DEVICE FOR DETECTING SHORT-TERM BREAKDOWN OF PHASE OF ELECTRIC POWER FREQUENCY TRANSFORMER WHILE PRESERVING OPERABILITY AND CONTROLLING OF DRIVE AT TIME OF BREAK Russian patent published in 2017 - IPC H02H3/24 

FIELD: electricity.

SUBSTANCE: to detect phase failure in the current collector on the resistors, a dummy zero of the circuit with a neutral point is realized. The voltages of each phase with respect to the neutral point through the zener diodes and current-limiting resistors are rectified by diode bridges and connected to opto-transistors whose outputs are phase state signals (logical zero in the absence of an opening and a logical unit in the presence of an opening) are connected to the inputs of the microprocessor of a drive control system. The support small power transformer, connected to phase C, after rectifying and filtering its secondary voltage, provides power to the microprocessor when the drive is turned on. The microprocessor, according to phase signals at its inputs, controls the connection to the phases of the current take-off of the primary side of the main power supply transformer of the microprocessor and the control circuits. In the absence of breaks, the microprocessor with the corresponding opto-resistors connects phase A to the beginning, and phase B to the end of the primary side of the main transformer. If the phase A is broken, the microprocessor with the corresponding optosymmistors starts the winding from phase A and switches it to phase C after 10 ms, and in the event of termination, disconnects the beginning of the winding from phase C, and after 10 ms connects it to phase A. If the phase B of the microprocessor is cut by the corresponding opto-resistors the end of the winding disconnects from phase B and after 10 ms connects to phase C, and when the breakage is terminated, it disconnects the end of the winding from phase C and after 10 ms connects it to phase B. The phase C interruption does not cause the transformer winding to be switched. If there is two phases break, the drive switches off.

EFFECT: maintenance of the operation and controllability of the crane electric drive during short-term phase breaks on the trolley current collector of a frequency-controlled electric drive, thereby avoiding sudden surges and dynamic overloads in the supporting structure of the crane.

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