PQZIP Recording - Principle
The Portable BLACKBOX is able to continuously record & store all the electrical waveforms, all the
time, in the case of the G4500 for more than a year, with no gaps in the data. The innovation
behind this capability is the PQZIP compression technology. The patented PQZIP enables you to
store up to a 1000 times more information than typical formats, allowing for storage of complete &
precise data over extended periods of time.
FLOW DIAGRAM:
DEFINITIONS:
Recording & Measurement: The waveforms are being sampled at 1024 samples per cycle
resolution for voltages and 256 samples per cycle resolution for currents.
ADC: Voltages and currents are being converted & scaled to achieve a maximum resolution
using the following Analog to Digital Conversion process.
Data Buffer: The digital waveform data is buffered resulting in 512 spectral components
(harmonics) per cycle for voltages and 128 for currents.
Compression Algorithm: Every harmonic component is being analyzed and compressed
individually. Zero value components are skipped. No-zero harmonic components are
evaluated over time & only changes in a value or angle are processed. Resulting in storage of
complete & precise data over extended periods of time.
Compressed Data Files: The compressed harmonic data is being organized in blocks of 5
minutes or more, consisting of concurrent cycles and being stored along with the measured
frequency of every cycle and reference time stamps into a PQZIP file residing on the onboard
flash memory. The typical compression ratio expected as a ratio between incoming data
volume on block 3 and the data being stored is 1000:1.
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