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高人指导下,同学习
8 F% M& ` ]$ n2.10.4.2 Material group and comparative tracking index
+ u b* d! }! y& C \Material groups depend on the comparative tracking index (CTI) and are classified as follows:7 M; r' C9 |0 d; m2 Z: f' j; r, R! ~* }
Material Group I CTI ³ 600) U0 B# E& h% \/ Y; @# w* s
Material Group II 400 £ CTI < 600
1 \' N- H+ ~" o$ i& a0 Q5 ?: SMaterial Group IIIa 175 £ CTI < 400
" m& p. M3 \+ J4 vMaterial Group IIIb 100 £ CTI < 175
% b+ o( K# z' M/ n' jThe material group is verified by evaluation of the test data for the material according to IEC
4 f4 t; f; ]3 g9 [60112 using 50 drops of solution A.
* b2 s7 \) y( B2 y3 }If the material group is not known, Material Group IIIb shall be assumed.2 z2 ]8 a9 ]! j8 ?/ `( Z, T+ [
If a CTI of 175 or greater is needed, and the data is not available, the material group can be6 T @& s* c* u0 q7 S# }8 \& {
established with a test for proof tracking index (PTI) as detailed in IEC 60112. A material may5 V" l4 Z6 ]3 [$ U3 n4 d& y
be included in a group if its PTI established by these tests is equal to, or greater than, the lower0 t, S4 \ D: d& B- l, s
value of the CTI specified for the group.
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, l$ c* e& D' w" D7 x——UL60950-1-2007 |
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