Condition assessment of porcelain and toughened glass insulators from residual strength tests
Transmission and distribution networks of most utilities worldwide have a substantial quantity of porcelain and toughened glass insulators that have been in service for over 30 years; a number that has been traditionally considered as useful life for planning purposes. Many utilities are implementing programs to replace older or defective insulators for improving reliability and also for upgrading their lines. In order to help prioritize line maintenance it is important to identify the condition of insulators and replace those insulators whose performance has reduced significantly from their new condition, hence threatening reliability. In this project, porcelain and toughened glass insulators that were in service for periods ranging from 10-30 years were removed from several locations. Electrical (puncture strength, flashover voltage) and mechanical (tensile strength) tests were performed to assess any reduction in performance. Diagnostic tests such as analysis of bonding agents, identification of internal failure paths were performed to understand failure causes. A sufficiently large number of samples were evaluated and this permitted condition assessment with statistically significant confidence limits
A neural network based method for the diagnosis of ageing insulators
This work attempts to apply an artificial neural network in order to diagnose ageing transmission line insulators. The insulator leakage current harmonic components are used as the input variables of the artificial neural network. The data used to train the network and test its performance is derived from experimental measurements carried out in artificial climatic chamber. The experimental result and neural network simulation results are presented accordingly. This novel method of ANN application can be viable in online diagnosis of insulators in service and lifespan estimation yielding efficient and effective predictive maintenance practices for power utilities in a cheap and less time-consuming manner.
Calculation of Maximum Harmonic Currents and Voltages on Transmission Lines
This paper presents a method for calculating the location and magnitude of the maximum harmonic currents and voltages on a transmission line, given calculated or measured terminal values. This information is normally unavailable. However, as the number of harmonic sources on the system increases, the location and magnitude of these harmonic maximums will be of increasing importance.