Event Recording; Disturbance Recorder; Fault Locator - GE MiCOM P40 Agile Technical Manual

Chapter 4 - Software Design
5.8

EVENT RECORDING

A change in any digital input signal or protection element output signal is used to indicate that an event has taken
place. When this happens, the protection and control task sends a message to the supervisor task to indicate that
an event is available to be processed and writes the event data to a fast buffer controlled by the supervisor task.
When the supervisor task receives an event record, it instructs the platform software to create the appropriate log
in non-volatile memory (battery backed-up SRAM). The operation of the record logging to battery backed-up SRAM
is slower than the supervisor buffer. This means that the protection software is not delayed waiting for the records
to be logged by the platform software. However, in the rare case when a large number of records to be logged are
created in a short period of time, it is possible that some will be lost, if the supervisor buffer is full before the
platform software is able to create a new log in battery backed-up SRAM. If this occurs then an event is logged to
indicate this loss of information.
Maintenance records are created in a similar manner, with the supervisor task instructing the platform software to
log a record when it receives a maintenance record message. However, it is possible that a maintenance record
may be triggered by a fatal error in the relay in which case it may not be possible to successfully store a
maintenance record, depending on the nature of the problem.
For more information, see the Monitoring and Control chapter.
5.9

DISTURBANCE RECORDER

The disturbance recorder operates as a separate task from the protection and control task. It can record the
waveforms for up to 12 calibrated analog channels and the values of up to 32 digital signals. The recording time is
user selectable. Up to 50 seconds of data can be recorded. A minimum number of 5 records with a capacity of 10
seconds each, up to a maximum of 50 records with a capacity of 10 seconds each can be set. The disturbance
recorder is supplied with data by the protection and control task once per cycle. The disturbance recorder collates
the data that it receives into the required length disturbance record. The disturbance records can be extracted by
settings application software such as MiCOM S1 Agile, which can also store the data in COMTRADE format,
therefore allowing the use of other packages to view the recorded data.
For more information, see the Monitoring and Control chapter.
5.10

FAULT LOCATOR

The fault locator uses 12 cycles of the analog input signals to calculate the fault location. The result is returned to
the protection and control task, which includes it in the fault record. The pre-fault and post-fault voltages are also
presented in the fault record. When the fault record is complete, including the fault location, the protection and
control task sends a message to the supervisor task to log the fault record.
The Fault Locator is not available on all models.
5.11 FUNCTION KEY INTERFACE
The function keys interface directly into the PSL as digital input signals. A change of state is only recognized when
a key press is executed on average for longer than 200 ms. The time to register a change of state depends on
whether the function key press is executed at the start or the end of a protection task cycle, with the additional
hardware and software scan time included. A function key press can provide a latched (toggled mode) or output
on key press only (normal mode) depending on how it is programmed. It can be configured to individual protection
scheme requirements. The latched state signal for each function key is written to non-volatile memory and read
from non-volatile memory during relay power up thus allowing the function key state to be reinstated after power-
up, should power be inadvertently lost.
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