Phase Line Filter Design

Protecting the power grid from unwanted interference caused by connected devices often necessitates the use of a mains filter to suppress interference signals produced by these loads. This application note outlines the necessary steps for designing an appropriately dimensioned mains filter.

To address potential interference, the note details the use of simulations and measurements to evaluate both single-stage and two-stage mains filters. It further explores the characteristics of different core materials used in current-compensated chokes. Key aspects covered include the distinctions between common mode and differential mode interference, as well as the function of Line Impedance Stabilization Networks (LISN).

The note provides guidance on calculating and implementing both one-stage and two-stage line filters, including advice on circuit simulation and practical realization. It also includes instructions for conducting comparative measurements in an EMC chamber to ensure the filter's effectiveness. Essential calculations related to varistor, leakage current, and discharge resistance are discussed, along with best practices for mains filter layout and component selection. Lastly, the note delves into the selection of core materials for current-compensated chokes, highlighting their impact on filter performance. This comprehensive approach ensures the development of a filter that effectively mitigates unwanted interference and maintains power grid integrity.