PQube User Manual 2.1
Page 49 of 113
Current Distortion (TDD)
Total Demand Distortion (TDD) is a measure of the harmonic distortion of the current your PQube
is monitoring. Instead of comparing the amount of harmonics to the amount of the fundamental
(the method used in THD), TDD compares the amount of current harmonics to the total available
current. You can change the total current used for the calculation by changing the
TDD_Available_Current_in_Amps setting in your Setup.ini file on your SD card. See Standard IEEE 519 for
a full explanation of TDD.
Current Unbalance
Current unbalance is a measurement of the difference in the magnitude voltages in a three-phase
system. Your PQube measures the unbalance of the current waveform using the definition from
ANSI C84.1. This measurement is disabled if the power system being monitored is not three-phase.
Power
Your PQube makes true power readings, correctly handling harmonics (distorted voltages and
distorted currents). Your PQube measures watts, VA, and tPF. “VA” is apparent power, the product
of the RMS voltage times the RMS current. Your PQube correctly calculates VA and Power for all
power configurations, including delta configurations, for which it creates a digital metering neutral.
“tPF” is true power factor, the ratio of watts to volt-amps. (This is different from dPF, which is the
cosine of the angle between the voltage fundamental and the current fundamental.) VAR’s are
calculated using the (default) Budeanu algorithm and Fundamental algorithm. Fundamental VARs
are calculated based on 10/12 cycle data, and these measurements are not gapless.
Energy
Your PQube measures the amount of energy you have used (both energy - Wh, apparent energy –
VAh, and accumulated VARs – VAR-h). Your PQube will accumulate energy until you reset the
counter. You can reset the energy reading using the display on your PQube (go to the Energy
screen in the Meter section and hold down the action button for 3 seconds).
Carbon
Your PQube uses a patent pending method to calculate the amount of CO
2
produced by the energy
consumption monitored. In order to use this feature you will need to determine the amount of
carbon produced by the different type of power your local utility uses, as well as the mixture of the
different types. Once you have this information, you can configure the [Carbon_Intensity] and
[Power_Generation_Breakdown] sections of the Setup.ini file on your SD card.
Temperature and Humidity
Optionally, you can plug one or two TH1 temperature-humidity
probes into your PQube. The probes may be located at your PQube,
or they may be extended up to 20 meters from your PQube with any
2.5mm stereo audio cable. Choose between degrees Celsius or
Fahrenheit in your Setup.ini file.
All data flow to and from the temperature-humidity probe is digital,
which reduces noise issues. The temperature-humidity probes are
electrically isolated from your PQube. This arrangement eliminates
ground loop issues.
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