灯具低压电路是否可以用28AWG线

themaster

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      有一款LED灯具，隔离电源低压电路中用28AWG（105C，VW-1 300V 有UL认证，绝缘层厚9mils 约0.23mm，导线正常承载电流0.32A，最大0.36A），两端带连接座，是连接控制电源版和PIR感应器电路板的，电流远小于2A。标准上没说不可以用，但有对电线横截面积小于0.4mm2的有限制，即要考虑正常工作条件下的最大电流和故障条件下的流过的电流强度和时间，以避免任何条件下的绝缘层过热。
( Q( \7 Y- u8 @5 ?. ]" F" c    本人以前没接触过灯具，请教一下，怎么判定该线是否可用（只从安规角度）？需要做什么实验？
$ g. O) t# L4 S# G6 L$ G5 r

themaster

自顶一下。请熟悉灯具的工程师大神们指点一下。

qij1979

参考IEC 60598-1:2014/AMD1:2017，5.4条款

themaster

qij1979 发表于 2018-4-8 08:53
' t$ {/ G+ j# ^' J6 R" ^% S参考IEC 60598-1:2014/AMD1:2017，5.4条款

( w9 ^$ C" F3 A, o谢谢你的解答。可我手头上的IEC60958-1：2014（非正式版）没有5.4章（直到5.3章），你能传一下这个60598-1:2014/AMD1:2017，5.4分享一下吗？

Nezof

5.3.1.2 For wiring which is connected to the fixed wiring via an internal current-limiting device
and limiting the current to 2 A maximum, e.g. lamp current control device, circuit cut-outs,
' o, \  v3 N$ u/ O+ I6 Q; Hfuses, protective impedance or isolating transformers, the following is applicable:
-the minimum cross-sectional area which may be less than 0,4 mm2 shall be selected in
relation to the maximum current during normal operating conditions and the time and level
# G8 g( r$ T+ l6 Yof the current flowing during failure conditions, owing to the fact that overheating of the wire
insulation shall be prevented under any condition;
$ i  ]. D  ~2 e; ^! i' N– the minimum insulation thickness, which may be less than 0,5 mm (PVC or rubber), shall be
- t9 B: u; T% ]- O4 cselected in relation to the voltage stress occurring.

qij1979

4 `0 u4 G. c( Y

themaster 发表于 2018-4-8 14:39
谢谢你的解答。可我手头上的IEC60958-1：2014（非正式版）没有5.4章（直到5.3章），你能传一下这个60598- ...

9 r$ |1 W$ v8 R: ^7 ]5.3.1.2
Replace the first dashed list item with the following new text:
9 [3 Z1 M4 Q, l% }7 k– the minimum cross-sectional area may be less than 0,4 mm2  if overheating of the wire
conductor insulation is prevented under normal and short circuit operating conditions in
accordance with the tests of 5.4;
* h' M" q8 z' cAdd, at the end of 5.3.7, the following new Clause 5.4:
5.4 Test to determine suitability of conductors having a reduced cross-sectional area
To determine suitability of conductors having a reduced cross-sectional area, connected to
) D+ @7 f2 ^0 ?( t) Dcontrolgear that limits the current to 2 A, the following test shall be conducted:
  R! U0 j  Z8 b' X  C6 C/ G* @2 `4 Za) disconnect the conductors being evaluated as close as practical to the lights source in the
luminaire and attach a resistive load using minimum 1 mm2  cross section test leads; these
leads shall be routed out of the luminaire in a manner that will have the least impact on
! p, ~& N0 n+ c5 A# A* J* }  itemperatures within the luminaire;
b) adjust the resistive load to measure the maximum output current of the control gear,
, W  t! w: W9 Q( R% \' ~maximum measured current shall not exceed 2,5 A;
c) with the resistive load set to draw maximum output current, conduct the thermal test in
accordance with 12.4. (see Figure 33);
d) the resistive load is then set to 0 Ω (short circuit) and the thermal test repeated in
accordance with 12.4 (see Figure 33);
In no case shall the temperature of the luminaire wiring insulation exceed the limits stated in
Table 12.2 nor shall there be any indication of damage to luminaire wiring.

themaster

Nezof 发表于 2018-4-8 14:56
2 D; L+ H4 C( B  K5.3.1.2 For wiring which is connected to the fixed wiring via an internal current-limiting device
a ...

谢谢你的解答。28AWG线横截面积大约0.32mm2，应该小于0.4mm2的限值，但该产品在这个连接线上的电流非常小，小到几乎可以忽略，所以正常工作状态下的电流和故障状态下的电流和时间累计，也小到可以忽略。关于最小绝缘厚度，这个线只有平均9mils，肯定没有0.5mm的，并且该绝缘材料只能承受300V电压，不过这个回路的电压是12V左右，即便在短路或其他故障状态下貌似这里也不可能有电压高于12V的情况，这个应该判定没问题吧。不知道上述看法是否需要试验和测试做佐证。

themaster

qij1979 发表于 2018-4-8 15:14
5.3.1.2
, M  C) H/ S- lReplace the first dashed list item with the following new text:
– the minimum cross-se ...

谢谢。过5.4测试应该没问题。

themaster

qij1979 发表于 2018-4-8 15:14
5.3.1.2
Replace the first dashed list item with the following new text:
– the minimum cross-se ...

你这个标准能否共享一下啊？多谢

qij1979

themaster 发表于 2018-4-8 16:17
你这个标准能否共享一下啊？多谢

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