Power supply voltage indicator SWN 3F is intended for signalling the presence of voltage in a three-phase network. It is mounted on a TS 35 rail.
Each phase corresponds to one LED.
In the case of phase loss, the neon lamp associated with it will turn off. At lower voltage, the lamp glows fainter and turns off completely as voltage goes out.
Applications: low-voltage installations, intended for automation and control systems.