Underground

In underground applications, a utility usually places a fault indicator on each transformer (installed on the outgoing phase as shown in the diagram above). If a fault causes a feeder fuse to operate, the indicators upstream of the fault trip, and the indicators after the fault remain in the untripped position. As a result, the utility can easily identify the faulted section of cable without going through a time-consuming re-fuse and sectionalize process. Underground applications include subsurface or padmounted transformers, subsurface or padmounted switchgear and sectionalizing cabinets, junction boxes, and splices. The RadioRANGER™ Wireless Fault Indication System, designed for underground vault applications, uses radio frequency to communicate fault status to a handheld Remote Fault Reader.

Overhead

When a fault occurs on an overhead system, the easy-to-spot displays on the SEL fault indicators lead the line crew to the faulted section of line. Overhead applications include unfused taps, long feeders with midline reclosers or sectionalizers, overhead-to-underground transitions, and feeders that experience recurring faults. Applying fault counters and timed reset fault indicators in areas affected by momentary outages and flickering lights is an efficient means of identifying the location of temporary faults. This application of fault indicators, designed to locate temporary faults, provides utilities with the information to resolve these disruptions. Using fault indicators as a tool reduces costs to utilities and their customers and improves utilities’ reliability indices.