Mains filters
Mains filters ensure that electrical interference is reliably attenuated and the supply voltage of devices is protected. Whether as EMC mains filters in industry, as EMI filters for sensitive measurement technology or as RFI filters in audio devices - the right choice reduces interference voltages, improves operational safety and contributes to compliance with standard requirements.
- Protective effect: Attenuation of conducted interference (differential and common mode) to comply with EMC specifications.
- Areas of application: Industrial systems, measurement and testing technology, audio/studio equipment, IT and server environments.
- Types: Built-in filter, housing filter, mains filter socket strip and DIN rail variants.
- Technical characteristics: Rated current, dielectric strength, insertion loss (dB), leakage current and frequency range.
- Certifications & standards: Selection according to relevant EMC and safety standards (e.g. EN, IEC) for the planned application.
When selecting a mains filter, the function and boundary conditions should be considered equally. Important criteria are rated current and rated voltage, the required insertion loss over the relevant frequency range, the permissible leakage current and mechanical connection types. In addition to attenuation, the behaviour in the low frequency range and the minimization of hum or background noise are also relevant for audio applications.
EMC line filters, EMI filters and RFI filters differ mainly in their design and characteristics, not in their underlying function: they minimize conducted interference. Interference filters for industrial environments are often more robust and designed for higher currents and harsher environmental conditions. Filters with low leakage currents and high attenuation values are used for sensitive electronics or laboratory equipment.
Technical notes on integration:
- Observe the polarity and the correct connection types (screw terminals, plug connectors, cable bushings).
- Check leakage current and compatibility with residual current circuit breakers (RCD) for protective measures.
- Allow sufficient space for heat dissipation and accessibility for maintenance.
- Compare insertion loss curves over the frequency range relevant to you instead of just individual characteristic values.
For specific applications - such as audio mains filters, industrial mains filters or compact mains filter socket strips - it is worth matching them to the intended loads and connection conditions. Also pay attention to the manufacturer's information on test values and possible additional functions such as overvoltage protection or integrated fuses.
