参考PAG clause 2.10.2-3 Working voltages in TNV circuits
* o- Y9 Q8 @2 r7 u7 d4 cIf the equipment generates a ringing signal and the circuit connects to a Telecommunication
1 [7 e4 }7 [( HNetwork, the working voltage should be measured in accordance with sub-clause 2.10.4 and5 x4 k7 y6 V; s, L- \: Z5 N+ f- n( t
Annex M.3.1 to determine maximum peak, rms and/or dc values.
* u7 e F% Z! h* i' c3 RIf the equipment is intended for connection to a U.S./Canadian Telecommunication Network and( K. {% Z9 i+ m3 ~! s5 `, ?& s& Q
receives incoming analog telecommunication signals (e.g., from a Central Office), the following
" N9 I4 S6 s: _; M0 H' f7 Amaximum working voltages (TNV-3) should be assumed for purposes of determining required
; s1 w/ s( C) Q4 H: bclearances, creepage distances and electric strength test values:
% ~( K* \+ u, H! Ua. peak: 200 V' m( R; g/ \" s7 G9 k0 _/ B
b. rms: 120 V
+ X6 C& I1 \ @' g+ Jc. d.c.: 60 V# ^1 j2 {) U# s' T" ^
176 PAG 60950-1 JULY 15, 20086 D8 S! t$ p9 G0 D
If the equipment is intended for connection to a European Telecommunication Network, consult0 p: @( b3 H* n8 I. T& s7 _
with IEC TR 62102, Technical Report on Electrical Safety Classification of interfaces for
: f- o( W2 l: @ Vequipment to be connected to information and communications technology networks.
8 Z0 Q2 [) m6 nThe peak and rms values are used for clearance and electric strength determinations, and the
* ~1 ?: O, S! M" F9 `. T; ed.c. value is used for creepage distance.
/ n0 [. i. v3 XRATIONALE:+ l% X9 x" D4 g
Annex M (normative) describes maximum voltage levels associated with Telecommunication
0 Q$ N A8 v$ I( [+ A% qSignals that comply with FCC Part 68. The maximum peak value specified is 200 V referenced
/ A2 t( T8 U) M) Rto earth. Since working voltages typically are measured to earth, this value should be considered
* z7 f" z i7 |. `1 B4 A% tthe maximum peak value in the U.S. and Canada.5 H$ U( e7 F1 {" {9 D7 x- F% g
Although Annex M does not contain a corresponding rms value, 120 V rms is an approximation
1 p; y& B' i) `# Iof a composite 56.5 V dc and 300 Vp-p signal. Sub-clause 2.3.5 uses 120 V rms to simulate7 r0 O" u e7 v" D$ D- o) V
externally generated operating voltages. Therefore this value should be used for investigation to$ Q' Q- N8 V$ Z9 a
this Standard. Also, sub-clause 2.10.4 indicates that cadenced ringing signals in TNV circuits9 p% D/ T2 p, ?3 L$ h
shall not be taken into account for determining creepage distances, thus a 60 Vd.c. value may, Z" D9 V0 |6 ]& L7 b C% X7 w
be used.6 D! B* t9 C4 B4 m8 s1 x
根据class III equipment定义的条款! g: l$ O+ t a& {
1.2.4.3 CLASS III EQUIPMENT: equipment in which protection against electric shock relies upon
) L$ L8 q9 w, |5 Xsupply from SELV CIRCUITS and in which HAZARDOUS VOLTAGES are not generated/ P( C, x# |$ x: L
NOTE For CLASS III EQUIPMENT, although there is no requirement for protection against electric shock, all other requirements of the standard apply.
1 P, S, y+ z, G8 v- @' w% ~1 ?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。
$ d! e& ~+ B# y$ n欢迎拍砖" R/ ^* d `5 I/ k
0 q- w8 q. X8 P' r
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