Data Storage; Waveform Records; Event Records - Siemens 7SG11 Technical Manual

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System frequency
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Output relay status
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Digital input status
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General alarm screen
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Trip counter
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Power on counter
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Number of waveforms recorded
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Number of events stored
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Date - displayed in DD/MM/YY format
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Time - displayed in HH:MM:SS format
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Starter information for Voltage, Frequency, NPS and NVD elements
Note : the instrument displays are updated as often as the software routines can service them, however the RMS
voltage measurands have a response time of approximately 500msec.
Figure 5 shows the display menu structure from where the available instruments can be accessed. Note that
pressing the Test/Reset key can clear three of the instruments, the Trip Counter, Waveforms and Events.

4.2 Data Storage

Details of relay operation are recorded in three forms, namely Waveform records, Event records and Fault Data
records. All records are time and date stamped with a year 2000 compatible real time clock which maintains the
time even when the relay is de-energised [see Note below]. Time and date can be set either via the relay fascia
using appropriate commands in the System Config menu or via the communications interface. In the latter case,
relays connected in a network can be synchronised by a global time sync command.
Alternatively, synchronising pulses can be received via a status input. To use this feature one of the status inputs
has to be assigned to the 'Clock Sync' feature in the Status Config menu. Additionally the 'Clock Sync Period'
setting in the System Config menu should be set to either 'seconds' or 'minutes'. If 'seconds' are selected then the
energisation of the selected status input will result in the clock being synchronised to the nearest second with the
milliseconds set to zero. If 'minutes' are selected then the clock is synchronised to the nearest minute with both
seconds and milliseconds set to zero.
Note : the real-time clock, waveform records and event records are all maintained, in the event of loss of auxiliary
d.c. supply voltage, by the backup storage capacitor. This capacitor has the ability to maintain the charges on the
real-time clock IC and the SRAM memory device for typically 2-3 weeks time duration. This time, however, is
influenced by factors such as temperature and the age of the capacitor and could be shorter.

4.2.1 Waveform Records.

The waveform record feature stores analogue and digital information for the voltage inputs, status inputs and
output relays. The waveform record is 1.0 second long (0.833sec at 60Hz) with a sampling resolution of 16
samples per cycle. The recorder feature has the ability to store records for the previous five trip operations of the
relay. These are labelled 1-5 with 1 being the most recent record.
The waveform recorder can be triggered in the following ways ;
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Via the waveform trigger status input signal.
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From any element Trip operation, including, Voltage, Frequency, NVD and NPS elements.
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Via the IEC870-5-103 communications interface.
The waveform recorder has a settable pre-fault triggering capability.

4.2.2 Event Records

The event recorder feature allows the time tagging of any change of state (event) of 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 5ms. There is
capacity for a maximum of 500 event records to be stored in the relay and when the event buffer is full, any new
record will over-write the oldest. The following events are logged :
©2011 Siemens Protection Devices Limited
7SG11 Argus 8 Description of Operation
Chapter 1 Page 11 of 20