参考PAG clause 2.10.2-3 Working voltages in TNV circuits4 W7 D1 {! @" G& h! |
If the equipment generates a ringing signal and the circuit connects to a Telecommunication! D% t5 I- D, g1 W
Network, the working voltage should be measured in accordance with sub-clause 2.10.4 and
& s, ?% J0 k, j4 x6 XAnnex M.3.1 to determine maximum peak, rms and/or dc values.) O) M/ i) s0 H0 v; G
If the equipment is intended for connection to a U.S./Canadian Telecommunication Network and/ O! C* `9 _9 i) K9 i2 `
receives incoming analog telecommunication signals (e.g., from a Central Office), the following
5 `7 q+ b% Z9 }9 K1 Z$ zmaximum working voltages (TNV-3) should be assumed for purposes of determining required
+ E" u8 n" o8 I2 \+ ~7 ]! Fclearances, creepage distances and electric strength test values:$ M$ l- n g: w( l; K
a. peak: 200 V
, T, f, z: W* \- Db. rms: 120 V+ q2 L( A' R" [ B2 B% q" o4 P# |
c. d.c.: 60 V. c3 e7 ^; J+ V' l1 t
176 PAG 60950-1 JULY 15, 20088 a) k. r" L1 D4 a0 u& J8 ^; Q
If the equipment is intended for connection to a European Telecommunication Network, consult
9 V8 ?! V, u; U4 r, dwith IEC TR 62102, Technical Report on Electrical Safety Classification of interfaces for
5 C: z& C: r" B, c Hequipment to be connected to information and communications technology networks.. Y- e: N4 J6 `) M& E, \. b% t
The peak and rms values are used for clearance and electric strength determinations, and the
$ _1 T r- n- ^+ z4 vd.c. value is used for creepage distance.
; s8 H5 d0 g- k; S# x9 n/ jRATIONALE: o! {- c, _" v" p4 {! ]" ^, Q
Annex M (normative) describes maximum voltage levels associated with Telecommunication
6 B# N9 W4 E7 e( TSignals that comply with FCC Part 68. The maximum peak value specified is 200 V referenced
( r- C- b( e' ^2 [( A8 Fto earth. Since working voltages typically are measured to earth, this value should be considered1 j: g- E1 w5 A" Y
the maximum peak value in the U.S. and Canada.
$ N0 d+ q* u/ E; _# N) CAlthough Annex M does not contain a corresponding rms value, 120 V rms is an approximation- ?, z% p5 ?. \6 V
of a composite 56.5 V dc and 300 Vp-p signal. Sub-clause 2.3.5 uses 120 V rms to simulate# Z( R* O7 S, X( }; r
externally generated operating voltages. Therefore this value should be used for investigation to
: _& ^2 E, C7 m1 Sthis Standard. Also, sub-clause 2.10.4 indicates that cadenced ringing signals in TNV circuits
) F/ _1 l! O6 G p1 H6 ushall not be taken into account for determining creepage distances, thus a 60 Vd.c. value may5 l4 C$ R6 s" \7 A7 q; V0 \
be used.
" @* b, J' j* o8 ?! ?' h7 C0 X( k5 [3 s根据class III equipment定义的条款+ `* s0 A% ]7 V6 D/ @
1.2.4.3 CLASS III EQUIPMENT: equipment in which protection against electric shock relies upon% w! t3 X' R& i# f8 A
supply from SELV CIRCUITS and in which HAZARDOUS VOLTAGES are not generated4 A* [" w2 e4 S3 t
NOTE For CLASS III EQUIPMENT, although there is no requirement for protection against electric shock, all other requirements of the standard apply.
' A0 ?! h4 S1 g$ t! t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。
; a9 H' j- _1 W: X欢迎拍砖3 B% J" v. M4 u/ M3 t
9 s7 C/ k" y9 f3 J7 }  [s:90] |
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