When at some local point in a cable, insulation has deteriorated to a degree that a breakdown occurs allowing a surge of current to ground, the cable is referred to as a faulted cable and the position of maximum leakage may be considered a catastrophic insulation failure. After all clearances haven been obtained and the cable has been isolated in preparation for cable fault locating, it is strongly recommended that a fixed plan of attack be followed for locating the fault. As in diagnosing any complex problem, following a set step-by-step procedure will help in arriving at the solution or, in this case, pinpointing the fault efficiently. At the very start, it is a good idea to gather as much information as possible about the cable under test. Information that will help in the fault locating process is:
. Cable type-is is lead covered, concentric neutral (bare or jacketed), tape shield?
. Insulation type- is it XLPE, EPR, Paper?
. Conductor and size – is it CU, AL, standard, solid, 2/0, 350MCM?
. Length of the run – how long is it?
. Splices – are there splices, are the locations known?
. T-taps or wye splices – are there any taps, are the locations known, how long are branches?
Fault location on communication and power cables is a very specialized area of electrical technology. The performance of efficient fault location is very much dependant on good logistics and knowledge. Fast and reliable fault location is dependent on these factors if prelocation of a fault is to be done with high accuracy.
Cable testing, cable diagnosis and partial discharge measurements, will become of higher importance in the future. The condition based preventive maintenance of cable networks, will more and more replace the event oriented maintenance of cable installations.
A good detailed knowledge of the construction of cable networks, cable types and their accessories, simplifies the evaluation of the measured results considerably. Many of these are processes are the essential grounds for correct decisions to be made. The types of cable faults and required steps to do a cable fault location or a diagnosis are one of the most important details that the technician must be aware of.
The purpose of power cables is for the efficient distribution of electrical energy, distribution must be done with a high degree of reliability and safety over a very long period of time. Depending on the application, external environmental and local factors, for example, ground water level, type of ground or voltage levels, different types of cables are used. Cables with impregnated insulation, such as PILC, were installed until be late 60’s and are still being installed in some areas. These cables are today mostly replaced by cables with PVC, EPR, PR or XLPE insulation. Resulting from the changing characteristics of cables their faults and testing have changed considerably.
fiber-mart supply a range of cable fault locators, such as Fluke 2042 cable locator, T-C310 cable fault locator, ST620 Cable Fault Locator and so on. As an professional optical communication products manufacturer, we also offer fiber optic tools and other fiber testers, welcome to contact us.