The Study On Anti-Fire Residual Current Alarm Device And Its Technology

Residual current operated protection is mainly studied in this paper, based on the thorough analysis of fire caused by electric fault, the technological measures against fire have been determined. According to relative national standards for anti-fire RCDS, the application of anti-fire residual current delay in low voltage distribution system is researched. If leakage current exists in power lines under normal condition, there will be a phase angle difference between the normal leakage current and the fault current when an electric shock hazard occurs. The residual current will decrease consequently, thus a dead zone of protection exists. In this paper, a new leakage current operated protective model is established. The detected residual current can be restituted into A phase,B phase and C phase respectively, then the abrupt residual current values of A phase,B phase and C phases can be figured out, residual currents'variation is taken into consideration as a criterion to represent the fault current, finally residual operated dead zone is eliminated. The device has the ability of automatic tracking, in other word the residual current operated value is changed according to the frequency of power nets, so the reliability of residual current operated devices is improved. In order to prevent fires caused by electric, the temperature of wire is sampled and analyzed. PIC microcontroller of Microchip is used as controller, its hardware is designed. Its software is completed by assemble language. Then the detecting, real-time discharging and displaying are realized and reasons and residual current value are memorized. At last, anti-fire residual current alarm device is completed.