John, According to IEC664 (and as a result, all derived standards), altitude correction is normalized to 2000 meters (6562 feet) for a nominal barometric pressure of 80 kPa. This calculation is based on Paschen's Law and covers most of the populated areas of the world. This altitude correction is intended for the calculation of clearances to give sufficient spacing for impulse withstand up to 2000 meters. It is not for adjustment test voltages. Additionally, IEC664 does not mention the concept of derating for lower altitudes only higher.
I also understand that it is possible to use a lower level for a product, but only if you are certain that the end use of the product will always be at the lower altitude or less. You would also need to indicate in the operating documents, a "condition of use" that the product never be put into service at an altitude higher that the 0.816 correction that you mention. If my numbers are correct you are attempting to test at 1632 meters (5354 feet). Are you at Lucent in Westminster Colorado? I am in Ft. Collins Colorado and have been asked similar questions from engineers. It has generally been my policy to leave altitude correction at the default 2000 meters unless the equipment is required to go to a higher altitude for service. And in one instance the customer specification required 2500 meters. -doug ================================= Douglas E. Powell Regulatory Compliance Engineer Advanced Energy Industries, Inc. 1625 Sharp Point Dr. Ft. Collins, Co 80525 mailto:[email protected] http:\\www.advanced-energy.com\ ================================= -----Original Message----- From: Boucher, John [mailto:[email protected]] Sent: Friday, June 02, 2000 3:35 PM To: '[email protected]' Subject: High voltage testing and altitude correction factor All: I work for a test lab located approximately one mile above sea-level, and perform product safety testing on IT and telecommunications equipment (IEC 60950 and clones). I recently tested a telecom interface PWB that failed 6.4 HV testing (case c, 1.0kv). The PWB failed at approximately 900 volts. The PWB passed a re-test performed at an altitude correction factor (0.816). I know that clause 5.3 allows for altitude correction, but the standards dont mention any correction factors with regard to clause 6.4. Have any of you good people used altitude correction for clause 6.4 testing on international products? Any comments from you agency types? (yeah, you're good people too) Thanks. John Boucher Lucent Technologies ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected] ------------------------------------------- This message is from the IEEE EMC Society Product Safety Technical Committee emc-pstc discussion list. To cancel your subscription, send mail to: [email protected] with the single line: unsubscribe emc-pstc For help, send mail to the list administrators: Jim Bacher: [email protected] Michael Garretson: [email protected] For policy questions, send mail to: Richard Nute: [email protected]
