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高人指导下,同学习
$ L9 |1 \' T( n; H2.10.4.2 Material group and comparative tracking index' _& d F) B/ c/ j# V) g4 l
Material groups depend on the comparative tracking index (CTI) and are classified as follows:
' L$ @ R* A% ?; j# S& Y# k3 @4 c" n; fMaterial Group I CTI ³ 600
7 R0 i8 ^; i9 i5 rMaterial Group II 400 £ CTI < 600
5 y v! n: ?# D! E" i: A: W8 W2 oMaterial Group IIIa 175 £ CTI < 400: l' o9 M# _4 H# t5 n
Material Group IIIb 100 £ CTI < 175- A) F7 W O( i* G( T
The material group is verified by evaluation of the test data for the material according to IEC7 N5 N2 I( c- d( K" E0 \
60112 using 50 drops of solution A.; P4 h4 d6 s+ U$ T5 M1 K' O! p- s5 w+ j
If the material group is not known, Material Group IIIb shall be assumed.
- k* W/ P2 [& J6 ` i" vIf a CTI of 175 or greater is needed, and the data is not available, the material group can be% b- R4 q) V; z$ n
established with a test for proof tracking index (PTI) as detailed in IEC 60112. A material may& O0 l6 _0 o" |+ t
be included in a group if its PTI established by these tests is equal to, or greater than, the lower9 ^1 f6 E2 l& ?7 T# j
value of the CTI specified for the group.
L8 {" @9 D, q4 u: M% A& }6 K4 J( j4 @5 d
——UL60950-1-2007 |
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