DEVICE FOR PROTECTION AGAINST ELECTRO-STRIKING ACTION OF BACK ELECTROMOTIVE FORCE OF MINE ASYNCHRONOUS MOTOR Russian patent published in 2025 - IPC H02H7/08 

FIELD: electrical engineering.

SUBSTANCE: device for protection against electric striking action of reverse electromotive force of mine asynchronous motor relates to the field of electrical engineering. Device contains two capacitors, resistor, two bridge rectifiers, galvanic isolation unit, thyristor, as well as a voltage transformer, the primary winding of which is connected to the phase conductors at the input of the three-pole group of power contacts of the contactor, equipped with low-current open and close contacts mechanically connected to the three-pole group of its power contacts, and the secondary winding of the voltage transformer is connected to the input of the first bridge rectifier, between the terminals of the positive and negative poles of which the first capacitor is connected. Output of the positive pole of the first bridge rectifier is connected through the low-current open contact of the contactor to the first output of the second capacitor, the second output of which is connected to the first output of the resistor. Input circuits of the second bridge rectifier are connected to the phase conductors at the output of the three-pole group of power contacts of the contactor, and to outputs of positive and negative poles of this rectifier, respectively, thyristor is connected by anode and cathode, to control electrode and cathode of which the output of galvanic isolation unit is connected. Second output of the second capacitor and the first output of the resistor are connected to the first output of the input circuit of the galvanic isolation unit, the second output of which is connected to the output of the negative pole of the first bridge rectifier. Second output of the resistor and the first output of the second capacitor are connected to the first and second outputs of the low-current closed contact of the contactor, respectively.

EFFECT: providing the possibility of suppressing electro-striking action in the circuit of power connection of the starter by means of post-switching short-circuiting of phases at the output of its contactor while simplifying the circuit implementation of the device, improving reliability and simplifying its adaptation to the circuit and design of the starter.

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