Application note
AN0004Polarized vs Bidirectional Switching
How magnetic arc blow-out orientation determines whether a contactor breaks current in one direction or both.
Summary
All high-voltage DC contactors carry current in both directions when closed, but their ability to interrupt current under load depends on internal design, most notably the orientation of the magnetic arc blow-out system. This application note explains the difference between polarized and bidirectional contactors, focusing on switching behavior, arc control, and application-driven selection. Polarized contactors are optimized to break current flowing in one direction and can interrupt higher current levels, while bidirectional contactors break in either direction at lower levels, so engineers must analyze application requirements to choose the right type. It also covers how internal permanent magnets direct arc motion and how that influences electrical cycle life and interruption capability.
