| 摘要 |
The electronic device for protecting alternating current electromotors against current overload and asymmetric power supply, whose voltage, supplied by a current transducer (8), proportional to the intensity of the current through the electromotor, is rectified by a precision rectifier (9) and applied, through a filter, to a window comparator with operational amplifiers (16, 17), whose threshold voltages are obtained with diodes (18, 19, 20). The window comparator engages relay (28) via a logical circuit, when the value of the current through the circuit of the electromotor does not fall within the normal operational range. The adjustment of the device for a certain type of electromotor is achieved by operating a potentiometer (12), until a light-emitting diode (15) is turned on. The diode (15) is controlled by the comparator (13), whose reference voltage is obtained through the polarisation of a Zener diode (14).
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