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8
8.2 Synchronization Types
105
Digital Fault Recorder, SIMEAS R-PMU, Manual
E50417-H1076-C360-A5, Release 10.2012
8.2 Synchronization Types
8.2.1 Minute Pulse Synchronization
The minute pulse synchronization corrects the drift of the SIMEAS R-PMU real-time clock every
minute. For this purpose, the SIMEAS R-PMU adjusts the RTC in such a way that the minute
change exactly matches the synchronization pulse. Time information (date, time) is not sent
together with the minute pulse. This is why the device time must be set manually during
commissioning and after a longer pulse failure (several days). See chapter 9,
Setting the Time
.
As the drift may be
±
1.8 ms within one minute at a temperature of 25
°
C, the minute pulse
synchronization is not suitable for the operation of the SIMEAS R-PMU Phasor Measurement
Unit. The DCF77 synchronization is the only suitable method for this application.
8.2.2 GPS Synchronization via DCF77 Second Signal
The GPS synchronization allows precise synchronizing of the SIMEAS R-PMU and correct time
stamping of the records. The pulse-width modulated digital DCF77 second signal of the timer
contains the date, time (UTC = Coordinated Universal Time) and further information which is
required for setting the time on the device automatically.
Leap seconds (additionally inserted second(s) for synchronizing the "mean solar time") are also
announced via DCF77 and processed by the SIMEAS R-PMU. The PMU data is marked
according to the standard during leap seconds.
The operation of the Phasor Measurement Unit of the SIMEAS R-PMU puts high demands on
timer accuracy. The total vector error (TVE) of the PMU amounting to
≤
1 % can only be observed
if the synchronization signal has a precision of 5 µs. It is therefore recommended only to use the
GPS timer mentioned in the following chapter and to carefully observe the adjustment
instructions.