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11.
PQ Configuration
Page 52 from 69
11.10 Total harmonic distortion THD, harmonics, interharmonics
The distortion of the mains voltage is described with the help of harmonics and interharmonics.
Harmonics are integer multiples of the fundamental and are characterized by an order h --> e.g. U
for the
h3
third order harmonic (in the 50 Hz network this would be 150 Hz).
Interharmonic voltages are non-integer multiples of the fundamental.
The total harmonic distortion THD (also known as distortion factor) is calculated, in simplified terms, from the sum of the root mean
square of the harmonic to fundamental ratios up to a certain order h.
Limits
In addition to the maximum permitted for each harmonic and interharmonic, a time period can be defined in which the limits must be
observed before a violation occurs.
The maximum is given as a % value to the rms value of the fundamental (50 Hz).
In addition, the highest order up to which the individual harmonics are included in the calculation of the THD can be defined.
11.11 Mains signalling voltages
Power supply companies often use their network for communication purposes.
Mains signalling voltages, so-called ripple control signals, are used for this purpose.
The frequency of the mains signalling voltage is the carrier frequency of the modulated signal.
Parameter
In addition to the frequency of the mains signalling voltage itself, the duration and trigger threshold from which a mains signalling
voltage is detected can be set individually. The duration describes the time window in which monitoring starts after the trigger threshold
has been exceeded.
These parameters are defined under Device settings, as they apply to both the standard and the individual limit value.
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