Primary Cable Fault Locating - Instant Video
This 24-minute video describes common types of primary cable faults, their characteristics, and how to test for each one. It covers equipment commonly used for fault testing, a seven-step method for finding faults, and safe procedures to follow when locating primary cable faults.
Introduction – 4 minutes
Describes and illustrates the characteristics of four types of faults: Low resistance faults, high resistance faults, dead shorts (shunt faults), and open faults.
Equipment – 6 minutes
This section covers nine pieces of equipment used to locate faults: Fault indicators, hi-pot adapters, megohmmeters, time domain reflectometers (TDRs), DC hipots, thumpers, burners, impulse detectors, and cable locators.
Seven-Step Method – 5 minutes
How to troubleshoot a faulted cable situation, determine the characteristics of the faulted cable, de-energize the cable, and analyze the fault.
Prelocation – 4 minutes
It’s important to avoid excessive thumping of cables. How to set up a TDR and use it to determine the distance to, and the nature of, low resistance, open, and dead-short faults.
Arc Reflection – 5 minutes
High resistance faults can be difficult to locate. Sometimes it is easier to “burn” the fault until it is a low resistance fault. This is not always an ideal approach. The video offers the arc reflection method as an alternative. Using a thumper and a TDR in combination, the distance to the low resistance fault can be determined. As a final step, the fault is pinpointed by walking the path of the cable and hearing the thumper by ear or with a sensitive listening device.