FIELD: electricity.
SUBSTANCE: invention is related to grounding of electronic circuit in instrument that belongs to low-voltage system with maximum AC voltage of 1000 V or maximum DC voltage of 1500 V, in which instrument is energised with voltage of power grid or is connected to power grid by means of high impedance connection, and also to overvoltage protection of interface between this electronic circuit and circuit SELV (safe low-volt voltage). Neutral point (COM) of electronic instrument is connected to protective earthing (PE) via at least one safety fuse of breakdown overvoltage. Rated voltage of breakdown (Ub) of overvoltage safety fuse is higher than voltage in it in normal mode of operation, but is less than minimum electric strength (Uc) of components that create interface between electronic instrument and SELV circuit (safe low-volt voltage).
EFFECT: improved reliability of overvoltage protection.
8 cl, 3 dwg
