Peter Thanks for that - quite a different background to how it seemed to read to me!
But in that case it does seem a bit of a "brutal" test to apply to guard against a hazard caused solely by a telecomms-circuit source - surely a relatively low power source would be appropriate? Any idea why they did not more closely specify the equipment to be used? Regards Johh Allen -----Original Message----- From: Peter L. Tarver [mailto:[email protected]] Sent: 12 December 2002 16:04 To: John Allen; [email protected] Subject: RE: TNV Test Generator John, et al - No this is not the power cross test, which is described in Annex NAC of CSA/UL60950, third ed. This test is intended to simulate continuous ringing from the network, is akin the an SELV reliability test and, IIRC, was added to the base IEC 60950 standard at the behest of the French, due to limitations in their ability to guarantee cadenced ringing at all locations in their networks. Don Boroski is correct about test setup, though I'd use a variable autotransformer after an isolation transformer to set the voltage, rather than just taking it off of the line. As to real world power cross, on 15NON2000 I forwarded an unedited copy of a usenet posting containing a link to the Orange County on 15NOV2000, where power cross caused "some small fires" and fire fighters evacuated several homes. Because my post is not in the mindcruiser archive and the link in it to the newspaper article is now broken, I've placed a copy in the Info Pieces in the telecom general topics category on the mindcruiser site. The poster's remarks are also very interesting. Regards, Peter L. Tarver, PE Product Safety Manager Sanmina-SCI Homologation Services San Jose, CA [email protected] _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com ************************************************************************* Copyright ERA Technology Ltd. 2002. (www.era.co.uk). All rights reserved. The information supplied in this Commercial Communication should be treated in confidence. No liability whatsoever is accepted for any loss or damage suffered as a result of accessing this message or any attachments. _____________________________________________________________________ This e-mail has been scanned for viruses by the WorldCom Internet Managed Scanning Service - powered by MessageLabs. For further information visit http://www.worldcom.com ------------------------------------------- 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: Ron Pickard: [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: http://ieeepstc.mindcruiser.com/ Click on "browse" and then "emc-pstc mailing list"
