DEVICE FOR PROTECTION OF ELECTRICAL CONSUMERS FROM OVERVOLTAGE IN SINGLE-PHASE AC NETWORKS Russian patent published in 2017 - IPC H02H3/20 

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and is intended for equipment protection against excessive voltage. Core of invention is that elements limiting overvoltage (varistors) are used together with the RCD and are connected in such a way that currents occurring through them in case of overvoltage are differential for the RCD and result in its triggering (switch-off) if the limitation current exceeds a threshold for the selected RCD and the exposure lasts longer than the RCD triggering time. So, typical time of operation of an electromechanical RCD of AC type is within the range of 25–40 msec, most frequently for people protection against electric shock and for protection against fires RCDs are used with the differential current of triggering of 10 and 30 mA, herewith from the moment of overvoltage start till the RCD switch-off the peak dissipated by the varistor power is within allowable limits for most varistors structurally made as a disc with the diameter of 20 mm, and the average power dissipation is of fractional Watt.

EFFECT: technical result is improvement of reliability, durability of electric consumers, new useful properties in mass-produced residual current devices (RCDs) without interference into their structure and change of their main parameters.

1 cl, 2 dwg