|
高人指导下,同学习6 K3 Q5 r/ o+ A$ Y
2.10.4.2 Material group and comparative tracking index: w: S" Z6 D+ f0 o6 c U0 W
Material groups depend on the comparative tracking index (CTI) and are classified as follows:- Y u/ m( j8 ~5 x c
Material Group I CTI ³ 6004 ^1 w/ e5 I4 q3 l# s6 E" m4 n
Material Group II 400 £ CTI < 600
0 n# U& `' z b/ L! ?4 C- VMaterial Group IIIa 175 £ CTI < 400
; e! L: E8 C; DMaterial Group IIIb 100 £ CTI < 175) O6 _- y6 v* E7 a& y, L1 s
The material group is verified by evaluation of the test data for the material according to IEC, |+ c- [0 ~" m0 i1 o
60112 using 50 drops of solution A. U; D5 t/ U8 P2 Q" W
If the material group is not known, Material Group IIIb shall be assumed.
0 ?$ k9 S! F3 e2 AIf a CTI of 175 or greater is needed, and the data is not available, the material group can be. f. l, u1 S! D& o: V5 m) m* E7 K/ R
established with a test for proof tracking index (PTI) as detailed in IEC 60112. A material may X+ I4 J8 a$ {$ g' E9 S) S: x
be included in a group if its PTI established by these tests is equal to, or greater than, the lower
! c( C$ J% x! r- M# ?% N ?value of the CTI specified for the group.
* }$ m t. q# f4 m& r _5 F+ h
: Z, X6 y, z) d1 r8 Q6 |——UL60950-1-2007 |
|