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Synchronizing Two or More CMC Test Sets
5.2 Enhanced Accuracy Mode
For applications with very high requirements of synchronization accuracy, the
enhanced accuracy mode is provided. In this mode, the start of a test sequence
can be synchronized with a timing error of less than 5 µs. Typically this error is
in range of only 1 µs
1
.
When using this mode, there is a special behaviour of the test equipment, which
has to be considered. The test set enters a type of wait condition some
milliseconds prior to the expected occurrence of the GPS pulse.
During this wait,
there is no output of signals.
Figure 5-3:
Behaviour of the
Enhanced Accuracy
Mode
Other restrictions with the enhanced accuracy mode are:
• It applies to the test sets CMC 256, CMC 256plus, CMC 353, CMC 356 and
CMC 850, only.
• Supported by a selected range of test modules only (e.g., State Sequencer)
• The specified precision refers to the first state (start state) of a sequence
• Concurrent operation of the EnerLyzer is not supported.
Note that the 5 µs accuracy is restricted to the test start only. It does not apply
to actions triggered by the following GPS pulses
2
.
1. Error corresponds to amplifier output signals (voltage/current) of CMGPS-synchronized test sets
at configured GPS trigger event.
2. Together with the CMIRIG-B extension box, CMC outputs can be resynchronized with each
1PPS CMGPS pulse.
GPS output pulse
Analog output
Waiting condition - no output
Falling slope is within
± 1 μs to
programmed time at both sides
Time difference
< 5 μs (typ.
≈ 1 μs)
Substation A
Substation B
first zero crossing
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