My product is rated 32 - 72 VDC in order to be compatable with a Telco system operating at 60VDC (72V when charging according to all of the telecom standards I have read). This "Filter" is to be considered a component of a telco system....it is used to power the telecom equipment. From what I have been reading to date, it seems that the earthing rules do not apply here because this product cannot be classified as a telecom network.....it is only part of the power plant distribution system. Also, the DC return is always directly connected to earth in such a system. Annex NAB in UL60950 seems to explain it very well. What do you think?
Ed
>From: "Stone, Richard A (Richard)"
>To: "'Ed Eszlari'"
>Subject: RE: TNV-2 to Earth requirement
>Date: Mon, 28 Jan 2002 13:03:48 -0500
>
>the filter rating, is it component level or your product itself?
>if your 40-60vdc, restrictions are lowered.
>Check your desired application.
>Richard,
>
>-----Original Message-----
>From: Ed Eszlari [mailto:bosesaf...@hotmail.com]
>Sent: Thursday, January 17, 2002 10:44 AM
>To: treg@world.std.com; emc-p...@ieee.org
>Subject: TNV-2 to Earth requirement
>
>
>All,
>
>I have a DC to DC "filter" which is rated 32 - 72 VDC input and output which
>I am considering to be TNV-2 according to EN60950/IEC60950 2nd edition.
>
>This filter has a metal chassis which is earthed, and it will be installed
>in a service access area only by qualified service personnel. It is not
>permanently connected or pluggable type B, and does not have a provision for
>a permanently connected earthing conductor. With all this considered, it
>seems that Norway and Sweden are the only Countries that require
>Supplemental insulation for a primary circuit between this TNV-2 circuit and
>earth.
>Is there any way around this requirement due to this filter operating at
>72VDC and not being directly connected to mains?
>
>Any help would be appreciated.
>
>Ed
>
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