66kV 1200mm2 XLPE Single Core twisted and compacted from the devastation of the Christchurch Earth Quakes

RANS Electrical has extensive knowledge and field experience in fault locating and high voltage cable testing along with the best high tech tools for the job.

Fault locating requires more than just a thumper or in some dangerous cases putting a bigger fuse or nails for fuses. Efficient fault locating that we offer requires the convergence of knowledge, methodology and the right hardware.

A total approach is needed to get the job done quickly to minimise customer outage time and damage to the cable system.

Our technicians have an extensive knowledge of the cable systems design, construction, and history, accurate maps, proper fault locating procedures, the right thumper, some cable burn down method, use of TDR/radar, a top level acoustical & electromagnetic listening device, radar detection and camera for visual inspection of faults.

When a client needs our help with locating a cable fault, time is usually a critical factor. One of our major Oil and Gas clients contacted us with a cable fault and, within 3 hours, we mobilised to assist. Unfortunately, after we had completed our diagnostics on the cables, we found two faults. One on the Red phase and the other on the Blue on the 780 metre 22kV Hybrid cable.

First fault
Using our specialised equipment, the first fault was located within 3 hours from signing onto the Electrical Permit. Due to the cable fault being in the middle of a fire access road, this prevented us from being able to excavate and repair the cable immediately. Once traffic management was in place we repaired the cable.

Second fault
The second fault was much more difficult to locate. The RANS team used a Time Domain Reflectometer (TDR) to locate both ends of the cable, as part of the diagnosis, but high impedance prevented them from pinpointing the exact location of the fault. The use of our equipment with the combination of a Capacitive Discharge System (CDS) and the Wheatstone Bridge method, we located the fault under a concrete service tunnel that had collapsed.

Outcome
We were able to locate and repair two faults that would have otherwise caused serious business interruption for our client. Despite the second fault being very difficult to locate, our expertise and equipment meant that we were able to isolate it and repair the cable.