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2.2.1
Functional Description
Acquisision and Mergence of Multi-channel Data
The MU device 6MU805 supports to digitize sample values of 4 currents (1 A/5 A) and 4 voltages (100 V/ 110
V) with 80 samples per cycle for 50 Hz or 60 Hz power grid systems.
The device acquires and merges the sample values from instrument transfomers synchronnously. Current and
voltage measurements are merged into one device and a digital stream is generated from sample values, which
can then serve as an input signal for other protection relays.
Sample Value Synchronization
The main feature of a Merging Unit is generating sample values synchronized by an external synchronization
signal PPS, GPS or IRIG-B. When digitizing sample values, the synchronization of MU is very important for
protection application which needs sample values from different MUs, for example, differential protection ap-
plications. If there are more than one MU devices running in the substation, the SV are synchronized via a
common synchronization signal, so the synchronization signals sent to different MUs should keep high syn-
chronization accuracy. Synchronization signals must be compatible with the international standard IEC61869.
SV synchronization signals, such as PPS, GPS or IRIG-B signal, are supervised and stabilized before they are
used for synchronization of the sample value generation.
The Sample Value Synchronization is active only when:
• parameter 0460 PPS Synchro is configured as ON
• equipped time sync signal module (PPS / IRIG-B module or GPS module )
• accurate time sync signal is received at PPS / IRIG-B module or GPS module
The Sample Value synchronization is independent from the time synchronization settings.
Sample value are generated based on the oscillator of 6MU805 in one of the following cases:
SIPROTEC, 6MU805, Manual
C53000-G1140-C380-5, Release date 06.2018
Functions
2.2 Merging Unit
33
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