Measurement of transient electric fields and analysis based on wavelet

Electromagnetic interference is a major concern in modern power systems as increasing control is being performed by highly susceptible electronic circuitry. It is therefore necessary to characterize this interference. This paper introduces a measurement system based on spherical sensor and optical insulation system, and using this system to measure the transient fields of impulse in laboratory. The wavelet transform is well suited to wide-band signals, such as the typical electromagnetic transient in power system. And the ability of wavelet to focus on short time intervals for high frequency components and long intervals for low frequency components improves the analysis of signals with impulses and oscillations. The basic principles of wavelet analysis are set forth, and examples using the property of multiresolution to de-noise and reconstruct the signal