Real Time Clock - Siemens 7SR51 Device Manual

Basic Structure of the Device Functionality

2.5 Real Time Clock

2.5

Real Time Clock

In order to allow the correct time recording of events synchronously, devices need a time synchronization.
The device clock function is used to time tag the stored data i.e. demand/data logs, waveform records, fault
records and event records.
The internal device time is maintained in local time. All display time stamps and event logs are displayed in
local time.
In order to maintain synchronizm within a substation, the clock can be synchronized with an external refer-
ence source.
The default date is set at 01/01/2000 deliberately to indicate the date has not yet been set, if the clock
returns to default value the device will generate an event.
Time and date can be set either via the relay fascia in the Configuration > Device menu or via the data
comms channel(s). When editing the time from the fascia, only the hours and minutes can be edited. When
the user presses Enter after editing, the seconds are zeroed and the clock begins running.
In the event of loss of auxiliary power the real time clock is powered from a back up storage capacitor.
Setting the Time Source
Parameters for 2 main clocks can be set in a device using the device settings.
If a communication protocol with time synchronization possibilities is available in a device, then the time
sources can be configured as desired.
[sc_7SR5_DeviceSettings, 1, --_--]
NOTE
i
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The source for the master and back up clock must be set to be from different sources.
•
Failure to receive a periodic time synch from the master clock will result in a master clock lost event/
alarm. The period before raising the alarm is the user setting Master Time Synch Lost Delay.
•
Failure to receive a periodic time synch from the master clock will result in a switch over to the backup
clock (if configured). The period before switching over to the backup clock is the user setting Master
Time Synch Lost Delay.
36 Reyrolle 7SR5, Overcurrent Protection Device, Device Manual
C53000-G7040-C014-1, Edition 11.2019