A Cable Fault Locator Using Pulse Echo Measurement

Abstract

Increasing use of underground cables for power supply distribution has necessitated the need for quick and accurate fault location in cables at low cost. This paper describes a fault locator based on the principle of pulse reflection on transmission lines. The instrument has to be used alongwith an oscilloscope.

The equipment consists of a High Voltage Pulser, a variable-duration Sweep Generator and an Intensity Modulating Pulse Generator. The High Voltage Pulser generates negative pulses of nearly 1000 V amplitude. The Sweep Generator has been designed to give four time durations of 5, 20, 100 and 400 mus. The Intensity Modulating Pulse has two features. First, it ensures that the display on the screen of the oscilloscope is visible only for the time range selected. Second, it generates a bright spot on the display, the position of the spot in the time axis being adjustable by means of a ten-turn potentiometer. The accuracy of fault location is within ± 1 %.

Indexing Terms:

• Cable Fault Locator
• Pulse Echo Measurement