If the fan tray only has a single power source coming in then you kill the power but the fan exhaust ports are still left open. The fan tray failure shouldn't be simulated by either covering all of the exhaust ports and leaving the fans running or, covering all the exhaust ports and the fan power removed - either case constitutes more than one failure - multiple blockages and/or fan tray failure and multiple blockages. I don't have any disagreement with those that would test in-house to determine the effect. I'm just saying the standard identifies only one failure at a time. Gary
From: Stone, Richard [mailto:rst...@xl.com] Sent: Tuesday, November 25, 2003 10:28 AM To: Brian O'Connell; emc-p...@majordomo.ieee.org Subject: RE: Blocked ventillation testing could this be in susbstitution for complete 100% fantray failure? I dont think its vaild, as youd still have openings in the sides if the fans all died... one side at a time is the norm for one fault over heating temperature testing.... unless something new just came up. Richard, Richard A. Stone Excel Switching Corporation Compliance 75 Perseverance Way Hyannis, MA. 02601 508 862 3311 ph. 508 862 3020 fax rst...@xl.com This email message and any attachments to it contain confidential information that is intended only for the person or entity to which it is addressed. Any review, retransmission, dissemination, printing, or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please delete it or inform the sender. From: owner-emc-p...@majordomo.ieee.org [mailto:owner-emc-p...@majordomo.ieee.org]On Behalf Of Brian O'Connell Sent: Tuesday, November 25, 2003 12:28 PM To: emc-p...@majordomo.ieee.org Subject: RE: Blocked ventillation testing At least for 60950-1, this should be considered a multiple fault; unless the intended end-use installation indicates a "mechanical" situation where all vents blocked could be considered a SFC. I am not aware of any National Differences that would allow this test condition. If UL is acting as an NCB, there might be a CTL decision that would indicate otherwise. luck, Brian -----Original Message----- From: Robert Johnson [ mailto:robe...@rcn.com] Sent: Tuesday, November 25, 2003 7:56 AM To: emc-p...@majordomo.ieee.org Subject: Blocked ventillation testing I have been requested by UL-HongKong to the blocked ventillation abnormal testing with all vents on all side blocked simultaneously. My previous experience has been that one side is blocked at a time. Blocking more than one side at a time was considered multiple faults. If it passes blocking all vents at once shortens test time, but is this method necessary? What is the experience of others? Bob Johnson