Jim, Protection arrangements use parallel components for overvoltage protection and series components for overcurrent protection.
The gas discharge tube is fine to protect against overvoltages. You also need overcurrent protection, a series PTC like the Raychem TR or TS series will prevent the simulator fuse from blowing. Check out Conformity September 1999, there is a good article on power cross protection. Regards, David. David Gelfand Regulatory Approvals Memotec Communications Inc. Montreal Canada ----- Original Message ----- From: "Lyons, Jim" <[email protected]> To: <[email protected]> Sent: Thursday, November 30, 2000 1:43 PM Subject: Telecom/Safety Question > Underwriters Laboratories is testing an ITE product for me that uses a > three terminal 400V gas tube between tip, earth and ring of the telecom > connection. They have failed the NAC M1 test (600V, 40A, 1.5sec) because > the 2 amp fuse used in the wiring simulator (figure NAC.2 in UL1950 3rd > page 239) opened during the test. > > The gas tube would look pretty much like a short circuit once it starts to > conduct, and I would expect the Buss MDL2 fuse they used to blow. Their > failure criteria would seem to exclude the use of gas tubes directly > across the tip and ring lines. Is this a proper assumption? > > I would appreciate any thoughts on this situation. > > Jim Lyons > > James W. Lyons > Manager - Product Compliance > GTECH Corp. > 55 Technology Way > West Greenwich, RI 02817 > Tel (401) 392-7723 > Fax (401) 392-4955 > Email [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] ------------------------------------------- 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]
