PQube User Manual 2.1
Page 50 of 113
PQube Recordings
Event and Snapshot Recordings
When your PQube detects an event, it records information about the event to its SD card. You can
remove the SD card to look at this data, look at the recent events screen of the display, or (if you
have an optional ETH1 Ethernet module) you can get emails about the event or even look at the
event using your web browser. However you look at the event, the data is always the same.
Interpreting Event and Snapshot Recordings
PQube Event and Snapshot recordings contain the details of the event recorded (for example,
Voltage Dip recordings include the precise start time of the event, the duration of the event, and
the magnitude of the event)
Most events also include the waveforms for the beginning and end of the event, as well as the RMS
measurements for the beginning and end of the event. If multiple events occur very close together
(within about 30 seconds of each other) your PQube will record all events, but will only store
waveform and RMS data for the first event. This is because your PQube is still clearing the space
that it requires to record the information. It is important to note that, as long as your PQube is
running, it is almost impossible for it to miss an event (your PQube can miss an event if more than
4 events of any one type occur within 4 seconds of each other).
During an event, your PQube will always be sampling the voltage at 256 samples per cycle. You can
change the number of samples per cycle written to an event recording (256, 128, 64, or 32 samples
per cycle) by changing the Recorded_Samples_Per_Cycle setting in the Setup.ini file on your SD card.
Why would I want fewer samples per cycle in my recordings?
Your PQube Records 1024 samples at the beginning of an event and 1024 samples at the
end of an event. If your PQube is configured to record at 256 samples per cycle, it will
record 4 cycles at the beginning and 4 cycles at the end of the event (1024/256=4). If you
set the recording rate lower, you get a longer recording (with fewer points per cycle).
For example, if you choose 64 samples per cycle, your PQube will continue to sample at
256 samples per cycle, but the output recording will be written at 64 samples per cycle.
Your Event recordings will have 16 cycles at the beginning and 16 cycles at the end of the
event (1024/64=16).
Of course, you always get many cycles of RMS values: 10 seconds of data at 50Hz or 8.5
seconds of data at 60Hz, regardless of the number of samples per cycle you choose to
record. The RMS is the 1-cycle average, refreshed every half cycle.
NEW for Firmware 2.0: Instead of recording 1024 samples at the beginning of event, and
1024 samples at the end of event, you can now record 2048 samples at the beginning of
event in exchange for discarding the end-of-event data.
For RMS measurements, instead of measuring the 1-cycle RMS refreshed every half cycle,
you can now choose to record the RMS every 1 cycle. This doubles your RMS graphs from
10 seconds to 20 seconds at 50Hz, and from 8.5 seconds to 17 seconds at 60 Hz.
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