Distortion Factor Calculation (Df); K Factor - AEMC 8335 User Manual

Distortion Factor Calculation (DF)

Two global values giving the relative quantity of harmonics are computed: the THD
in proportion to the fundamental and the DF in proportion to the RMS value.
50
∑
Vharm
[]
n 2
Vthd i =
=
Vharm
50
1
∑
Vharm
2
[]
n 2
Vdf i =
=
Vrms
Multiplying the voltage harmonic factor with the current harmonics factor gives the
power harmonic factor. Differentiating voltage harmonic phase angle with current
harmonic phase angle gives power harmonic phase angle.
VAharm[3][51] , VAph[3][51]

K Factor

[]
Akf i
96
2
[][ ]
i n
[]
, Uthd i
=
[][ ]
1
i
[][ ] 2
i n
[]
, Udf i
=
[]
i
n=50
∑
n Aharm
2
n = 1
=
n=50
[][ ]
∑
Aharm i
n = 1
50
2
[][ ]
∑
Uharm i n
n 2
=
[][ ]
1
Uharm i
50
1
[][ ]
∑
Uharm i n
2
n 2
=
[]
Urms i
[][ ]
2
i n
K factor for the i + 1 phase
2
n
Power Quality Analyzer Model 8335
50
∑
Aharm
[]
n 2
, Athd i =
=
Aharm
50
1
2
∑
2
[]
n 2
, Adf i =
=
2
[][ ]
i n
[][ ]
1
i
[][ ] 2
Aharm i n
[]
Arms i