----Original Message----- From: [email protected] [mailto:[email protected]] Sent: 26 October 2001 12:42 To: [email protected] Subject: EMI filter hazards Many of us incorporate these little babies in our designs, and good design practices require their placement at the enclosure threshhold to prevent re-radiation. This sometimes means the filter is upstream of the/any mains switch or breaker. In these cases, what can be done to mitigate the shock risk at the equipment plug for those first seconds after removal? We warn our customers at the mains terminals and in the manual, but, still.... ------------------------------------------- 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: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Michael Garretson: [email protected] Dave Heald [email protected] For policy questions, send mail to: Richard Nute: [email protected] Jim Bacher: [email protected] All emc-pstc postings are archived and searchable on the web at: No longer online until our new server is brought online and the old messages are imported into the new server.
