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ITGlossary · Power quality
RFI — Radio Frequency Interference
A subset of EMI: high-frequency noise from electronic equipment that can disturb radio, Wi-Fi and other devices.
Technical level:Intermediate
Any electronic device that switches current rapidly, such as switch-mode power supplies, inverters, variable-speed drives and LED lighting, emits high-frequency noise. When that noise falls within the radio frequency range, it is called RFI. It travels either along the power cables or as radiation.
RFI can degrade Wi-Fi, radio and TV reception, cause errors in measurement and audio systems, or affect sensitive medical equipment. This is why UPS units, inverters and power strips include EMI/RFI filters and must meet the electromagnetic compatibility (EMC) limits required for CE marking.
A practical tip: keep power cables separate from signal and network cables, and use ferrite cores where needed.
Related terms
- Noise (Electrical)Unwanted high-frequency disturbances on the supply voltage, e.g. from motors or power supplies, which UPS systems and line conditioners filter out.
- Electromagnetic Interference (EMI)Unwanted electrical noise or interference that can disrupt electronic equipment operation.
- Automatic Voltage Regulator (AVR)A device that automatically maintains a constant voltage level to protect electrical equipment from fluctuations.
- Power ConditioningTechniques such as EMI/RFI filtering, surge protection and AVR that correct voltage problems before they reach the load.
- Voltage SpikeA momentary, very high voltage rise lasting microseconds, e.g. from lightning or load switching, that can damage equipment.
- ATS (Automatic Transfer Switch)A device that automatically moves the load from the grid to a generator during an outage and back again when grid power returns.