Harmonics
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Harmonics are voltages and currents with frequencies that are different from a 50 Hz or 60 Hz
power supply frequency.
Harmonics result from the operation of electrical loads with non-linear voltage-current
characteristics.
They are mainly caused by loads operated with modern electronic devices, such as converters,
electrical drives, welding machines and uninterruptible power supplies (UPS).
Ensure that the current through the capacitor doesn’t exceed the limits given in the specific data
sheets.
Ensure that the voltage doesn’t exceed 1.1 VR and the peak voltage doesn’t exceed 1.6 VR. Use
a true rms and peak voltmeter or oscilloscope to check it.
Note
Only power capacitors with reactors – namely de-tuned capacitor banks – should be used in
applications with harmonic distortion. Depending on the chosen series resonance frequency, a
part of the harmonic current will be absorbed by the power capacitor. The rest of the harmonic
current will flow into the grid. The use of power capacitors with reactors reduces harmonic
distortion and minimizes the disturbing effects on operation of other loads.
Note
Avoid resonance conditions
The most important reason for installing de-tuned capacitor banks is to avoid resonance
conditions. Resonance conditions may multiply existing harmonics, create power quality
problems and damage distribution equipment.
Occurrences of resonance should by all means be avoided by appropriate application design.
Total RMS capacitor current (incl. fundamental and harmonic currents) specified in the technical
data of the specific series must never be exceeded.
Installation and maintenance instructions for Power Factor Correction (PFC) capacitors
Installation Manual, 05/2022, L1V30884033A
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