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请问如下这个测试怎么做啊& O% i) s2 ?0 }# }" e" K6 k5 d' L0 U
18 Limited Short-Circuit Test! _4 M2 m, x/ u
18.1 General
. g. C" o/ e" b/ K" S# ]+ X18.1.1 Following the test specified in 18.2.1 or 18.3.1, a thermistor shall:7 D% }; R8 p' I( n# o; u/ |
a) Comply with the requirements in 11.1.2 or be in a permanently high resistance state; and
( K& z$ ?6 ~& ~b) Complete the test without igniting the cotton indicator or opening the ground fuse described in
. T# D, ?2 G; S18.1.4 and 18.1.5.
+ r2 n. ?3 R5 H# |5 \1 ]18.1.2 When the results of the Limited Short-Circuit Test on the thermistor itself comply with 18.1.1, the6 n" \) t K$ @+ T- q, j I
test is not required to be repeated during the investigation of the end product.
, b/ F- Y5 H, y( u2 V18.1.3 Three samples of a control thermistor are to be subjected to this test. The test is to be conducted {0 G4 U0 a# ?
at rated voltage (Vr).! w) d* }! I* s+ z' K8 L$ F3 `
18.1.4 A ground fuse is to be connected between the metal enclosure, metal mounting surface, or metal
- ~" L! T2 A7 [( h cscreen described in 18.1.5 and the unswitched line to indicate an arc-over to the enclosure or mounting& V( T# F7 g3 R+ a; H5 W5 t) z
surface. Where each line is switched, the fuse is to be connected between the enclosure, mounting
$ w9 V; z( k% @* K" w. osurface, or screen and the live pole least likely to arc to ground. The fuse is to be a 3.0 A nontime-delay( }1 E; R+ M0 g' E5 s$ d. Y! l
fuse having a voltage rating not less than the rated voltage (Vr) of the thermistor.% t4 n2 _0 V' ]3 g6 w( H+ F1 x. L
18.1.5 Cotton not less than 12.7 mm (1/2 in) thick is to surround a metal screen enclosing the thermistor
3 l9 Z1 t# G5 d( ^at a distance not more than 12.7 mm from all parts of the thermistor.
+ T( K" C2 y! R. ~* m18.1.6 The cotton is to be surgical cotton, such as commonly used for medical purposes. |
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