AN ELECTRIC FIRE WATCHING SYSTEM TO USE A CARRIER WAVE OF POWER LINE AND PHASE DETECTION OF EXCESSIVE ELECTRIC CURRENT

摘要

An electric fire watching system using a carrier wave of a power line and phase detection of a transient current is provided to prevent fire progress by opening an electromagnetic switch and supplying power to an emergent lamp. A first sensor detects a leakage signal and generates a signal according to a current difference between currents flowing through electric lines. A second sensor detects phases of an excessive current and an instantaneous peak current and sends the detected result to a main calculation board. An electromagnetic switch blows circuit by the control of main calculation board when the short circuit is detected. The main calculation board controls an audio board and a telephone modem. An intermediate frequency generator predicts the short circuit and generates an intermediate frequency of 5KHz. An impedance load includes parallel-connected resistor, reactor, and condenser. The telephone modem contacts a user by the number of display. The audio board broadcasts a voice signal stored in a memory chip. An error time memory stores the time when the excess current occurs. A wideband receiver receives and amplifies a signal between 10 KHz and 3 MHz and supplies an interrupt signal of a high speed microchip in the main calculation board. A receiving board supplies in real time a spark wavelength detected at the wideband receiver.