Hello Peter: According to IEC 384-14, the capacitor types suitable to bridge BASIC INSULATION are Y2, Y3, or Y4 capacitors. According to the voltages you specify, a Y4 cap would be suitable.
The thing to keep in mind here is clause 1.5.3 of IEC 384-14, which defined an X capacitor as: "A capacitor...of a type suitable for use in situations where failure of the capacitor...WOULD NOT lead to danger of electric shock." Also, clause 1.5.1 of EN 60950 - "Where safety is involved, components shall comply with either the requirements of this standard or with the safety aspects of the relevant IEC component standards." Based on your voltages, it appears that you are dealing with a DC distribuition system such as you would find in a Central Office....am I correct in assuming that this is TNV? (It could not be SELV as you are up to 72VDC). If so, then your question no doubt is embedded with concerns from clause 6.3.3 of EN 60950, UL 1950/CSA 950, etc. I have had conversations with various agencies on this issue in the past...some UL engineers I spoken with are of the opinion that any capacitor could be used in this situation so long as the equipment passes the Electric Strength test requirements. However, a number of labs in Europe insist on Y2 capacitors in this situation. My recomendation would be, assuming that my assumptions on the details of your application are correct: 1) Use at least a Y2 capacitor if the geographical area in which the equipment will be installed has a nominal mains supply voltage of greater than 150Vrms. 2) Use at least a Y4 capacitor if the geographical area in which the equipment will be installed has a nominal mains supply voltage of less than 150Vrms. Hope this helps... Regards, Mel mailto:mpeder...@midcom-inc.com -----Original Message----- From: Peter Merguerian [mailto:pmerguer...@itl.co.il] Sent: Thursday, October 05, 2000 4:28 AM To: emc-p...@majordomo.ieee.org Subject: Suitability of X2 Capacitors as Basic Insulation Is it possible to use a 250 Vac X2 approved capacitor as a y capacitor (input to ground) for a unit with an input voltage of 48/60Vdc up to 72Vdc? In other words, is an X2 capacitor suitable for basic insulation? Peter Merguerian Managing Director Product Testing Division I.T.L. (Product Testing) Ltd. Hacharoshet 26, POB 211 Or Yehuda 60251, Israel Tel: 972-3-5339022 Fax: 972-3-5339019 e-mail: pmerguer...@itl.co.il website: http://www.itl.co.il TO LEARN ABOUT AUSTRALIAN AND NEW ZEALAND REQUIREMENTS, CONTACT ME AT THE EARLIEST STAGES OF YOUR DESIGN; REQUIREMENTS CAN BE TRICKY! ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. 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: Jim Bacher: jim_bac...@mail.monarch.com Michael Garretson: pstc_ad...@garretson.org For policy questions, send mail to: Richard Nute: ri...@ieee.org
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