GE L90 Instruction Manual page 338

PRODUCT SETUP
The L90 incorporates a multi-ended fault locator method based on the synchronized voltage and current measurements
at all ends of the transmission line. This makes it possible to compute the fault location without assumptions or
approximations. This fault locator method is applicable on both two-terminal and three-terminal applications, with results
computed independently at each terminal. For three-terminal line applications, the fault locator is reports the exact line
segment at which the fault occurred and the distance to the fault from the terminal adjacent to the fault.
if charging current compensation is configured and enabled, the line charging current is removed at each terminal for
improved accuracy.
During communication channel failures, the L90 uses the single-ended algorithm to calculate and report fault location.
When the single-ended algorithm is used for three-terminal line applications, the faulted segment of the line is not
determined and reported.
The L90 relay supports one fault report and an associated fault locator per CT bank to a maximum of four. The signal
source and trigger condition, as well as the characteristics of the line or feeder, are entered in this menu.
The fault report stores data, in non-volatile memory, pertinent to an event when triggered. The captured data contained in
the FaultReport.txt file includes:
• Fault report number
• Name of the relay, programmed by the user
• Firmware revision of the relay
• Date and time of trigger
• Name of trigger (specific operand)
• Line or feeder ID via the name of a configured signal source
5
• Active setting group at the time of trigger
• Pre-fault current and voltage phasors (two cycles before either a 50DD disturbance associated with fault report
source or the trigger operate). Once a disturbance is detected, pre-fault phasors hold for three seconds waiting for the
fault report trigger. If trigger does not occur within this time, the values are cleared to prepare for the next disturbance.
• Fault current and voltage phasors (one cycle after the trigger)
• Elements operated at the time of triggering
• Events — Nine before trigger and seven after trigger (only available via the relay web page)
• Fault duration times for each breaker (created by the breaker arcing current feature)
The captured data also includes the fault type, the distance to the fault location, distance to the fault location, fault loop
impedance, as well as the reclose shot number (when applicable). To include fault duration times in the fault report, enable
and configure the breaker arcing current feature for each of the breakers. Fault duration is reported on a per-phase basis.
The relay allows locating faults, including ground faults, from delta-connected VTs. In this case, the missing zero-sequence
voltage is substituted either by the externally provided neutral voltage (broken delta VT) connected to the auxiliary voltage
channel of a VT bank, or by the zero-sequence voltage approximated as a voltage drop developed by the zero-sequence
current, and user-provided zero-sequence equivalent impedance of the system behind the relay.
The trigger can be any FlexLogic operand, but in most applications it is expected to be the same operand, usually a virtual
output, that is used to drive an output relay to trip a breaker. To prevent the overwriting of fault events, do not use the
disturbance detector to trigger a fault report. A FAULT RPT TRIG event is automatically created when the report is triggered.
If a number of protection elements are ORed to create a fault report trigger, the first operation of any element causing the
OR gate output to become high triggers a fault report. However, If other elements operate during the fault and the first
operated element has not been reset (the OR gate output is still high), the fault report is not triggered again. Considering
the reset time of protection elements, there is very little chance that a fault report can be triggered twice in this manner. As
the fault report must capture a usable amount of pre and post-fault data, it cannot be triggered faster than every 20 ms.
Each fault report is stored as a file; the relay capacity is 15 files. A 16th trigger overwrites the oldest file.
Individual fault report features store their files in the same memory space. The sixteenth report overwrites the first one
regardless of which fault report feature produced the sixteenth and the first records.
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FAULT REPORT 1 Z0M
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MAG: 0.00 Ω
L90 LINE CURRENT DIFFERENTIAL SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS
Range: 0.00 to 650.00 ohms in steps of 0.01