Fluke 1760 [59/110] Harmonics and interharmonics parameters

Fluke 1760 [59/110] Harmonics and interharmonics parameters
Operation
Methods of Measurement/Formulas 3
3-19
voltages. For 50 Hz or 60 Hz power systems the appropriate filter coefficients are
applied. The classifier consists of 1130 logarithmic classes.
If the option Events, Flicker, and Harmonics of U12…. in the device settings is activated,
the Flicker of the phase-to-phase voltages U12, U23, U31 is recorded.
Harmonics and Interharmonics Parameters
Voltage and Current Harmonics and Interharmonics
Voltage and current harmonics are calculated based on a 10/12 cycle (200ms) averaging
interval. This interval contains exactly 2048 sample values. From these samples 1024
FFT bins (5Hz) are calculated.
The harmonics are then calculated using a gapless harmonic subgroup assessment.
The interharmonics are calculated using a gapless interharmonic centered subgroup
assessment.
Harmonics and interharmonics calculation as per IEC 61000-4-7:2002 section 5.6 (no
smoothing).
THD – (Total Harmonic Distortion)
The calculation utilizes the following formula: Voltage or current respectively.
1
40
2
2
V
V
THD
n
n
=
=
n: order of the harmonic.
V
1
: rms value of the voltage fundamental.
Vn: rms value of the voltage harmonic with order n.
1
40
2
2
I
I
THD
n
n
=
=
n: order of the harmonic.
I
1
: rms value of the current fundamental.
In: rms value of the current harmonic with order n.
TID
TID is the complete interharmonics contents of the signal. It is calculated as per EN
61000-4-7:1993 from all interharmonics spectral bins (absolute values) up to the
harmonic with order 40.
THD ind
THD ind is calculated according to the formula in the norm EN61000-4-7:1993. This
formula is no more part of the actual version of EN 61000-4-7 but has still importance for
applications in networks with inductive loads.

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