power filters

The basics of harmonic filters you should understand

It is true that the quality of power has continuously deteriorated because the major increase in the number of electronic equipment that are connected to mains AC supply, leading to an increase in nonlinear loads. These nonlinear load draw a lot of power from the supply voltage leading to distortion that is caused by harmonic currents. What distorted currents do is that they cause the various pieces of equipment that are connected to the power supply not to work properly. Conductors that make part of the equipment usually overheat and cause a decrease in the level of efficiency of the equipment together with their lifespan.

To avoid problems that result from harmonic currents, passive LC power filters are usually introduced. The work of these filters is to remove the harmonic currents that nonlinear loads cause.

et us take a look at harmonic currents
Simply put, harmonic is a constituent of a periodic wave. Harmonics are generated as byproducts of modern electronics and they happen very frequently these days. Harmonics happen when there is a huge number of electronic devices such as variable frequency drives, uninterruptible power supplies, and personal computers among other devices that use solid state power switching supplies in the process of converting AC power to DC power.

The harmonics that are experienced in a power circuit result because nonlinear loads draw current in abrupt short pulses as opposed to a smooth sinusoidal manner. What happens when these harmonics are generated is that they travel to the load and back into the power source, leading to serious interference, which can be very annoying when they occur in a circuit. The only solution is usually to remove the harmonics.

Difference between Linear and Non-Linear Loads
The terms nonlinear and linear are used in the definition of the relationship that exists between the voltage waveform and the current. When there is a linear relationship between the voltage and the current, the load is referred to as linear. On the other hand, if the current relationship to the voltage is discontinuous, the load is referred to as nonlinear. That means that the current does not correspond to the voltage that is applied. When we talk of harmonic filters, we are referring to the type of filters that are applied in a circuit to eliminate harmonic distortion that results from nonlinear loads.

Harmonic filters
Like stated above, harmonic filters remove harmonic distortion resulting from nonlinear loads. The design of these filters allows them to attenuate or remove the dangerous effects that harmonic currents cause in a power distribution system. Depending on the design of the filter, it can trap the harmonic currents using a series of resistors, coils, and capacitors and damp them into the ground. A filter usually contains several of coils, resistors, and capacitors that are meant to compensate a specific frequency or multiple frequencies.

It is important to understand that there are other methods other than the use of filters that can be used to remove harmonic currents from circuits, but filters are preferred because they present the best solution.