ABB RELION REX640 Technical Manual page 119

1MRS759142 C
REX640
Technical Manual
If the current master is not within the 1 µs accuracy, ALARM is set to TRUE. If the
current master is not the saved primary master, WARNING is set to TRUE. The
EXTCLKMSTR output indicates if the current master is external.
Since the list is updated via the current primary master in the network, it is possible to
lower the current grandmasters priority to a point where another clock takes the role
and the priority value in the list for the original master is no longer updated. This
means that there is a discrepancy between the list and the device. Consequently, the
GNRLLTMS warning status becomes TRUE as the saved primary master is no longer
considered as connected. The list logic can be reset to clear the clock list.
When IEEE 1588 v2 time synchronization is used, the recommended
maximum number of hops from the grandmaster is 15 to ensure that
the accuracy stays within 1 µs.
IRIG-B
IRIG-B time synchronization requires IRIG-B format B00x and IRIG-B time code
extensions according to IEEE Std C37.118.1
the Annex D.
The synchronization time in IRIG-B can be either UTC time or local time. As no
reboot is necessary, the time synchronization starts immediately after the IRIG-B
synchronization source is selected and the IRIG-B signal source is connected.
GNRLLTMS signals reflect the signal status from the IRIG-B master.
IRIG-B time synchronization requires a COM module with an IRIG-
B input.
DNP3, Modbus, IEC 60870-5-101/104 and IEC 60870-5-103
With DNP3 the synchronization interval can be set manually. The synchronization
message must be received within a minute after the synchronization interval has
expired. Otherwise bad synchronization status is raised for the protection relay.
With Modbus, IEC 60870-5-101/104 and IEC 60870-5-103 the synchronization
message must be received within four minutes from the previous synchronization.
Otherwise bad synchronization status is raised for the protection relay.
When Modbus TCP or DNP3 over TCP/IP is used, PTP, SNTP or
IRIG-B time synchronization is recommended to be used for better
synchronization accuracy.
Basic functions
TM
-2011. The extensions are defined by
Section 3
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