EMI / Mains Filtering
EMI Mains Filtering indicates whether a power supply includes filtering intended to reduce unwanted electromagnetic interference on the mains connection.
The filter targets unwanted high-frequency electrical content rather than the intended mains power waveform. Its effect depends on frequency and the complete circuit. A feature entry does not quantify attenuation, identify every filtered path or establish immunity to all interference.
EMI / Mains Filtering — Power Supply
The filter is one part of the supply’s design. Output regulation, rectification, grounding and the powered device also affect the final result. A filtering claim alone does not show the residual noise at the DC output or prove that an existing audible problem will disappear.
Check any stated filtering range and measurement conditions when comparing supplies. Keep this feature separate from surge protection and voltage regulation, which address different electrical behaviours. Use the supply as intended without modifying mains wiring or protective earth.