Operation Principle - ABB REC650 Technical Manual

Section 12
Monitoring
12.9.5
12.9.5.1
462

Operation principle

Disturbance recording is based on the acquisition of binary and analog signals. The
binary signals can be either true binary input signals or internal logical signals
generated by the functions in the IED. The analog signals to be recorded are input
channels from the Transformer Input Module (TRM) through the Signal Matrix
Analog Input (SMAI) and possible summation (Sum3Ph) function blocks and some
internally derived analog signals.
Disturbance recorder collects analog values and binary signals continuously, in a
cyclic buffer. The pre-fault buffer operates according to the FIFO principle; old data
will continuously be overwritten as new data arrives when the buffer is full. The size
of this buffer is determined by the set pre-fault recording time.
Upon detection of a fault condition (triggering), the disturbance is time tagged and the
data storage continues in a post-fault buffer. The storage process continues as long as
the fault condition prevails - plus a certain additional time. This is called the post-fault
time and it can be set in the disturbance report.
The above mentioned two parts form a disturbance recording. The whole memory,
intended for disturbance recordings, acts as a cyclic buffer and when it is full, the
oldest recording is overwritten. Up to the last 100 recordings are stored in the IED.
The time tagging refers to the activation of the trigger that starts the disturbance
recording. A recording can be trigged by, manual start, binary input and/or from
analog inputs (over-/underlevel trig).
A user-defined name for each of the signals can be set. These names are common for
all functions within the disturbance report functionality.
Memory and storage
The maximum number of recordings depend on each recordings total
recording time. Long recording time will reduce the number of
recordings to less than 100.
The IED flash disk should NOT be used to store any user files. This
might cause disturbance recordings to be deleted due to lack of disk
space.
When a recording is completed, a post recording processing occurs.
This post-recording processing comprises:
• Saving the data for analog channels with corresponding data for binary signals
• Add relevant data to be used by the Disturbance handling tool (part of PCM 600)
• Compression of the data, which is performed without losing any data accuracy
• Storing the compressed data in a non-volatile memory (flash memory)
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Technical manual