| 摘要 |
Circuit for protection of three-phase induction engines against dissymmetrical operation and overloads comprising an overvoltage unit whose output is connected via a resistor with the base of a transistor, whose collector is connected to the coil of a relay, a delay circuit, a threshold circuit, a reference voltage circuit, a power supply, three current-to-voltage converters whose positive output terminals are connected to the inputs of a full-wave three-phase rectifier, whose positive terminal is connected via the first input and the first output of the delay circuit with shorted negative output terminals of the current-to-voltage converters, which are at the same time connected via a diode to the output of the voltage reference circuit, characterized in that the negative terminal of the full-wave three-phase rectifier (PR1) is connected with the moving contact of a potentiometer (PO), between the positive output terminals of the current-to-voltage converters (IU1, IU2, IU3) and the second input (we2) of the delay circuit (UZ) a half-wave three-phase rectifier (PR2) is connected, the second output (wy2) of the delay circuit (UZ) is connected to the input (we) of the threshold circuit (UP), between the input (we) of the threshold circuit (UP) and the output of the overvoltage unit (CP) the first diode (D2) has been connected, and its anode is turned towards the input (we) of the threshold circuit (UP), between the output (wy) of the threshold circuit (UP) and the base of the transistor (T) whose collector is connected to the coil of the relay (P), the second diode (D3) has been connected, and its cathode is turned towards the output (wy) of the threshold circuit (UP), [à]<IMAGE>
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