The insert frames (7) of a plan sifter have electrically conductive metal parts (15) which are adjacent to the screen fabrics (8) and are connected to a common earth contact (17) of the vibratable housing (1) for discharging static charges from the screen fabrics (8). Freely movable screen cleaners (13) inserted between the screen fabric (8) and a metal support mesh (9) of each insert frame (7) may also be electrically conductive to receive the static charge from the screen fabric (8) and discharge it to the earth contact (17), via the support mesh (9). <IMAGE>
