118
Power Quality Analyzer PowerPad
®
IV Model 8345
20. APPENDICES
This section has the formulas used to calculate the different parameters and the
definitions for abbreviations.
The formulas comply with standard IEC 61000-4-30, edition 3.0, for Class A
instruments and comply with IEEE 1459, 2010 edition, for the power formulas.
20.1 NOTATION
Notation
Description
Y
Represents V, U, or I
L
Number of the phase or of the channel
n
Instantaneous sample index
h
Subgroup order of the harmonic or of the interharmonic
M
Total number of samples in the duration considered
N
Number of cycles
Y
L
(n)
Instantaneous value of the channel L sample having index n
Y
sghL
(h)
RMS value of order h’s sub-group harmonic on channel L,
Voltage/Current
= square root of the sum of the squares of the RMS values of a
harmonic and of the two spectral components directly adjacent to it
Y
sghL
(h)
RMS value of order h’s centred interharmonic subgroup on channel L,
Voltage/Current
= RMS value of all spectral components between two consecutive
harmonic frequencies, not including the spectral components directly
adjacent to the harmonic frequencies
I
hL
(h)
RMS current of the harmonic of order h on channel L
Most measured quantities can be calculated from aggregations of different
durations:
■
1 cycle (= 1 period = 1/frequency)
■
10/12 cycles (10 cycles for 50 Hz, 12 cycles for 60 Hz)
■
150/180 cycles (150 cycles for 50 Hz, 180 cycles for 60 Hz)
■
10 min