ABB REL 551-C1*2.5, Technical Reference Manual

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Disturbance recorder (DR) Chapter 8
Monitoring
3 Disturbance recorder (DR)
3.1 Application
Use the disturbance recorder to record analog and binary signals during fault conditions in order
to analyze disturbances. The analysis may include fault severity, fault duration and protection
performance. Replay the recorded data in a test set to verify protection performance.
3.2 Functionality
The disturbance recorder records both analog and binary signal information and up to ten distur-
bances can be recorded.
Analog and digital signals can be used as triggers. A trigger signal does not need to be recorded.
A trigger is generated when the analog signal moves under and/or over set limit values. The trig
level is compared to the signal’s average peak-to-peak value, making the function insensible to
DC offset. The trig condition must occur during at least one full period, that is, 20 ms for a 50 Hz
network.
The recorder continuously records data in a cyclic buffer capable of storing the amount of data
generated during the set pre-fault time of the collection window. When triggered, the pre-fault
data is saved and the data for the fault and post-fault parts of the collection window is recorded.
The RAM area for temporary storage of recorded data is divided into subareas, one for each re-
cording. The size of a subarea depends on the set recording times. There is sufficient memory
for four consecutive recordings with a maximum number of analog channels recorded and with
maximum time settings. Should no subarea be free at a new disturbance, the oldest recording is
overwritten.
When a recording is completed, the post recording process:
• merges the data for analog channels with corresponding data for binary signals
stored in an event buffer
• compresses the data without loosing any data accuracy
• stores the compressed data in a non-volatile memory
The disturbance recordings can be viewed via SMS or SCS.