Data Storage; General; Event Records; Waveform Records - Siemens 7SR242 Duobias Technical Manual

6.4

Data Storage

6.4.1 General

The relay stores three types of data records: relay event records, analogue/digital waveform records and fault
data records. These data records are backed up in non-volatile memory and are permanently stored even in the
event of loss of auxiliary d.c. supply voltage.

6.4.2 Event Records

The event recorder feature allows the time tagging of any change of state (Event) in the relay. As an event
occurs, the actual event condition is logged as a record along with a time and date stamp to a resolution of 1
millisecond. There is capacity for a maximum of 5000 event records that can be stored in the relay and when the
event buffer is full any new record will over-write the oldest. Stored events can be erased using the DATA
STORAGE>Clear Events setting.
The following events are logged:
Change of state of Binary outputs.
Change of state of Binary inputs.
Change of Settings and Settings Group
Change of state of any of the control functions of the relay.
All events can be uploaded over the data communications channel(s) and can be displayed in the 'ReyDisp
Evolution' package in chronological order, allowing the sequence of events to be viewed. Events are also made
available spontaneously to an IEC 60870-5-103 or Modbus RTU compliant control system.
For a complete listing of events available in each model, refer to Technical Manual Chapter 4 'Data Comms'.

6.4.3 Waveform Records.

Waveform records provide a trace of the instantaneous magnitude of each analogue input channel and the status
of each binary channel i.e. each binary input, binary output, virtual I/O and LED, against time for the duration of
the record. The values are recorded at every digital sampling point used by the relay software.
Each recorded analogue waveform displays an input identifier, minimum value, maximum value and the
instantaneous values at both cursor positions (user variable). Each binary waveform displays the input/output
number and the initiating condition(s) e.g. external input or protection element.
Triggering of waveform storage is configured from the 'Settings > DATA STORAGE > WAVEFORM STORAGE'
menu. Triggering is automatically initiated from operation of any of the selected protection or control elements.
Waveform storage can also be triggered from the relay fascia, from a suitably programmed binary input or via the
data comms channel(s).
Waveforms are sampled at a rate of 32 samples per cycle.
The latest 100 records are stored, the most recent is waveform 1. Records are archived by the relay during
quiescent periods. The duration of each stored record is 1s, 2s, 5s or 10s. The percentage of waveform storage
prior to waveform triggering is user configurable. When the waveform archive buffer is full (i.e. 100 records are
stored) the triggering of a new waveform record causes the oldest record - waveform 100 – to be overwritten.
Stored waveforms can be deleted from the relay fascia using the DATA STORAGE > Clear Waveforms setting or
via Reydisp.
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Chapter 1) 7SR242 Duobias Description Of Operation
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