Interference suppression filters and mains filters limit pulse-like, high-frequency interference voltages caused by mechanical or electronically triggered switching operations. If interference voltages are not limited, they spread via the cable network and electrically conductive connections. This can result in data errors, uncontrolled functions, and system crashes. Mains filters ensure an EMC-compliant power supply by limiting interference voltages.
Interference suppression filters with integrated surge protection perform two tasks: they absorb transient overvoltages and also limit high-frequency interference voltages.
Various designs are available:
SFP DIN rail module
TERMITRAB terminal block
Interference suppression filters or mains filters with a dedicated filter circuit protect against both symmetrical and asymmetrical disturbance variables.
NEF DIN rail module
TERMITRAB terminal blocks with integrated interference suppression capacitor are suitable for applications where asymmetrical protection is sufficient.
Filtering of symmetrical disturbance variables X
Interference voltages between the phase and neutral conductor are filtered.
Filtering of asymmetrical disturbance variables Y1 Y2
The respective negative phase-sequence grounded interference voltages from the phase conductor to PE and from the neutral conductor to PE are filtered.
An attenuation characteristic curve diagram illustrates the effective operating range of mains filters. The relevant frequency-dependent attenuation can be read according to the symmetrical or asymmetrical filter circuit.