An acoustic emission method for on-line monitoring the contamination-causing flashover of insulator
This paper presents an acoustic emission (AE) monitoring method. When a partial discharge occurs, there is an instantaneous release of energy, some of which is emitted as acoustic energy. The pollution severities of insulators in-service can be monitored and accordingly threaten to the insulation of power grid is evaluated by detecting the sound signals. To prove this AE monitoring method, artificial contaminations experiments are carried out. The essential information about the relationship of AE signal and PD are obtained in different moments of the whole process of flashover. The studied method is a new way of AE technique in monitoring and characterizing defects of electrical power equipments in-service.
Estimation of high voltage insulator contamination using a combined image processing and artificial neural networks
In this paper, contamination level estimation tool for high voltage insulators has been developed. A digital camera has been used to capture pictures. Image processing has been used to extract needed features form the captured images. Two types of features were considered. The first is “histogram based statistical feature” while the second is “singular value decomposition theorem based linear algebraic feature”. Using extracted features, a neural network has been successfully designed to correlate the insulator captured image and the contamination level. Testing of the developed estimation tool showed a very high successful rate in estimating the contamination level of unseen insulators. It is expected that a successful deployment of the developed tool will eliminate the need of human intervention in determining the time and location of insulators to be washed.
Effect of temperature on optical fiber transmission.
Results are presented concerning the effects of temperature on the transmission properties of various optical fibers including a silicone plastic clad, an acrylic plastic clad, and CVD step-index fibers both with and without polyurethane jackets. Results are presented for the normalized transmitted power vs temperature, the index of refraction vs temperature, and induced attenuation coefficients vs temperature. The data show that the intrinsic transmission of a CVD fiber is independent of temperature over the -110 to +150 C range. Plastic clad fused silica fibers are subject to transmission losses at lower temperatures due to changes in the optical index of the cladding polymer. Acrylic-clad and plastic-clad silica fibers also show transmission losses at lower temperatures, but to lesser extents.