Abstract—To against the problem of the difficult for indentifying the reflected wave of traveling wave and the need of plentiful practical experience and operation skills, this article focuses on designing and developing a digital cable insulation automatic fault locator. The instruments which can locate the fault without the data of length of the cable is based on the principle of HV bridge method and consist of bridge use for measuring cable length and bridge use for locating cable insulation fault. It can automatically improve voltage output of the high-voltage power through constant current detection circuit. To make sure the abilities of high accuracy,stability and fast for this instrument, This article introduces high-precision digital potentiometer, optical isolation and self-balancing bridge.The optical isolation between high and low pressure not only can achieve a complete electrical isolation,but also improve the  anti-interference for the system.

Index Terms—self-balancing bridge, digital potentiometer, optical isolation

Cite: Wu Zhu, Hua-Fu Zhang, Wei-Ya Ma, and Yuan Gui , "Study on the Automatic Positioning for Cable Insulation Failure Based on Digital Bridge Method ," Journal of Automation and Control Engineering ,  ,, Vol.1, No.1,   pp. 7-10,  March 2013. doi: 10.12720/joace.1.1.7-10