ABB REG670 - Operation Principle

20.6.3 Operation principle
20.6.3.1 General concepts
Time definitions
The error of a clock is the difference between the actual time of the clock, and the time
the clock is intended to have. Clock accuracy indicates the increase in error, that is, the
time gained or lost by the clock. A disciplined clock knows its own faults and tries to
compensate for them.
Design of the time system (clock synchronization)
The time system is based on software and hardware clocks that run independently
from each other. See figure
501
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 501: Design of the time system (clock synchronization)
Section 20 1MRK502052-UEN B
Basic IED functions
1108
Technical manual