Expert system measures harmonics and EMC

The effects of power system harmonics are becoming more and more important as the number of rectifier controlled motors, discharge lamps, and television equipment grows in industrial and utility power systems.The author describes how a modular expert system for measurement and analysis of power system harmonics and electromagnetic compatibility was developed. The system is capable of sampling up to eight channels (either voltage or current) with a sampling frequency of 30 kHz. The measured and digitized values are stored on a hard disk. Discrete Fourier transformation (DFT) analysis may be carried out online for preliminary evaluation and display of the harmonics. This modular, PC-based system may be applied to a variety of industrial and utility electric system analysis tasks, and also used in education.<>