Wow, I just realized that nearly half of my life has been spent either performing cable fault location or supporting others performing this task. Applications have varied from fiber optic, telecommunication, CATV, LAN and electrical power cabling. So as a little bit of an old timer in CFL I am absolutely amazed with how simple smart phone technology has made the training and support of this craft. Through the phenomena of camera phones and text messaging I can now guide technicians step-by-step through a CFL experience from the comfort of my climate controlled office!
Just a few weeks ago I had the opportunity to assist in a fault locate on a 35 kV, cross-linked polyethylene (XLEP) electric power cable on a wind farm. The cable was approximately 1,700 feet in length on the sectionalized span. VLF Hipot test results showed the cable breaking down at just less than 12 kV. Our client who had rented our Megger PFL40A Power Cable Fault Locating System had very little to no experience using the technique of Arc Reflection or cable radar methods. We assured him that this would not be problem and to simply call from the job site and we would be happy to guide him through the application.
Well our client took us up on our offer and now it was time to perform. Based on the test results obtained from the VLF Hipot, I was already expecting a very high impedance fault. Faults of this nature are typical of a splice failure or blow-out (open circuit) condition on the cable. With this knowledge I guided my client step-by-step through the equipment set up process. This part was straight forward since I was able to refer to exact controls on the PFL40A’s control panel.
PFL40A Control Panel
The difficulty came when it was time to interpret the cable radar pattern. Fortunately, here is where smart phone technology easily got us through the task. I had my client take a picture of the radar pattern and text it to my smart phone. Once I saw the picture it was obvious to me I was looking at a blow-out fault located at 1,018.3 feet into the cable under test. Next I wanted to see if the cable fault would arc over or “thump” since this would aid us in the final pinpointing stage. I then guided my client on how to initiate a breakdown surge and had him text me a new photo. The photo confirmed a flashing fault at the location of the blow-out. Now it was just a matter of sending a crew member to the measured location for confirmation. This took approximately 5 more “thumps.”
Radar Text Message
The total time spent on the locate was less than one hour and two text messages. Oh, and I guess I should confess … while my client was enduring 100 degree weather on the job site … I accomplished the support call from the comfort of Starbucks. Please don’t tell my boss!