KEP Power Testing Blog: Cable Fault Pinpointers: Choosing the Right Instrument

Cable fault location cannot be imagined without the actual pinpointing of a cable fault, which can be challenging and time-consuming. How soon the result is delivered heavily depends on the pinpointer being used; yet, there still appears to be some confusion as to how to choose the right one. This article will highlight the differences between the principal pinpointer types, and, hopefully, will equip the users with the information needed to make the right choice.

Pinpointers with an acoustic sensor

Description: a basic type of pinpointers, which can be effectively used for fault pinpointing on short cable lengths provided the line route is known.

Advantage: low price.

Limitation: in most cases purely acoustic pinpointers are inefficient when it comes to locating a fault on unknown cable routes and/or longer cables as they cannot trace the cable route and measure the distance to the fault.

Pinpointers with an electromagnetic sensor

Description: an alternative to acoustic pinpointers, designed to pick the electromagnetic signal of the discharge.

Advantage: low price.

Limitation: also limited in applications since purely electromagnetic pinpointers are unable to measure the time delay between acoustic and electromagnetic signals, based on which the distance to the fault is identified.

Dual-signal pinpointers integrating one magnetic sensor

Description: fault pinpointing instruments equipped both with an acoustic and a magnetic sensor, making it possible to pick the two types of signal and calculate the respective time delay.

Advantage: the flexibility of switching between the acoustic and inductive fault locating methods makes such a pinpointer suitable for various testing conditions; can measure the time delay between acoustic and electromagnetic signals; significantly lower priced compared to the following type.

Limitation: cannot show the direction to the fault.

Dual-signal pinpointers integrating two magnetic sensors

Thus, out of the four described options, the latter two enable most accurate fault location in as little time as possible and, therefore, lower cable maintenance costs. The choice between them should be made based on your circumstances: the one with two inductive sensors will make the process faster, but at quite a high cost, whereas the reasonably-priced pinpointer with a single inductive sensor with an acoustic one is just as effective, being perfect value for money.

Dual-signal pinpointer incorporating an acoustic and electromagnetic sensor P-900

Pinpointer P-900 is designed to:

Locate underground cable lines and power cables;
Measure cable depth;
Pinpoint shorts;
Pinpoint insulation faults.

P-900 should be used with an auxiliary frequency generator of 1024 ± 2 Hz / 2048 ± 2 Hz and no less than 200 W of output power at the load range from 0.5 to 200 Ohms (e.g., LFG-2500) when searching using the inductive method.