Micom P721, Technical Manual

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P72x/EN AP/C21 Application Guide
Page 48/52 MiCOM P721/P723
9. EVENT RECORDS
The relay records and time tags up to 250 events and stores them in a non-volatile (flash)
memory. This allows the system operator to analyze the sequence of events that occurred in
the relay after a particular power system condition, or switching sequence. When the
available space is used up, the new fault automatically overwrites the oldest fault.
The relay’s real time clock time tags each event with a resolution of 1 ms.
The user can view event records through the front panel interface, through the EIA (RS) 232
port, or remotely, through the rear EIA (RS) 485 port.
10. FAULT RECORDS
Each time any of the programmed thresholds are crossed, a fault record is created and
stored in memory. The fault record tags up to 25 faults and stores them in non-volatile (flash)
memory. This allows the system operator to identify and analyze network failures. When the
available memory space is used up, the new fault automatically overwrites the oldest fault.
To view actual fault records, select RECORD > Fault Record , which can display up to 25
stored records. These are records such as fault flags and fault measurements. The time
stamp in the fault record is more accurate than the corresponding time stamp in the event
record. This is because events are logged some time after the actual fault record happens.
The user can view event records through the front panel interface, through the EIA (RS) 232
port, or remotely, through the rear EIA (RS) 485 port.
11. INSTANTANEOUS RECORDER
Each time any of programmed thresholds are crossed, an instantaneous record is created
and displayed under
RECORDS > Instantaneous .
The last five instantaneous records are displayed showing the number of faults, hour, date,
origin (crossing of 87N, 95N, 87 and 95 thresholds), duration, and if the crossing of the
threshold led to a trip or not.
12. DISTURBANCE RECORDER
The disturbance recorder has its own dedicated memory space. Up to 5 disturbance records
of 3 seconds duration each can be stored. When the available memory space is used up,
the new record automatically overwrites the oldest record.
Samples are taken 32 times per cycle.
Each disturbance record consists of analog and digital channels. The relevant CT ratios for
the analog channels are also extracted to enable scaling to primary quantities. The following
table shows the
RECORD > Disturb Record menu.
SETTING RANGE
MENU TEXT
MIN MAX
STEP SIZE
Disturb Record
Pre-Time 100 ms 3000 ms 100 ms
Post-Time 100 ms 3000 ms 100 ms
Disturb Rec Trig On Instantaneous On Trip
The total available disturbance recording time is 6.0 s (pre-trigger time plus post-trigger
time).
For example, using the default settings, if the pre-trigger time time is set to 100 ms and the
post–trigger time to 2.5 s, the total disturbance recording time is 2.6 s.