Metering Function Plus
The Metering Function Plus module extends the range of metering functions to include harmonic and waveform analysis.
Harmonic analysis
The Metering Function Plus module senses the current and voltage, saves the measured values, and carries out a fast Fourier transformation. The result is the distribution of the harmonics (in %) up to the 29th harmonic. The calculated values are made available via the CubicleBUS and can be displayed in WinPM.Net and the BDA (see Chapters 3 and 4). They can also be saved as an
The harmonic analysis enables not only the quality of the network to be analyzed and logged but also provides settable alarm levels.
Waveform buffer
The Metering Function Plus module features two independent waveform buffers (A and B). Each one has 8 channels, one each for currents Ia, Ib, Ic, IN, and Ig, and voltages Va, Vb, and Vc. Each channel is sensed with a frequency of 1,649 kHz and the values are "pushed" through a shift register (length: 1 second). The process of pushing data through the shift register can be aborted by a configurable trigger event. Trigger events include trips, warnings and setpoint alarms so that the voltage waveform, for example, can be recorded in the event of undervoltage tripping.
Communication-capable Circuit Breakers
WL Circuit Breaker
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Figure | The Metering Function Plus analyzes the harmonics. This screenshot from the WinPM.Net |
system shows how the analysis results are displayed. | |
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Figure | Metering Function PLUS can record the current waveform. This can be displayed and |
exported using WinPM.Net. A value of trip current is shown here. | |
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WL MODBUS Communication and Electronic Accessories • January 2005