截面积测试方式对电缆用薄铜带ρv测试值的影响

Influence of Sectional Area Test Method on Volume Resistivity Test Value of Thin Copper Strip for Cables

电缆用铜带体积电阻率ρ的精确测定是确保电缆使用性能的关键。由于标准GB/T 3048.2-2007对试样截面积测试方式的指导性仅为定性,导致各实验室对一些特殊情况(如铜带厚度≤0.09 mm)试样截面积测试时选择了不同的测试方式。针对电缆用薄铜带ρ测试值受所选择的试样截面积测试方式影响较大的现象,以0.08 mm(厚)×150 mm(宽) T2O60铜带为试样展开了试验研究。研究结果表明,相对于称重法,测量法(计算法)测得的试样截面积具有更高的精确度,进而由此可获得精确度更高的电缆用薄铜带ρ测试值。对测量法测试截面积时电缆用薄铜带ρ测量不确定度进行了评定,对于0.08 mm×150 mm T2O60电缆用薄铜带,其测得的ρ相对扩展不确定度U=3.4%。

The accurate measurement of volume resistivity ρof copper strip for cables is the key to ensure the service performance of cables. Since the guidance of GB/T 3048.2—2007 on the test method of sample sectional area is only qualitative, each laboratory selects different test methods for the test of sample sectional area under some special circumstances(such as copper strip thickness ≤0.09 mm). In view of the phenomenon that the ρtest value of thin copper strip for cables is greatly affected by the selected sectional area test method, an experimental study is carried out with 0.08 mm(thick)×150 mm(width) T2 O60 copper strip as a sample. The results show that the sample sectional area measured by the measurement method(calculation method) has higher accuracy than that by the weighing method, and then the ρtest value of thin copper strip for cables with higher accuracy can be obtained. The uncertainty of ρmeasurement of thin copper strip for cables when measuring sectional area by measurement method is evaluated. For 0.08 mm×150 mm T2 O60 thin copper strip for cables, the relative expanded uncertainty Uof ρmeasured by this method is 3.4%.