DSH 395 Separation of TNV-3 and SELV circuitry

小米

广东安规检测
有限公司提供：

小型摆管淋雨试验机

IPX5X6X7喷水试验机

1000L恒温恒湿箱

各种试验指现货

可程式恒温恒湿试验箱

水平垂直燃烧机

自动卷线器试验机

耐划痕试验机

各种灯头量规现货

灼热丝试验机现货

GB1002插头量规

IPX1-X7淋雨现货

IEC61347/UL935镇流器热试验箱

灯具防风罩

IK冲击试验机

UL498插头插座量规

VDE0620插头插座量规

稳定性试验台

家电温升测试角

针焰试验机现货

热电偶焊机现货

家电125mm试验指

E12灯头量规

无绳壶无绳电熨斗插拔寿命试验机

IEC60335试验指甲

DSH 395 * m+ i6 K  f5 X: r

Separation of TNV-3 and SELV circuitry 5 R* m( h  X& Y: k! e

2.3.2 3 U4 [' Y5 {" N* s8 |$ L

60950(ed.3) ' ?% j4 o# x% p: g8 S0 ^2 b

* t7 I: B8 l# X, o) ]$ W% MStandard(s):
IEC 60950 (1999) 3rd Ed.
! }3 q' f; K5 W; B; E& S, ~, A' DSub clause(s):
; s/ K" ]$ T: e' _3 G" T: J2.3.2
* H: E9 i$ x' T- g6 R; N) e7 NSheet No.
9 [. l% T) O5 n395
7 d% L% G) q' [5 hSubject:
Separation of TNV –3 and SELV
0 S9 g8 I* Q# }7 H5 l4 Ncircuitry
Key words:
- Separation of TNV-3 circuit
' J9 s5 j* S" O' K* nand SELV circuit
: b* ^# ?: b7 `2 M9 fDecision taken at the 39th
9 E# a6 s( ?1 V- ^' W5 qmeeting 2002
Question:
1. Is it permitted to demonstrate that a TNV -3 circuit is adequately separated from a SELV circuit by
$ s! Q8 G7 }6 @0 [' Kmeans of single fault testing, in the situation where the spacings do not meet the requirements for basic
- B, m1 t6 a, j" z. o8 f" \% Tinsulation? (The dielectric strength test is still required under Subclause 6.2.1.)
9 o1 `) c- V( M0 d) d0 N9 G2. If so, is it required under the compliance paragraph to short circuit the insulation between the TNVcircuit
and the SELV circuit at all points which do not meet the criteria for basic insulation, before
carrying out the tests?
6 q& h% {5 F5 C$ {; i3. If short circuiting the insulation before carrying out fault tests results in the equipment passing the tests,
+ ^, d1 w4 _5 G$ e* pwhereas carrying out the fault tests without short circuiting the insulation would result in the equipment
+ @: T. c/ n& H3 W0 |5 f7 Jfailing the test, should the insulation be short circuited?
! e  F* A! Q$ N" k4 wRationale:
1. Paragraph 1 of Sub-clause 2.3.2 requires that separation between a TNV-3 and a SELV circuit be such
7 }" w0 Q9 O+ F, i- F+ G7 d9 Rthat in the event of a single fault, the SELV circuit remains below TNV-3 limits. Paragraph 2 of Subclause
+ ]4 B/ C; ]$ D; D: Z* Q2.3.2 states that basic insulation will achieve this, but other solutions are not excluded.
Equipment is not required to meet either Paragraph 2 or 3. It can meet the single fault conditions stated
% @9 e/ i  e5 O7 l7 r& u: {in Paragraph one and in the compliance paragraph.
2. According to the compliance paragraph, before carrying out the single fault tests, insulation which does
not meet the requirements for basic insulation is short circuited. Presumably this does not mean that
short circuits are to be applied between all tracks and components in the entire TNV-3 and SELV
7 l# @; l9 i% n9 s1 Y+ z& [) jcircuitry which do not meet basic insulation, but that the insulation at the point where the TNV-3 circuit
) C8 n' ~- S- D+ r) Z8 _meets the SELV circuit is short-circuited.
" K5 C6 h# `1 y. m2 I' B' H4 J3. It is possible to envisage a situation where short circuiting the insulation between TNV-3 and SELV
; t# s7 W* c- N& U. M" Dcould cause the TNV-3 voltages to be lowered. Fault tests under this condition would not represent the
worst case possible fault condition
) y0 p' \% R7 Q- tDecision:
1. It is permitted to demonstrate compliance with Subclause 2.3.2 by means of single fault testing.
4 d; S4 b, n( _: V' _$ @2 D8 q. y$ DThe limits in 2.3.1.b) shall not be exceeded in normal or single fault conditions.
2. Before carrying out single fault testing of components and insulation, insulation between TNV-3 and
" c& E+ c5 V8 y3 w. h& @7 ISELV circuits not meeting the requirements of Basic insulation should be short circuited if this results in
a worst case voltage measurement at accessible parts of SELV and TNV-1 circuits, and at accessible
+ \6 G" f7 `9 ^' [1 K1 i( g7 B# Nconductive parts during subsequent fault testing.
3. If the single fault test would be more severe if carried out without short circuiting the insulation, the test
should be done without short circuiting the insulation.

% m: C. M4 y+ G/ p% I! I2 A4 u! B
1 W1 \; c+ X: t3 u