Supressing Electromagnetic penetrations

Posted on Posted in main

 A case for review: Keko Varicon has received a DC motor without any electromagnetic interference (EMI) protective components and was asked to select the most appropriate EMI protection solution for the particular motor. The EMI emissions were out of limits and therefore a component that would suppress EMI was needed. 

Keko Varicon has developed a component that comprises both, capacitor and varistor in the same component thus eliminating a need for two separate components (capacitor & varistor). These dual components(MV & OV series) suppress all DC motor emissions: RE, CE and TE.

Emission tests were performed on the same DC motor again but this time different OV components were used on a brush card of the DC motor. The OV component that suppressed EMI the most was selected as an optimal protective component for this particular DC motor. 


DC motors are used in many automotive and other applications generate substantial amount of electromagnetic noise which can interfere with other electronic systems and consequently compromise their functions. According to various regulations the EMI, also called radio-frequency interference (RFI), must be suppressed below alowable limits.

The emissions of the DC motor with selected OV component were below the allowed limits and DC motor was approved for the use in the automotive application.