Filter reactors are used in conjunction with capacitor banks to form series tuned harmonic filter circuits, or in conjunction with capacitor banks and resistors to form broad-band harmonic filter circuits. When specifying filter reactors, the magnitudes of fundamental and harmonic frequency current should be indicated. If the inductance adjustment for fine tuning is required, the required tapping range and tolerances must also be specified. Many filter application require a Q factor that is very much lower than the natural Q of the reactor. This is often achieved by connecting a resistor in the circuit
Capacitor inrush current limiting reactorsCurrent limiting reactors are used generally in series with the capacitor bank either for limiting the capacitor inrush current. The rating varies from 0.2% to 13% for various applications. They are used in line side or neutral side depending on the application involved and hence the short circuit current withstand ability of the reactor is designed. They are primarily used in Power Factor Correction Systems and applications where capacitor discharge current needs to be limited.
The detuned reactors are designed to protect the capacitors against harmonics and avoid parallel resonance and amplification of harmonics flowing on the network. The connection of these reactors in series with capacitors causes a shift of the resonance frequency of the circuit composed by feeding transformer-reactors- capacitors so that the resulting self-resonance frequency is well below the line harmonics
The windings are made by copper or aluminum wire (insulated by class H double-layer enamel or by double Nomex tape), protected by a vacuum and pressure impregnation (VPI) by solvent less polyester resin, followed by thermosetting in oven. The number and position of air gaps are selected in order to minimize losses in magnetic core and windings. Limbs, yokes and air-gaps are blocked by adhesives and pressing elements designed to reduce acoustic noise and designed with natural air cooling
The blocking factor p% is expressed by the ratio between inductive reactance and capacitive reactance it corresponds to the increase of voltage applied to capacitors, with respect to line voltage, due to circulation of capacitive current in the reactor. It is related to the resonance frequency (fris) of the system by the formula:
fris= 50 x √ 100
A line reactor acts as a current-limiting device. it also filters the waveform and attenuates harmonics, electrical noise and transients associated with the system. Reactors are installed in HVAC equipment, pumping equipment, machine tools, elevators, printing presses, UPS equipment, computer mainframes, robotics equipment, ski lifts, wind generators, electric cars, cranes, trams, and many other types of equipment, to extend the service life of the VFD and motor. line reactors are connected on the line side of a VFD. Harmonic compensated line reactors are specially designed to handle the waveform's harmonic content. By inserting inductive reactance into the circuit, which is a high impedance to harmonic frequencies, line reactors reduce the amount of harmonics produced by a VFD system. For harmonic reduction purposes, you typically apply 5% impedance line reactors to the input of motor drives 20 hp and higher. This reduces input harmonics to 35% total harmonic current distortion (THID) or less and minimizes the effects of harmonics on motors and other devices powered off the same electrical system.