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UL黄卡中RTI 含义
! H1 X1 N: h. o8 uRTI的出处在UL746C中，相关章节： Relative Thermal Index 37.1 The relative thermal index of a material is to be based upon an evaluation of long-term thermal-aging data obtained under a program described in the Standard for Polymeric Materials – Long Term Property Evaluations, UL 746B.
7 e. N* C) q: [1 d% c37.2 Essentially, the Standard for Polymeric Materials – Long Term Property Evaluations, UL 746B, procedure allows the thermal-aging characteristics of a material to be determined by measuring the changes in its properties to a predetermined level by aging at each of several elevated temperatures, plotting the logarithm of time at each temperature against the reciprocal of absolute temperature using the best-fit straight line by the least squares method of regression analysis. The time-temperature relationship may be expressed as:8 V4 j. ?7 D' ` O6 @% y& R
Ln(t) = A + B/T C$ s p9 I( r. N
in which:
( a3 _! z7 c( }6 g/ ~. f9 z, pA is Constant (frequency factor)& T X; O; q! c( s; C- u! f
B is Activation (Energy Constant)
! G9 O( ]3 a/ e/ k7 O( v; MT is Absolute temperature, °K (°C + 273.16) and, ], y+ A0 `: e& Z' P" T; l
In is Natural logarithm
+ W7 W$ g# X* K# Z. f37.3 A comparison of the thermal aging characteristics of the candidate material against those of a
9 u# k# Z1 n4 Cconcurrently tested control material having proven field service, provides a means for estimating a relative thermal index level where the candidate material is expected to have an acceptable field service history.$ X8 M/ S, S3 V0 n/ E2 r' `2 o
For each material, a number of relative thermal indices can be established, each index being related to a specific property, color, and thickness of the material.0 z4 D$ \% F+ m7 ~0 R7 S2 a$ x
37.4 A polymeric material having a use operating temperature higher than the applicable relative thermal index, shall be considered acceptable if it complies with the requirements for Functional Use Temperature Indices (Section 35) or Relative Thermal Capability (Section 38). 简单介绍一下：
0 ~+ q9 |# _8 ]+ ZRTI，相对保证温度，是UL保证材料使用的最高温度。单位为℃。有时也只标注为TI（保证温度）。里面有三个指标， Elec：Electrical，7 g) b4 g5 V9 d0 C* d! Q" {
IMP：Impact，: ?3 {' O/ q% e
Str：Stress， Elec表示对于电气特性的TI ；imp表示有冲击负荷时的TI；str表示静态下的TI。 一般都使用第一个。 |
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发表于 2009-2-9 10:30
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