参考PAG clause 2.10.2-3 Working voltages in TNV circuits
5 ]% d2 J& s4 A( tIf the equipment generates a ringing signal and the circuit connects to a Telecommunication
) j t! ?# M5 ANetwork, the working voltage should be measured in accordance with sub-clause 2.10.4 and
% W2 _( d- r$ z9 J, eAnnex M.3.1 to determine maximum peak, rms and/or dc values.
, S4 k' J4 i t0 h% V. V, gIf the equipment is intended for connection to a U.S./Canadian Telecommunication Network and
# b9 D) w |, R" A ereceives incoming analog telecommunication signals (e.g., from a Central Office), the following
! L5 a; [: G" y% P7 x) imaximum working voltages (TNV-3) should be assumed for purposes of determining required4 s+ H2 ^+ }% l# X
clearances, creepage distances and electric strength test values:
" C$ R; ^1 Y" V" ka. peak: 200 V
2 V/ q) Z( N. Sb. rms: 120 V1 B4 W6 z& I9 ?5 R5 P
c. d.c.: 60 V$ v6 d9 ]$ }- m) u: U1 b
176 PAG 60950-1 JULY 15, 2008
6 i7 v5 Y9 A- c5 |If the equipment is intended for connection to a European Telecommunication Network, consult5 d4 e+ \* V. ]+ _4 e, A* P
with IEC TR 62102, Technical Report on Electrical Safety Classification of interfaces for& i: E1 |* }9 k
equipment to be connected to information and communications technology networks.
; T* W; Q; {3 w" Z7 mThe peak and rms values are used for clearance and electric strength determinations, and the
. @! f9 D. k+ e8 G: ^# c" g! Pd.c. value is used for creepage distance.
5 v( y% c4 a: b( L% N& jRATIONALE:! P1 @# q- R8 y3 U( E
Annex M (normative) describes maximum voltage levels associated with Telecommunication
7 k' o6 }, r6 M! D; r. LSignals that comply with FCC Part 68. The maximum peak value specified is 200 V referenced
9 H4 y. _& I% r& D$ M/ wto earth. Since working voltages typically are measured to earth, this value should be considered" Q( y( O! |: I5 _" J
the maximum peak value in the U.S. and Canada.
7 B! u, ~& o8 H* aAlthough Annex M does not contain a corresponding rms value, 120 V rms is an approximation6 X+ q+ @& h; a5 k# |7 j( l
of a composite 56.5 V dc and 300 Vp-p signal. Sub-clause 2.3.5 uses 120 V rms to simulate8 m5 ]1 e' M9 X+ p( r, z! q$ E& c
externally generated operating voltages. Therefore this value should be used for investigation to
8 Y5 v5 [) u! `/ ~* Dthis Standard. Also, sub-clause 2.10.4 indicates that cadenced ringing signals in TNV circuits
) v; \' F! t. d4 Sshall not be taken into account for determining creepage distances, thus a 60 Vd.c. value may2 O( V9 @" a+ ^ m! S+ p
be used.
6 l b( \+ s5 S9 i根据class III equipment定义的条款$ I% I5 {; a4 w$ M5 D
1.2.4.3 CLASS III EQUIPMENT: equipment in which protection against electric shock relies upon
( @7 r5 b; j7 \supply from SELV CIRCUITS and in which HAZARDOUS VOLTAGES are not generated
/ _% f9 m# h+ wNOTE For CLASS III EQUIPMENT, although there is no requirement for protection against electric shock, all other requirements of the standard apply.
/ P6 B; H2 z* a" G! {, ]* R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。
9 c. s: N2 _6 d! I8 q0 N欢迎拍砖& G9 B/ I) Z5 f; p B! L2 f
: u, @" c9 ]! }. I" x2 W! h
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