参考PAG clause 2.10.2-3 Working voltages in TNV circuits' d. }) d3 Z7 K) E1 j( d1 o
If the equipment generates a ringing signal and the circuit connects to a Telecommunication$ q/ k1 k2 f) V3 c3 r
Network, the working voltage should be measured in accordance with sub-clause 2.10.4 and" l; i( L. t1 S5 G
Annex M.3.1 to determine maximum peak, rms and/or dc values., U: F- r% D. ] H
If the equipment is intended for connection to a U.S./Canadian Telecommunication Network and
( e7 F$ m9 h2 X. _1 N5 kreceives incoming analog telecommunication signals (e.g., from a Central Office), the following7 C* x2 r. u1 K. p
maximum working voltages (TNV-3) should be assumed for purposes of determining required+ ^6 R0 ^8 t3 A5 B) m; H4 H
clearances, creepage distances and electric strength test values:
' V5 y& {1 Y: _- |7 ^a. peak: 200 V
: o9 v1 v/ }: M/ wb. rms: 120 V! F2 l \% k/ u$ ?
c. d.c.: 60 V
6 L6 K( {7 B( g( E. d176 PAG 60950-1 JULY 15, 2008
* ?$ L4 S! H1 l5 A3 g8 t# Z$ \ t7 BIf the equipment is intended for connection to a European Telecommunication Network, consult
; n4 T7 u i- }- q; |with IEC TR 62102, Technical Report on Electrical Safety Classification of interfaces for1 `0 o% b5 [3 O5 G- W! ?3 m* y
equipment to be connected to information and communications technology networks.+ ?$ Y* k: c% G7 x0 n7 X
The peak and rms values are used for clearance and electric strength determinations, and the/ M8 }. u6 `! G. {
d.c. value is used for creepage distance.& ?/ `& W) ]% s% L' ]
RATIONALE:
0 I& F( C4 b0 h" s/ aAnnex M (normative) describes maximum voltage levels associated with Telecommunication- j$ X! K" R: a4 \
Signals that comply with FCC Part 68. The maximum peak value specified is 200 V referenced
9 i! {8 Q$ m! ~% Q- o' \. uto earth. Since working voltages typically are measured to earth, this value should be considered1 V4 v. E/ z0 f0 b1 n
the maximum peak value in the U.S. and Canada.$ G3 z% M7 M: U- o4 |
Although Annex M does not contain a corresponding rms value, 120 V rms is an approximation9 Z" V- r& p0 F* j* I2 U9 M
of a composite 56.5 V dc and 300 Vp-p signal. Sub-clause 2.3.5 uses 120 V rms to simulate j4 H( N9 g9 Q D; |2 a+ H
externally generated operating voltages. Therefore this value should be used for investigation to
6 L2 A( ~: K# othis Standard. Also, sub-clause 2.10.4 indicates that cadenced ringing signals in TNV circuits) a5 F3 |7 }$ m% ]$ y. J
shall not be taken into account for determining creepage distances, thus a 60 Vd.c. value may) a' e) ?( r& t0 q9 m, u
be used.
( J9 O9 \; N# X( `根据class III equipment定义的条款+ e: v; C! O" C
1.2.4.3 CLASS III EQUIPMENT: equipment in which protection against electric shock relies upon0 T* ^4 K* A. t* J, F4 t& r) B
supply from SELV CIRCUITS and in which HAZARDOUS VOLTAGES are not generated! M( n3 m0 p Q
NOTE For CLASS III EQUIPMENT, although there is no requirement for protection against electric shock, all other requirements of the standard apply.
8 m! h, m* i1 r& {8 [# b. V, m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。
% \* m3 y2 O! g. m" n欢迎拍砖
- w3 ~, ?. l1 i5 b# i5 v* [
2 Y& s# g& r: P$ l* g  [s:90] |
|关于安规|小黑屋|安规QQ群|Archiver|手机版|安规网
( 粤ICP13023453-10 ) 
窥视卡
雷达卡
发表于 2011-5-12 12:06
显身卡
楼主
