Modeling of Electromagnetic Environment Inside a Factory Building via Finite Difference Time Domain Method

Increased use of factory automation (FA) apparatus raises concern over electromagnetic interference among electronic devices at the industrial sites. The purpose of the present paper is to discuss modeling of electromagnetic environment inside a factory building via Finite Difference Time Domain (FDTD) method. The principal noise frequency radiated by an inverter-motor system in the building is between 1MHz and 10MHz. Three-dimensional simulation code is verified against measurement of magnetic field distribution inside a simulated building and a laboratory. Effect of wire reinforced concrete wall on the numerical modeling is discussed. As long as the noise source is far away from the wall, the reinforced concrete wall can be modeled as a simple metallic wall reflecting the electromagnetic wave of the frequencies between 1MHz and 10 MHz. When the noise source is embedded inside the wall, however, each reinforcing wire must be modeled.