From: Robert Johnson <[email protected]> Subject: Re: RATED VOLTAGE UL1950
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." Larry Barnette wrote: > Dear group, > > I have a question on defining the RATED VOLTAGE that should be applied to > TNV in UL1950 Clause 6.3.3.1 "Additional Test" for "separation between > telecommunication network and earth" (Figure 17) for a Class III device that > operates from an external nominal 12VDC (SELV) Listed Class II Level 3 > adapter. I know by definition RATED VOLTAGE 1.2.1.1 is the primary voltage > as declared by the manufacturer. I see that this is obviously the case if > the power supply is physically part of the equipment and directly mains > powered. In this case it is a seperate module. > > Should I use as the the RATED VOLTAGE for this test the upper limit of the > mains voltage to the adapter (125VAC) or can the test be done at the rated > voltage of the EUT (e.g. 16VDC)? > > If it's the "mains voltage" to the adapter, then in reality its seems we are > re-testing an already Listed and proven adapter where there should be no > more than 0.25ma leakage. > > Your responses are greatly appreciated. > ------------------------------------------------------------------------------- > Larry Barnette > Compliance Engineer > GAI-Tronics Corp. > Memphis Facility > Instrument Associates Division > 2455 Harbor Ave. > Memphis, Tenn. USA 38113 [email protected] > Phone: 901-947-4000 Ext. 176 Fax: 901-948-0471 > -------------------------------------------------------------------- > > --------- > 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).
