Sampling circuit for open-phase and earth leakage protection

• Main Authors: LAN XIULIN, LI YANLING
• Format: Patent
• Language: Chinese; English
• Published: 05.11.2008
• Subjects: CONVERSION OR DISTRIBUTION OF ELECTRIC POWER; ELECTRICITY; EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS; GENERATION; MEASURING; MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES; PHYSICS; TESTING

The utility model provides a sampling circuit with phase-failure and current-leakage protection, which can solve the technical problems of complicated structure, expensive price and difficult repair of a phase-failure and current-leakage protection device of an underground explosion-proof motor. The sampling circuit comprises a phase-failure detection sampling circuit and a current-leakage protection sampling circuit, which is characterized in that the phase-failure detection sampling circuit consists of a rectifier-filter circuit (D), a comparison circuit (E) and a photoelectric isolation circuit (F), three-phase AC current outputs a level signal after the rectification and the filtration, outputs a switch signal after the comparison by the comparison circuit and transmits the signals to a programmable controller by the photoelectric isolation circuit (F); the current-leakage protection sampling circuit compares the detection voltage of a high-voltage contactor and the reference voltage by a comparator and t