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6.8
Real Time Clock
The relay stores the time and date. The time and date are maintained while the relay is de-energised by a back
up storage capacitor.
The default date is set at 01/01/2000 deliberately to indicate the date has not yet been set. When editing the
Time, only the hours and minutes can be edited. When the user presses ENTER after editing the seconds are
zeroed and the clock begins running.
Time and date can be set either via the relay fascia using appropriate commands in the System Config menu or
via:
6.8.1 Time Synchronisation – Data Comms
Where the data comms channel(s) is connected to a dedicated substation automation system the relay can be
time synchronised using the relevant command within IEC 60870-5-103, DNP3.0 or optional IEC 61850protocols.
The time can also be synchronised from 'Reydisp' which utilises the communications support software.
6.8.2 Time Synchronisation – Binary Input
A binary input can be mapped Clock Sync from BI. The seconds or minutes will be rounded up or down to the
nearest value when the BI is energised. This input is leading edge triggered.
6.8.3 Time Synchronisation – IRIG-B (Optional)
A BNC connector on the relay rear provides an isolated IRIG-B time synchronisation port. The IRIG-B input
expects a modulated 3-6 Volt signal and provides time synchronisation to the nearest millisecond.
6.9
Settings Groups
The relay provides eight groups of settings – Group number (Gn) 1 to 8. At any one time only one group of
settings can be 'active' – SYSTEM CONFIG>Active Group setting.
It is possible to edit one group while the relay operates in accordance with settings from another 'active' group
using the View/Edit Group setting.
Some settings are independent of the active group setting i.e. they apply to all settings groups. This is indicated
on the top line of the relay LCD – where only the Active Group Number is identified. Where settings are group
dependent this is indicated on the top line of the LCD by both the Active Group Number and the View Group
Number being displayed.
A change of settings group can be achieved either locally at the relay fascia, remotely over the data comms
channel(s) or via a binary input. When using a binary input an alternative settings group is selected only whilst the
input is energised (Select Grp Mode: Level triggered) or latches into the selected group after energisation of the
input (Select Grp Mode: Edge triggered).
©2013 Siemens Protection Devices Limited
Chapter 1) 7SR23 DAD Description Of Operation
Chapter 1 Page 34 of 36
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