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4.15.4 High-resolution Waveform Logging
The high-resolution waveform logging partition is meant to record waveforms
sampled at high frequency of 128 samples per cycle allowing to perform Fourier
analysis and harmonic distortion measurements with high resolution up to 63rd
harmonic.
Waveform recording can run on any trigger. Recorded waveforms are not captured
at the time the event triggers recording. Because the high-frequency sampling runs
periodically, sampled waveforms are captured in the buffer whenever they were
sampled, and recorded into the log partition at the time the setpoint runs waveform
recorder. Therefore, the high-resolution waveform recording may not provide
synchronization between the event that caused the trigger to operate and the recorded
waveforms. Recorded waveforms might provide both pre-event and post-event data,
or might not.
Each waveform log record stores at once 6 waveforms × 4 cycles (voltage and
current on all three phases) sampled at a rate of 128 samples per cycle. The voltage
and current waveforms on each separate phase are always recorded synchronously
and can be used for power harmonic measurements. Waveforms corresponding to
different phases are not synchronized, and might be sampled with up to 0.5 second
interim.
Each record is provided with date and time stamp at a 1 second resolution, and
stores reference fundamental frequency, total harmonic distortion and real-time
RMS value for each input. The partition' s logging ability and factory setting are the
same as for the high-speed waveform log partition (see above).
4.16 Monitoring And Recording Disturbances
4.16.1 Disturbance Analysis
Voltage disturbance monitoring is used to capture and record the disturbed
waveforms for later disturbance analysis on a PC. The PM295 stores any
disturbance in voltage on any phase that exceeds a user-defined threshold. The user
needs only to define the maximum voltage deviation allowed. The recorded
waveforms then can be uploaded to a master PC and observed with the PAS295
software.
The PM295 provides the capture and recording of various types of disturbances
with a duration from one millisecond and up to tens seconds - transients, outages,
sags, surges and deviations in voltage levels.
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Operation Techniques
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