GE Multilin 850, Instruction Manual

Page: 205 / 664

CHAPTER 5: DEVICE, SYSTEM, INPUT AND OUTPUT SETPOINTS DEVICE
850 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL 5–43
Fault Reports
The 850 relay supports up to 15 fault reports and an associated fault locator before
overwriting the oldest one. The trigger conditions and the characteristics of the feeder, as
well as the analog quantities to be stored, are entered in this menu.
When enabled, this function monitors the pre-fault trigger. The pre-fault data are stored in
the memory for prospective creation of the fault report on the rising edge of the pre-fault
trigger. The element waits for the fault trigger as long as the pre-fault trigger is asserted,
but not shorter than 1 second. When the fault trigger occurs, the fault data is stored and
the complete report is created. If the fault trigger does not occur within 1 second after the
pre-fault trigger drops out, the element resets and no record is created.
The user-programmable fault report contains a header with the following information:
•
Relay model
• Device name
• Firmware revision
• Date and time of trigger
• Name of pre-fault trigger (FlexLogic operand)
• Name of Fault trigger (FlexLogic operand)
• Active setting group at the time of pre-fault trigger
• Active setting group at the time of fault trigger.
The fault report continues with the following information:
•
All current and voltage phasors (one cycle after the fault trigger)
• Pre-fault values for all programmed analog channels (one cycle before pre-fault
trigger)
• Fault values of all programmed analog channels (one cycle after the fault trigger)
Each Fault Report created can be saved as a text file using the EnerVista 8 Series Setup
software. The file names are numbered sequentially to show which file is older than the
other.
The captured data also includes the fault type and the distance to the fault location, as
well as the reclose shot number (when applicable).
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. A FAULT RPT TRIG event is automatically created when the report is triggered.
If a number of protection elements, such as overcurrent elements, are “OR’d” to create a
fault report trigger, the first operation of any element causing the OR gate output to
become high triggers the 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 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.
The fault report stores data, in non-volatile memory, pertinent to an event when triggered.
Each fault report is stored as a file to a maximum capacity of fifteen (15) files. A sixteenth
(16th) trigger overwrites the oldest file.