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©2016 Guangzhou ZHIYUAN Electronics
Date: 2016/12/08
User Manual
V1.00
C
Guangzhou ZHIYUAN Electronics Co., Ltd.
PA5000 Series Power Analyzer Start Guide
6.5.1
Set calculation formulas for apparent power, reactive power and
corrected power
1. Function Introduction
(1) Select calculation formulas for apparent power and reactive power
There are three kinds of power: active power, reactive power and apparent power. Their
formulas are defined as follows (U: voltage RMS; I: current RMS;
φ: voltage and current
phase difference):
Active power P = UIcosφ.
Reactive power Q = UIsinφ.
Apparent power S = UI.
The relationship among the three powers: (apparent power S)
2
= (active power P)
2
+
(reactive power)
2
.
The above defined formula only applies for the sine wave; however, when measuring
the distorted waveform, the measured values of apparent power and reactive power are
different according to the above formula. Therefore, three kinds of calculation formulas
are provided for apparent power and reactive power. Users can select the calculation
formula for apparent power and reactive power from Type1~3 shown in Table 6-2.
Table 6-2: Selectable calculation formulas in each measurement mode
Measurement mode
Calculation formulas of S and Q
TYPE1
TYPE2
TYPE3
Normal measurement
Optional
Optional
Optional
IEC harmonics/Harmonics
Fixed to TYPE3
Waveform calculation
Optional
Optional
Not optional
FFT
Fixed to TYPE2
Voltage fluctuation and flicker
Not supported
Cycle analysis
Fixed to TYPE2
TYPE1
Type1 calculation formula:
Active power of 3P4W:
PΣ = P1 + P2 + P3.
Apparent power of 3P4W:
SΣ = S1 + S2 + S3 (= U1 × I1 + U2 × I2 + U3 × I3).
Reactive power of 3P4W:
QΣ = Q1 + Q2 + Q3.
(=
(U1 × I1)
2
− P1
2
+ (U2 × I2)
2
− P2
2
+ (U3 × I3)
2
− P3
2
)
When the current phase leads the phase of voltage, the Q1, Q2 and Q3 values are
negative, otherwise they are positive.
TYPE2
Type2 calculation formula:
Active power of 3P4W: PΣ = P1 + P2 + P3.
