#AF FILTER PDF INSTALL#
#AF FILTER PDF SERIES#

#AF FILTER PDF SERIES#

Passive, where a series of inductors and capacitors try to filter the high frequency components, preventing them reaching the mains. There are two types of harmonic filter: 1. The ‘C’-type filter attenuates low order non-characteristic harmonics, where the losses in a second-order filter would be uneconomically high. In the ‘C’-type damped filter a capacitor C2 is connected in series with the inductor L and the fundamental frequency losses are minimised by tuning C2 to resonate with the inductor at fundamental frequency. In the third-order broadband damped filter the fundamental frequency losses in the resistor are reduced by the use of a capacitor C2 in series with the resistor. The losses can be reduced significantly by the use of an additional capacitor as shown in Figure 32.38(c) and 32.38(d). The damped broadband filter shown in Figure 32.38( b) requires a significantly higher var rating than a corresponding sharply tuned filter to provide the same harmonic absorption at a given frequency, but Figure 32.40 shows that damping and filtering is provided over a range of harmonic frequences.ĭamped filters must have a higher var rating than the corresponding tuned filters to achieve same filtering performance, and their losses are higher. Alternative types of double-tuned harmonic filters They are used in specific applications to take advantage of the benefits of both filters.įigure 32.39. Hybrid filters are combinations of active and passive filters.

#AF FILTER PDF INSTALL#

They are, however, more expensive to install than passive filters. Ther efore, active filters can be considered for more complicated and critical systems because they have a better capability to act in response to drastic disturbances. Active filters have the advantage to respond to dynamic changes in the electrical distribution systems ( Fuchs and Masoum, 2008). Specifically, active filters correct for the distorted sinusoidal current waves to effectively eliminate harmonics. 2.Īctive filters rely on active power conditioning electronic devices to compensate for unfavorable harmonic currents. Some potential issues can occur with passive systems if not properly selected resulting in resonance circuits parallel with power source leading to worse power quality conditions.

They are tuned to provide a low impedance path for specific currents with undesirable harmonic frequencies. Passive filters are made up of reactive components like capacitors, inductors, and resistors. There are three main classifications of filters: (1) passive, (2) active, and (3) hybrid filters: 1. Specifically, harmonic filters are designed to have low impedances to ensure that the harmonic currents are flowing between the loads and the filters, rather than reaching the power source and the other components of the electrical power generation and distribution systems. Power harmonic filters are mainly used to either block harmonic currents from flowing through electrical power distribution systems or locally isolate and cancel them ( Fuchs and Masoum, 2008). Because damped filters have significantly higher resistance than single- or double-tuned filters, they are usually not used to filter harmonics near the power frequency so that filter losses can be maintained at low values. In general, damped filters are tuned in between the corresponding pairs of harmonics (11th and 13th, 17th and 19th, etc.) to provide the maximum harmonic reduction at those frequencies while continuing to serve as a (not quite as effective) filter bank for frequencies higher than the tuned frequency. Because most capacitors have a negative temperature coefficient (capacitance decreases and therefore tuned frequency increases with temperature), tuning slightly lower than the desired frequency is desirable.ĭamped filters are typically used to control higher-order harmonics as a group. 2.Īll electrical components have some non-zero temperature coefficient, and capacitors are the most temperature sensitive component in a tuned filter. This action can quickly overload the filter. The reasons for this practice are as follows: 1.įor a low-resistance series resonance filter that is exactly tuned to a harmonic frequency, the filter bank will act as a sink to all harmonics (at the tuned frequency) in the power system, regardless of their source(s). In most cases, it is common to tune single-tuned filter banks to slightly below (typically around 5%) the frequency of the harmonic to be removed.

Af filter pdf