SW time
Time
regulator
(fast or slow)
Time tagging and general synchronization
Time
regulator
(Setting:
see
Technical
manual)
Commu-
nication
Events
Synchronization for differential protection
(Echo mode)
Diff.
commu-
nication
*IEC 61850-9-2
IEC16000002-2-en.vsdx
External
synchronization
sources
Trans-
ducers*
LON
SPA
SNTP
IRIG-B
PPS
Off
Min. pulse
DNP
IRIG-B
PPS
Off
Protection
and control
functions
A/D
converter
HW time
IEC16000002 V2 EN
Figure 502: Design of the time system (clock synchronization)
All time tagging is performed by the software clock. When, for example, a status
signal is changed in the protection system of a function based on the free running
hardware clock, the event is time tagged by the software clock when it reaches the
event recorder. The hardware clock can thus run independently.
The echo mode of differential protection is based on the hardware clock. Thus, there
is no need to synchronize the hardware clock and the software clock.
The synchronization of the hardware clock to the software clock is necessary only
when GPS or IRIG B 00X with optical fibre, IEEE 1344 is used for differential
protection. The two clock systems are synchronized by a special clock
synchronization unit with two modes, fast and slow. A special feature, an automatic
fast clock time regulator is used. The automatic fast mode makes the synchronization
time as short as possible during start-up or at interruptions/disturbances in the GPS
timing. The fast and slow settings are also available on the local HMI.
The hardware and software clocks are not synchronized if a GPS clock is used.
Fast clock synchronization mode
At start-up and after interruptions in the GPS or IRIG B time signals, the deviation
between the GPS time and the internal differential time system can be substantial. A
1MRK502052-UEN B Section 20
Basic IED functions
1109
Technical manual
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