Siemens siprotec 7SA6 User Manual page 182

Configuration
Synchronization
Offset
Annunciation due
to Missing
Synchronization
Changing the
Synchronization
Mode
Operating
Messages from the
Timing System
Time Format
5-58
When using radio clock signals, you must take into account that it can take up to three
minutes after device start-up or restored reception for the received time signal to be
decoded. The internal clock is not re-synchronized until then.
With IRIG B, the year must be set manually, because this standard does not include
a year value.
For synchronization using pulses via a binary input, the present device time will
advance to 00 seconds of the next minute for values greater than 30 seconds when
the positive slope of the pulse arrives. For second values less than 30, the device time
will be set to 00 seconds of the current minute. Because this signal is not monitored,
each pulse has a direct effect on the internal clock.
The "Synchronization Offset" (2IIVHW) setting allows correlation of the time signal
received from the radio clock to local time (time zone). The maximum settable offset
is ± 23 h 59 min = ±1439 min.
The tolerance time ((UURU 7LPH / )DXOW LQGLFDWLRQ DIWHU) for time
synchronization fault indicates how long cyclical synchronization may be absent until
an alarm is given.
External or internal synchronization normally occurs every minute. The setting for the
tolerance time must, therefore, always be at least two minutes. Under poor radio clock
reception conditions, you may delay the trigger of the "error" status condition even
longer.
When changing synchronization mode, the hardware will change over to the new
source within one second. This causes breakdown of cyclical synchronization, and the
internal clock will be disrupted — as at start-up — until the new synchronization
source takes over.
After modification to the synchronization offset in the time signal/operating mode, or
when changing year in IRIG B, the cyclical synchronization is not lost, but there is a
jump. To call attention to this, the time value causing a jump is reported with "7LPH
LQWHUUXSWLRQ 21" — without the synchronization offset, and subsequently with
"7LPH LQWHUUXSWLRQ 2))" — with the synchronization offset.
After the "7LPH LQWHUUXSWLRQ 21" message, you must take into account that the
clock will jump. This message is issued under the following circumstances:
− if a synchronization interruption lasts longer than the tolerance time interval
mentioned above, or as mentioned above, if the synchronization mode is changed;
− if a time jump is anticipated. The message itself is stamped with the old time.
The message "7LPH LQWHUUXSWLRQ 2))" is triggered:
− when the synchronization is re-established (e.g., after a break in reception by the
radio clock);
− immediately after a time jump. This message is stamped with the new time after the
jump, thus allowing determination of the jump interval.
The time display may be set using either the European format (DD.MM.YYYY) or the
US format (MM/DD/YYYY).
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7SA6 Manual
C53000-G1176-C133-1