First you should know what is called a fault indicator.
According to definition of the "distribution line fault indicator technical specifications" , distribution line fault indicator is the device which is installed on the distribution Line for the detection of short circuit and single-phase earth fault, and then will send the alarm information. "
When the fault occurs to the line, patrol officers can quickly determine the fault section according to the alarm display of the fault indicator, and find the location of fault.
According to the use of different places, fault indicators can be divided into overhead fault indicator , cable line fault indicator. The definition of the Cable Line fault indicator is the device whose "sensor and display (indicating) part is integrated in a unit and is mechanically fixed to a phase Cable lines, usually installed in the cable branch box , Ring Main Unit, Switchgear and other power distribution equipment"
 
The remote fault indicator refers to the "telemetry" and "remote communication". Compared to a local fault indicator that only indicates a fault mechanically, remote fault indicator can also collect the real-time load current value on the corresponding line to achieve a "telemetry" function.
 
As an important measurement point of distribution network automation system, the cable line fault indicator plays an important role to shorten the power outrage time, improve power supply reliability, maintain high customer satisfaction of power supply utility and to avoid the economic losses of production enterprises, and ultimately to promote the level of productivity of society. It is no exaggeration to say that the widespread use of cable line fault indicators can produce significant Benefit and social benefits!