- U0 p" Y, h) _3 ?8 x , q/ }4 N( t& s* a/ W# t. g: j; K$ aThe voltage source of a dc or ac spark tester shall maintain the following test voltage under all nor 7 y# k% d) U! C* g6 M 7 R0 {2 l( S5 o& j7 b6 A3 ymal conditions of leakage current: : L1 j3 K* j/ | d5 ]1 b, K) E% Qa) An essentially sinusoidal rms potential of 1750 V for an ac test; 6 j, A8 p- b: M, d- P# \4 f ?
7 ]% x: |8 G# ib) 2500 V for a dc test. The current output of which the dc power supply is capable shall not exceed8 s( e; m; w; L
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5 mA. Any ripple shall not exceed 1 per cent. After a fault, the dc test voltage shall recover to the full $ w. T$ M$ v; e9 s1 k) H
( F( P7 t) p! ?. {test voltage in 5 ms or less, unless 610 mm (2 ft) or less of the product travels through the electrode 3 h5 [( _+ m5 R) y7 w: Qe in the time that it takes for the full voltage recovery; r) O, e* n4 }' u! ]
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c) For conductor gauge sizes 22 – 30 AWG which are to be used in cables without coaxial membe, ]6 n+ p# ^+ M
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rs but with foam or foam skin insulation and protected by bonded metal shields, the following spar " P" G! L" G5 F: W ) r0 q4 ~* d$ Dk test voltage may be used: " L- i. C; j+ Y. W# [: U$ O
Conductor size Test Voltage , r- W7 G+ Q5 i9 w! }0 [ 22, 23 AWG 1500 V dc or 1050 V ac 2 T- k; I1 a" |& X5 }
24, 25 AWG 1200 V dc or 850 V ac ! a9 l6 [: @0 B* U% t 26–30AWG 1000Vdcor750Vac 1 q/ B! j" H! d 6 e8 P, o# U; a c7 \9 _: vd) For cables without bonded metal shields, and with foam insulation that is not more than 0.20 m' Q( ~/ ]% z$ v/ R/ ^
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m (0.008 in) in average thickness and does not have a skin, the spark test voltage may be reduced3 |: v7 C) d# }" a: a, G
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to 1250 V ac or 1750 V dc, provided that the dielectric strength test voltage required by Clause . Y; j! s! T _$ e
1 O/ p7 S9 k. ]8 M5 W7 B9 ]. q5.3.5 is met. # W x9 o0 p1 }# |2 f. R $ `+ k# e* p9 d: T这段内容看得有点糊涂，前辈们可否指导一下？* d! i* z |. ^. {+ q# Y d
问题1. 首先我不理解d)中所涉及的skin在实物中是什么？ - {% K% ?" n( v, t5 b( Y, Q问题2. c）中foam 和foam skin 有何区别？ 4 `# Y: b/ r. M1 o我想先把这个问题搞清楚了作者: stevenyu 时间: 2009-9-30 11:36
d中所指的skin是外皮層,針對發泡絕緣的結構,& O" ^% f* ^6 H
根據不同發泡形式,可能會有：! A" \$ f- l0 a3 |* Q
a.發泡層, 所謂的foam, 9 J4 \. H" }6 W9 _7 Fb發泡層+外皮層(實心), 所謂的foam skin. 5 G- i" b; w5 U. u8 _7 A
c內皮層(實心)+發泡層, 所謂的skin foam. 5 t0 q5 M: G2 L) @
d.內皮層(實心)+發泡層+外皮層(實心), 所謂的skin foam skin.% a# |' Z% }, J- N# C& l
所以foam與foam skin就差在有沒有外皮層. R5 R9 @* _$ H/ B, N+ O' e: J======================================= . B2 _7 N) J, q: I * r+ L, d4 \- S) Q帮兄弟修改下，便于理解。0 J$ |5 u A. |2 N+ ^
呵呵。
