EMI filter, what is an emi filter, emi power filter

An EMI filter, or electromagnetic interference filter, is an electronic passive device which is used in order to suppress conducted interference that is present on a signal or power line. EMI filters can be used to suppress interference that is generated by the device or by other equipment in order make a device more immune to electromagnetic interference signals present in the environment.

https://www.futureelectronics.com/c/passives/filters--emi-filters