Finding the location of an underground cable fault doesn't have to be like finding a needle in a haystack. GSCST uses many different locating methods, coupled with new detection technologies, that make this task much easier and less time consuming. However, there is no single method or combination of methods that is "best." Our selection of the appropriate method for the situation and our skill in employing that method are the keys to safely and efficiently locating cable faults without futher damaging the cable. Ask us about our Power Generator Rentals if getting power back immediately is a concern!
Basic cable fault locating methods:
There are three basic methods of locating an underground cable fault.
Sectionalizing: This procedure risks reducing cable reliability, because it depends on physically cutting and splicing the cable. Dividing the cable into successively smaller sections will enable you to narrow down the search for a fault. Referred to as "divide and conquer" this procedure is repeated until reaching a short enough section of cable to allow repair of the fault. This laborious procedure normally involves repeated cable excavation along the length of the cable.
Thumping: We supply a high voltage current to a faulted cable, the resulting high-current arc makes a noise loud enough for our technicians to hear above ground. While this method eliminates the sectionalizing method's cutting and splicing, it has its own drawback. Thumping requires a current on the order of tens of thousands of amps at voltages as high as 25kV to make an underground noise loud enough to hear above ground. The heating from this high current can possibly cause some degradation of the cable insulation. We are highly proficient in the thumping method, and can limit damage by reducing the power sent through the cable to the minimum amount required to conduct the test. While moderate testing may produce no noticeable effects, sustained or frequent testing can cause the cable insulation to degrade to an unacceptable condition requiring a complete replacement. There is no existing technology (or combination of technologies) that can entirely replace thumping.
Earth Gradient Fault Detection: Commonly referred to as "Pinpointing" it is designed to pinpoint nicks or cuts in secondary voltage underground cables or wires where voltage is leaking to ground. The transmitting unit sends a powerful pulsed charge that is detected by the receiver. Our equipment is able to detect large and small cable faults which will aid in your decision to repair or replace the cable.
Direct Bury Cable Fault Repair