Abstract
The dielectric properties of the electrical insulation materials is of great importance to the safe operation of the power system. As a promising technique in the field of material testing and with the very adaptive physical modeling of wave transmission process, terahertz wave was used to measure the dielectric properties of five commonly used insulation materials by two methods in this paper. When excluding the echo pulse from the reference signal and the sample signal, a better signal-noise ratio and a wider effective frequency band of spectrums can be obtained. Alternatively, the dielectric properties can also be achieved by separating the main pulse and echo pulse from the sample signal. The latter method makes the sampling of reference signal unnecessary. Furthermore, the dielectric properties of materials were also measured on a relative lower frequency band (1Hz–1MHz) by the broadband dielectric spectrometer. Compared with a relatively lower frequency band, due to the polarization, the dielectric constant of the tested insulation materials was lower on the terahertz band while the dielectric loss tangent was generally higher except the epoxy resin.
Highlights
The electrical insulation materials play an important role in the insulation coordination of overhead power lines [1]
In this paper, two methods using the terahertz wave technique were proposed to investigate the dielectric properties of five electric insulation materials which were commonly used in the power system
The system echo pulse and the reflected echo pulse were excluded in both the reference signal and the sample signal
Summary
The electrical insulation materials play an important role in the insulation coordination of overhead power lines [1]. The broadband dielectric spectroscopy (BDS) is a common method and a powerful tool to explore dielectric properties of materials on timescales across several orders of magnitude [2] It is based on the interaction of an external field with the electric dipole moment of the sample, often expressed by permittivity, and registers the relationship between the current and voltage (magnitude and phase) for a set of electrodes containing the material under investigation. This paper measured the dielectric constant ( called relative permittivity) and dielectric loss tangent of five electrical insulation materials by both the BDS and the terahertz wave method These five insulation materials, including epoxy resin, epoxy glass fiber, polyethylene (XLPE), electrical porcelain, and high temperature vulcanized (HTV) silicone rubber, are widely adopted in the power system. The test results obtained by terahertz wave method and BDS were compared and analyzed in the perspective of dielectric physics theory
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