Abstract: An autonomous inverter includes a three-phase thyristor bridge (7), a diode bridge (14), commutating capacitors (15), and communicating thyristors (16 and 17). AC leads of the thyristor bridge (7) are connected, via the commutating capacitors (15), to respective leads of the diode bridge (14). DC leads of the diode bridge (14) are connected to the like leads of the thyristor bridge (7) via the commutating thyristors (16 and 17). A master oscillator (24) of the autonomous inverter has the output thereof connected to a first input of a distributing unit (23). The autonomous inverter is also provided with two voltage dividers (18), the first arms of each divider (18) comprising three star-connected resistors (19), while the second arms thereof comprise resistors (20) inserted between the neutral points of the stars and the ground. Outputs of the voltage dividers (18) are connected to inverting and non-inverting inputs of a differential amplifier (21).

Abstract: A device for failure detection in series-connected semiconductor rectifiers (1) comprises transformers (2) whose number is equal to that of the rectifiers (1) and which comprise input windings (3), supply windings (6), and additional parallel-connected windings (9), RC-circuits whose number is equal to that of the rectifiers (1), having resistors (4) and capacitors (5), and also a pulse generator (7), and a measuring element (8).The input winding (3) of each transformer (2) has one lead-out thereof connected to a cathode of the respective rectifier (1), and another lead-out to the capacitor (5) of the respective RC-circuit. The resistors (4) of each RC-circuit are connected to the anodes of each rectifier (1). The supply windings (6) of the transformers (2) are connected to one another in series and connected by one terminal to the first lead-out of the pulse generator (7).