时域反射电缆测长中的波速特性

宋建辉, 袁峰, 丁振良

哈尔滨工业大学电气工程及自动化学院



摘要:

行波波速是决定时域反射电缆测长系统测量精度的关键.为了减小波速的影响,研究了时域反射电缆测长中的波速特性,分析了行波传播速度和介电常数的频率特性,研究了电缆的材料特性和环境温度对电缆中行波传播速度的影响,总结了确定波速的依据.实验测量了行波信号在不同温度下的波速,给出了行波在PVC绝缘电缆中传播速度的温度补偿系数.实验结果表明,经过波速温度补偿后,时域反射电缆测长系统的测量精度得到显著提高.

关键词:  时域反射  电缆  波速  频率特性  温度补偿

DOI：10.11918/j.issn.0367-6234.2011.04.012

分类号:TM930.12

基金项目:



Velocity characteristics of time domain reflectometry cable length measurement system

SONG Jian-hui, YUAN Feng, DING Zhen-liang

School of Electrical Engineering and Automation,Harbin Institute of Technology,150001 Harbin,China

Abstract:

Traveling wave velocity is the key to the measuring accuracy of the time-domain reflectometry cable length measurement system.To reduce the impact of velocity,the velocity characteristics of time domain reflectometry cable length measurement system are studied,the frequency characteristics of traveling wave propagation velocity and dielectric constant are analyzed,and the influence of cable material parameters and ambient temperature on traveling wave propagation velocity on cable is investigated.The basis for determining the wave velocity is summed up.The signal propagation velocity at different temperature is measured,and the temperature compensation coefficient of traveling wave propagation velocity in the PVC insulated cable is presented.Experimental results show that the measuring accuracy of the time-domain reflectometry cable length measurement system is improved significantly by velocity temperature compensation.

Key words:  time-domain reflectometry  propagation velocity  frequency characteristic  temperature compensation