Location of Fraudulent Branch Lines or Faults in Short-Length Low Voltage Lines

Abstract

The detection of irregularities such as a fraudulent branch line or a fault in short-length low voltage (LV) lines is of great interest for electricity supply companies as well as for other businesses. This paper describes and systematizes new techniques that afford in-depth knowledge of the occurrence of irregularities in these lines for the first time. Firstly, it has been characterized the response of a typical short-length tapped line by means of conventional time-domain reflectometry (TDR) technique as well as the additional new techniques proposed. These techniques are based on a conventional mathematical treatment of discrete-time signals. Moreover, they obviate the need for visual inspection at remote locations and only involve a moderate computational effort. Finally, it is exposed how fraudulent branch lines were detected in two real domestic supplies at the local electricity supply company by the proposed techniques. The first fraudulent line was detected in a long incoming main line buried in the ground by mean of the line-symmetry technique. The second one was detected in a short incoming main line located in building voids by the second echo and power spectral density methods. The accuracy of the results has been assessed in laboratory tests as well.

Keywords

• fault location
• time domain reflectometry
• traveling wave devices
• correlation
• discrete Fourier transforms