Protective chokes - Efektivní ztráty [W] - 153
The shielding inductors, connected with capacitors, form a series resonant circuit (usually 189 Hz) that prevents unwanted resonance and also acts as a broadband filter. This protects the individual components of the compensation system from overload. The dampers are characterized by high linearity and low losses. In most cases, it is advisable to use chokes when the THDu voltage distortion is greater than 3%.
Many electrical devices, equipment and systems require electromagnetic fields to function.This necessity leads to the consumption of reactive power, which provides the basic function but not the active power. This means that the transmission and distribution system is burdened with reactive power, which is not economically efficient and therefore polluters of the grid are penalized by the distribution companies. The solution is to use compensation devices that supply the necessary reactive power from the capacitors directly to the equipment, thus removing the unwanted load on the grid. Systems containing higher harmonics can be susceptible to the creation of a resonant circuit between the capacitors and the transformer inductance and can cause damage to the power grid.
The solution is to use gated compensation, which combines capacitors with gated inductors. Such a gated system shifts the resonant frequency to lower values (below the first harmonic) where there are no harmonics, so that safe operation of the network is ensured. In addition, this circuit has a certain tuning frequency that allows to filter harmonic currents and thus reduce the level of distortion of the network. In order to achieve the desired tuning frequency, the gate inductors and their inductance must be selected to exactly match the capacitance of the capacitor. Since the capacitor is connected in series with the gate inductor, it must be taken into account that it is loaded with a higher voltage than the mains voltage.