参考PAG clause 2.10.2-3 Working voltages in TNV circuits0 [) v! Y; u! ^2 T2 p
If the equipment generates a ringing signal and the circuit connects to a Telecommunication
5 j. o% [' E7 G) A- nNetwork, the working voltage should be measured in accordance with sub-clause 2.10.4 and# h+ v, @* n2 i2 u8 b: U H& k8 R
Annex M.3.1 to determine maximum peak, rms and/or dc values.
0 u7 c$ f) O6 M7 F: |If the equipment is intended for connection to a U.S./Canadian Telecommunication Network and
" A. W, m1 e$ F- c! J. f: X, ^receives incoming analog telecommunication signals (e.g., from a Central Office), the following
- E& J* j& k% B. C/ L" Z' ?" _$ d+ Fmaximum working voltages (TNV-3) should be assumed for purposes of determining required8 u; `- P7 j4 V5 {/ X1 Y
clearances, creepage distances and electric strength test values:9 K/ M: ?) y3 y/ Z6 q
a. peak: 200 V& V+ M ~* X" ]2 |# i4 N
b. rms: 120 V0 L/ ]6 ?8 a9 C7 N2 T4 U; `
c. d.c.: 60 V
( c. D" f5 R }& ?7 p176 PAG 60950-1 JULY 15, 2008
- M5 j7 J* `! W' r, A# A( C: i3 }If the equipment is intended for connection to a European Telecommunication Network, consult
0 `2 q! v1 r0 ~& L; z' U0 Uwith IEC TR 62102, Technical Report on Electrical Safety Classification of interfaces for: s6 F' e" ^' q" ~/ }# j9 ^% T) ~
equipment to be connected to information and communications technology networks.5 C2 _* k/ \# m# P0 K4 |
The peak and rms values are used for clearance and electric strength determinations, and the
% l) h0 l7 a% n$ O( q8 p/ [" Vd.c. value is used for creepage distance.
; A/ D* \8 `% E* f0 S$ }RATIONALE:- T- R: T3 O- j7 h" {+ X! L4 `
Annex M (normative) describes maximum voltage levels associated with Telecommunication
; ~* I3 [ p: r" aSignals that comply with FCC Part 68. The maximum peak value specified is 200 V referenced
) { E2 Q( g8 f+ x+ a1 _, Z$ Fto earth. Since working voltages typically are measured to earth, this value should be considered" K( S" J8 l, \; T
the maximum peak value in the U.S. and Canada.
! t- y$ D9 }( C4 yAlthough Annex M does not contain a corresponding rms value, 120 V rms is an approximation2 G5 }- R: o8 v! M
of a composite 56.5 V dc and 300 Vp-p signal. Sub-clause 2.3.5 uses 120 V rms to simulate a0 a7 h" l, u# A4 G: w
externally generated operating voltages. Therefore this value should be used for investigation to
0 O; Z# e0 ?4 |3 Mthis Standard. Also, sub-clause 2.10.4 indicates that cadenced ringing signals in TNV circuits2 c( n* v& q6 M! ^' Z% i( u
shall not be taken into account for determining creepage distances, thus a 60 Vd.c. value may% O& @" { H# `6 L/ w
be used.
* B# X+ Y; C: v4 d" {8 T+ M4 U3 v* P根据class III equipment定义的条款) c# u, L8 g: V9 \3 Y& F" {3 b
1.2.4.3 CLASS III EQUIPMENT: equipment in which protection against electric shock relies upon
5 l5 P6 Q8 v0 Y% y+ Y ]6 q, V; esupply from SELV CIRCUITS and in which HAZARDOUS VOLTAGES are not generated
0 }" k1 h8 h0 N3 h4 n* J: {NOTE For CLASS III EQUIPMENT, although there is no requirement for protection against electric shock, all other requirements of the standard apply.
" f+ B+ p* h" n我认为应属TNV-3的设备也应属CLASS III，因为其只是接受来自上游的Ring singal，不是自己内部产生。0 C: w8 y, b1 V2 Z- V
欢迎拍砖% w) S4 f$ y7 E7 }$ t. l5 p6 K! N
1 T4 f# p2 w& n! S/ S2 e$ H
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