Greetings, The thing that has to be kept in mind though, is that the "normal operating voltage" is not what is important. What is important is the ringing voltage. The normal operating voltage in North America is only 48 V dc, but when the phone rings, this ringing voltage is nominally 90 V ac. This is not the max, just the NOMINAL voltage. So it is not unreasonable for a certification agency to verify construction based on 125 V ac.
The normal operating voltage in many European telecom systems is 60 V dc. I'm not sure what the ringing voltage is in these systems. Regards, Egon Varju At 10:47 AM 12/10/1998 -0400, you wrote: >This is being cleared up in the third edition of IEC 60950. It has been undefined >in previous versions of the standards. Agencies have each chosen values to use, but >you should be able to argue for the following since most countries have already >agreed to this proposal in their voting on the third edition. > >In 74/484/CDV clause 2.10.4 you will find >"When determining the working voltage for a TNV circuit connected to a >telecommunication network whose characteristics are not known, the normal operating >voltages shall be assumed to be the following values: >- 60 V d.c. for TNV-1 circuits; >- 120 V d.c. for TNV-2 circuits and TNV-3 circuits" > >in 74/484/CDV clause 2.10.3.3 you will find >"If the telecommunicaiton network transient voltage is not known for the >telecommunication network in question, it shall be taken as: >- 1500 Vpeak if the circuit connected to the telecommunication network is a TNV-1 >circuit or a TNV-3 circuit; and >- 800 Vpeak if the circuit is connected to the telecommunication network is a SELV >circuit or a TNV-2 circuit." ______________________________________ Egon H. Varju, PEng E.H. Varju & Associates Ltd. North Vancouver, Canada Tel: 1 604 985 5710 Fax: 1 604 273 5815 E-mail: [email protected] URL: http://www.varju.bc.ca/ ______________________________________ --------- This message is coming from the emc-pstc discussion list. To cancel your subscription, send mail to [email protected] with the single line: "unsubscribe emc-pstc" (without the quotes). For help, send mail to [email protected], [email protected], [email protected], or [email protected] (the list administrators).
