ABB Relion 670 series, Technical Reference Manual

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SW-time
Time-
Regulator
(fast or slow)
Time tagging and general synchronisation
Time-
Regulator
(Setting,
see
technical
reference
manual)
Comm-
unication
Events
Synchronization for differential protection
(ECHO-mode or GPS)
Diff.-
comm-
unication
*IEC 61850-9-2
Connected when GPS-time is
used for differential protection
IEC08000287-2-en.vsd
External
Synchronization
sources
Trans-
ducers*
LON
SPA
GPS
SNTP
IRIG-B
PPS
Off
Min. pulse
DNP
GPS
IRIG-B
PPS
Off
Protection
and control
functions
A/D
converter
HW-time
IEC08000287 V2 EN
Figure 25: Design of 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 with the function based on free running hardware
clock, the event is time tagged by the software clock when it reaches the event
recorder. Thus the hardware clock can run independently.
The echo mode for the 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 and 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 setting
fast or slow is also available on the local HMI.
If a GPS clock is used for 670 series IEDs other than line differential RED670, the
hardware and software clocks are not synchronized
1MRK505222-UUS C
Section 4
Basic IED functions
85
Technical reference manual