Not for high voltage, but for fire alarm cabling on utility poles.
I had a Riser Bond TDR that I used for fault location.? A long time ago I was asked to find a fault in a municipal cable that was once used for fire alarm call boxes.? The fault was an open circuit.? One of the things that you have to take into consideration is the velocity factor of the cable that you are troubleshooting.? This is usually impossible to know.? So I used another method.? I measured the fault from either end.? Just for a theoretical example, the TDR measurements were 1000 feet and 500 feet.? The actual physical length of the cable was 1000 feet. Interpolating that, the fault was 666 feet from one end and 333 feet from the other.? Sure enough, we found the cable had visible physical damage at this distance and fixed the problem.
I've never done underground TDR testing, but the same method should apply.? If it is a single hard fault (open, short) you should be able to find it.? Multiple faults could be very hard to find.? Be careful of any stray voltage on the cable, as it can damage the test equipment.? We had an Hewlett-Packard TDR test set that was damaged by voltage on the cable.
Joe, K1ike
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On 4/7/2025 11:38 PM, Karl Shoemaker via groups.io wrote:
Anyone have experience using a TDR to locate an underground fault for high voltage ?
