Novatech Bitronics PowerPlex II - Harmonic Measurements

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ML0047 December 1, 2017 Copyright 2017 Bitronics, LLC
5.10.4 Demand Resets
The demand values are reset in 3 groups: current, voltage, and power. This can be
accomplished via the front display or from a web browser.
5.10.5 Demand Interval
The PPX II uses 900 seconds (15 minutes) as the default demand interval for current.
The default for average volts and average power measurements is 60 seconds. Three
separate, independent demand intervals may be set for current, voltage, and power.
The range of demand intervals is 10 to 9999 seconds. These settings can be
accomplished by using the front display or web server setup.
5.11 Harmonic Measurements
All harmonic and harmonic related measurements are calculated every cycle. In the
following sections, Harmonic 0 indicates DC, Harmonic 1 indicates the fundamental,
and Harmonic N is the nth multiple of the fundamental.
5.11.1 Voltage Distortion (THD)
Voltage Harmonic Distortion is measured by phase in
several different ways. The equation for Total Harmonic
Distortion (THD) is given in Equation 1. Note the
denominator is the fundamental magnitude.
5.11.2 Current Distortion (THD and TDD)
Current Harmonic Distortion is measured by phase in
several different ways. The first method is Total Harmonic
Distortion (THD). The equation for THD is given in Equation
2. Note the denominator is the fundamental magnitude.
Alternatively, Current Harmonic Distortion can be
measured as Demand Distortion, as defined by
IEEE-519/519A. Demand Distortion differs from traditional
Harmonic Distortion in that the denominator
of the distortion equation is a fixed value. This fixed
denominator value is defined as the average monthly
63
2
2
1
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h
h
I
THD
I
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63
2
2
1
%100%
h
h
V
THD
V
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2
2
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h
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I
TDD
I
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Equation 1 - Voltage THD
Equation 2 - Current THD
Equation 3 - Current TDD