Mains Filter

Common mode chokes with dual winding chambers are charatcerized by a higher attenuation maximum compared to those with a single winding chamber. At the same time, this attenuation maximum is shifted to higher frequencies.

By choosing the right core material for common mode chokes, the desired attenuation curve depending on the frequency can be chosen. While manganese-zinc has its attenuation maximum at lower frequencies, it is higher for nickel-zinc. Nanocrystalline core material and the combination of manganese-zinc with nickel-zinc exhibit broader attenuation behavior. 

Filter chokes can be operated at 100% of their rated current up to ambient temperatures of approximately 110°C. Beyond this, the curve drops steeply. At 140°C only about 40% of the rated current is permissible.

Bei den Leitungsfiltern lassen sich verschiedene Stufen unterscheiden. Einstufige Filter (single stage) bieten eine Dämpfung von bis zu 75 bis 80 dB. Beim verbesserten einstufigen Filter (single stage advanced) sorgt ein zusätzlicher x-Kondensator für eine bessere Unterdrückung des Gegentaktrauschens. Die höchste Gleich- und Gegentaktdämpfung bietet der zweistufige Filter (two stage) mit zusätzlicher Gleichtaktdrossel und weiterem x-Kondensator.

Disk varistors are used in surge protection. It is important that the clamping voltage Vclamp is sufficiently low so that sensitive electronic components in the circuit do not experience voltage spikes. Once the clamping voltage is reached, the voltage hardly increases further; it is "clamped". Steeply rising currents are diverted with low resistance. If the current exceeds Ipeak, it can lead to the destruction of the disk varistor. The maximum operating voltage is significantly lower than the clamping voltage.

In surge protection, a sensitive electronic component (Load) is protected by a parallel discharge path (VDR), which becomes conductive when the breakdown voltage of the protective element (VDR) is reached. In this way, the surge (Transient) does not reach the sensitive load (Load) and is "clamped" to the clamping voltage (Clamping Voltage).

In the suppression of EMI signals, capacitors, known as X and Y capacitors, are also used. Depending on the frequency, the impedance of a capacitor varies by several orders of magnitude, as can be seen in the logarithmic visualization. Regardless of the capacitors's capacitance, the impedance curves are qualitatively similar. However, the capacitances do influence the respective frequencies of the impedance minima.

In the suppression of EMI noise signals, capacitors are used as so-called X and Y capacitors. On the left side of the image, voltage ripples from the AC power source are visible, which prevent a clean signal waveform. On the right, a clean sine wave is shown, which has been smoothed after filtering the voltage ripples of the AC power source with interference suppression capacitors.

Harsh environments with high temperatures and high humidity can degrade the dielectric layers in capacitors, thereby reducing their capacitance. The table shows the test classes from 1 to 6 and under which conditions - duration, temperature, and relative humidity - the capacitors were tested at nominal voltage.