3.2 System clock accuracy
All signals generated or measured by the CMC 430 refer to a common internal time base that is
specified as follows:
Characteristic Specification
Clock performance Stratum 3 (ANSI/T1.101-1987)
Frequency drift (over time)
24 hours
20 years
< ±0.37 ppm (±0.000037 %)
< ±4.60 ppm (±0.00046 %)
Frequency drift (over temperature range) < ±0.28 ppm (±0.000028 %)
Frequency resolution (signal generation) < 5 μHz
3.3 Synchronization
Synchronization of system clock
By synchronizing the system clock to an external time base, the system clock accuracy can be
improved up to the level of the external time base. Synchronizing the system clock additionally makes
the absolute time available in the system to tag measurement results, start distributed tests at the
same time, and generate and measure synchrophasors.
The following specifications refer to the internal time base. For the absolute time accuracy of the
outputs and inputs, the inherent error of the respective channel itself has to be added.
Characteristic Specification
IEEE 1588-2008 (v2)
Offset (UTC)
Pulling range
Supported profiles
Supported sources
Error < ±1 µs
±100 ppm (±0.01 %)
IEEE C37.238-2011 (Power Profile)
IEC/PAS 61850-9-3: Communication Networks and Systems for
Power Utility Automation – Part 9-3: Precision Time Protocol Profile
for Power Utility Automation (Utility Profile)
OMICRON CMGPS 588 or any Precision Time Protocol source
(PTP grandmaster clock)
IRIG-B
Offset (UTC)
Pulling range
Supported sources
Error < ±5 μs
±100 ppm (±0.01 %)
Third-party IRIG-B sources with OMICRON CMIRIG-B accessory
Synchronization of voltage and current output signals
The phase and frequency of the voltage and current outputs can be synchronized to a reference input
signal of 15 ... 70 Hz applied to binary input 6. In contrast to the synchronization of the system clock,
this kind of synchronization influences the frequency and phase of the signal generation directly.
CMC 430 User Manual
18
OMICRON
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