IEEE 1610:2016 pdf free download – IEEE Guide for the Application of Faulted Circuit Indicatorson Distribution Circuits
3.Application of faulted circuit indicators (FCls)
Underground and overhead FCls are applied to monitor conductors at switchgear, transformers, junctions,cable dips, risers, etc. FCIs are attached to conductors, or test points, to sense for abnormally high currentstypically associated with faults. FCIs trip with a visual, audible, radio, or remote indication when they havesensed conditions that are determined to indicate an overcurrent has passed its location.FCIs located along thefault current path will trip to indicate a “FAULT,”while those that do not determine a fault current has passedits location will remain “NORMAL.” Operating personnel locate the faulted section between the last FCl dis-playing “FAULT”” and the first FCI displaying “NORMAL.””
Circuits can be radial or looped. Looped circuits typically have an open point. When choosing the placementof FCIs,consideration between cost and customer reliability should be made. FCIs could be placed on boththe incoming and outgoing cables of each transformer.This would provide the most knowledge on where thefault is located since information would be available to differentiate between cable faults and faults on the highvoltage bus in the transformer.
Evidence has shown that primary cable faults are much more prevalent than high voltage bus faults in trans-formers, switches, and junctions. To address the problem of cable faults, FCls need only be placed on theoutgoing cables of transformers.Further reduction in the number of FCIs installed could be realized by locat-ing them at every other transformer or less. However, for each reduction in the number of FCIs, the time tolocate and isolate the faulted cable will increase.The customer outage time will also increase.
Faulted circuit indicators are affected by many items including cold load pickup,inrush, switching surges,lightning, and power follow currents.Proper application is essential to proper operation.FCls should avoidtripping on inrush, cold load pickup, and switching surges and operate before protective devices.
3.1 Types of FCls
3.1.1 Manual reset
Manual reset FCls require an operator to check and reset each indicator after each fault event. The large varietyof system conditions that occur on a distribution system makes it very difficult to create generalized applica-tion rules.Failure to reset the indicator can cause confusion for subsequent faults. Mechanical FCls do notemploy inrush restraint.
3.1.2.2 Voltage reset
Voltage resetting fault indicators are not affected by load current.Voltage resetting FCIs can be used onoverhead or underground systems. There are several types of voltage resetting devices. The high and medium(primary) voltage resetting devices depend on the electrostatic field surrounding a high or medium voltagecable or a separable connector ‘s capacitive test point for operating power. The electrostatic reset type requiresthat the cable be unshielded and a test point reset type requires the use of a test point type separable connector.The low (secondary) voltage resetting devices can only be applied wherever a secondary voltage is availableand does not require a “test point type separable connector.”Minimum voltage levels and durations must bemet for proper operation.
3.1.2.3 Time reset
Time reset FCIs will reset after a selected period of time regardless of voltage or current status. When choosingthe length of time before reset, the time chosen should be long enough to allow operating personnel time tolocate and isolate the fault. If some or all of the units reset before this is accomplished, confusing informationas to the location of the fault exists. In contrast, choosing an excessively long time can also cause problems ifthere is a subsequent fault before the units have had a chance to reset.