1MRS750527-MUM
REF 54_
83
Feeder Terminal
Technical Reference Manual, General
For more information about asynchronous blockings refer to the horizontal
communication engineering tip in the Protection & Control Terminals REF 54_,
RET 54_, REM 54_, REC 523 Configuration Guideline.
5.1.14. Time synchronization
The internal clock of the REF54_ relay unit can be set from different sources:
1. The time can always be given manually from the front panel
(Configuration\General\Date, Configuration\General\Time).
2. The time synchronization can also be set externally, either by a communication
protocol or by a binary input. The parameter (Configuration\
General\Timesync source) is used for selecting the source for external
synchronization. The parameter has two states Comm. channel (default) and
Input X5.2/1,2.
When Comm. channel is selected, the system clock is adjusted according to time
synchronization messages from any of the supported communication protocols.
When parallel communication is used, the user has to make sure that
synchronization messages are received from only one communication channel.
When Input X5.2/1,2 is selected, the relay expects a pulse train on
the X5.2/1,2 binary input with a period of either one minute or one second. Note that
Input X5.2/1,2 must be in binary input mode and not in counter mode
(Configuration\BIO1 [5]\Input mode\Input 12 mode). The system
clock will be rounded to the nearest whole second or minute, depending on the
period of the pulse train, on the rising edge of the input. If synchronization on falling
edge is desired, the input can be inverted by setting the parameter
Configuration\BIO1 [5]\Input inversion\Input 12 invert to
Enabled. If time synchronization messages are also received from a
communication protocol, they are accepted, but only the year-month-day-hour-
minute-second part is written to the internal clock. Therefore a communication
protocol such as SPA can be used to set the internal clock with a coarse time and
simultaneously the binary input is used to fine-tune the accuracy.
Note that the clock of the protocol master and the pulse train on the
binary input must be synchronized, with a deviation always less than
500 ms, otherwise the internal clock of the relay will make sudden
one second jumps in either direction.
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