The Experimental Studies Of Infrared Thermal Imaging To Prevent Electrical Wiring Fire

Along with the development and widely using of electrical equipment, there are many problems in operation of electrical equipment and electrical wiring. Those problems focus on electrical accidents and fire hazards. In operation of electrical wiring, hazards as short-circuit, overload, poor contact, resistance of line or cable’s connection overlarge, which cause line overheat and fire accident, causing personal injuries and property damages. So it’s important to study the temperature field and infrared testing technology for the judgment of electrical wiring’s working operation, according to character of electrical wiring. And it’s valuable for the reliability of electrical wiring.First, through the researches and analyses of the thermal radiation theory, infrared thermal equipment, measurement error of infrared thermograph, and influent factors of measurement error, the correction formula of measurement error was derived. Based on the temperature field, the structure of wire, and the principle of heat transfer, an analytical model for wire core temperature is established. Depending on the model, the wire core temperature of different wires can calculated with different conditions of ambient temperature and current. The influent factors of analytical model includes structure parameters of wire, current, ambient temperature, heat transfer coefficient.Under the condition of ambient temperature and current, through24designed experiments, based on BV2.5PVC insulated conductor with copper wire, measurement of wire temperature can be accomplished using an infrared thermal imager. Measurement error is0.11～1.28percent by analyzing the experimental data. With a constant current, the surface temperature and core temperature rises with increasing ambient temperature; under constant ambient temperature, the surface temperature and core temperature rises with increasing current, and the upward trend of surface temperature and core temperature rises as the same. The upward trend of wire temperature is smaller, when current is small. The upward trend of wire temperature is larger with large current.The data of experiment are fitted linear regression line. The calculation model of wire core temperature is gained as To=Tw+0.1863(Tw.-Tp)-0.092. The error can vary by no more than about1percent. The simplified calculation model of wire core temperature is gained as To简=Tw+0.2(Tw-Tf). The error can vary by no more than about1.5percent. The wire core temperature can be calculated by surface temperature and ambient temperature in the detection procedure. Gaining a correct wire core temperature is important to prevent electrical fire accidents.