ALTERNATING-CURRENT SPARK PROTECTION UNIT Russian patent published in 2015 - IPC H02H3/38 

FIELD: electricity.

SUBSTANCE: alternating-current spark protection unit comprises transformer with magnetic shunt, two bilateral triode switches, two voltage-limiting circuits consisting of in-series suppressor and resistor, which common point is coupled to control electrode of the respective bilateral triode switch; each circuit is connected by its one end to the ground while the other ends and power leads of the triode switches are coupled to the respective outputs of the transformer secondary windings. The common point of suppressor and resistor may be connected to control electrode of the triode switch thorough an element with non-linear volt-ampere characteristic. Primary winding of the transformer may be coupled to source of spark voltage through a fuse. Primary and secondary windings of the transformer may be placed at lateral rods of E-core, which medium rod has a non-magnet gap. Two voltage-limiting circuits with triode switches may be doubled or tripled depending on the required level of intrinsic safety.

EFFECT: increasing spark-proof power.

5 cl, 3 dwg