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DETUNING REACTORS
The growing use of power electronic devices is causing an L 1 L 2 L 3
increasing level of harmonic distortion in the electrical sys-
tem which very often leads to problems with capacitor in-
stallations. This is the reason why more and more energy
suppliers demand the installation of detuned capacitors.
A detuned capacitor performs the function of power factor
improvement whilst preventing any amplification of harmonic
currents and voltages caused by resonance between capaci-
tors and inductances in the electrical system.
By adding an appropriately rated series reactor to the power
capacitor, both elements form a resonating circuit with
its resonant frequency below the lowest order har-
monic in the system (usually the 5th). All frequencies above
this resonant frequency now see this circuit as inductive
hence eliminating the possibility of dangerous resonances
being set up between the capacitors and system inductances
(provided the reactor has been dimensioned properly).
It has to be ensured, however, that non-detuned capacitors
and capacitors with detuning reactors are never operated in
the same mains. Such combination may cause unforeseeable
interactions and equalising currents leading to damage and
destruction of capacitors, reactors, and other components.
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