Contactless Thermal Online-Monitoring of Electrical Equipment Under Load at High Voltage to Determine the Load Level and Damage Avoidance

摘要

The meanwhile high age of the electric energy distribution in the industrialized countries as well as the avoidance of new investments, the target to reduce maintenance resources and to use the assets at the maximum efficiency, accelerate the desire for the implementation of online monitoring systems. One of the most important physical dimensions for the judgement of the condition of an electrical device is the temperature at the current path. Problematical, with the temperature monitoring is that the measuring places are often not directly accessible or on high voltage level, so that measurements need to be done contactless. Today new electronic components with miniaturized dimensions and low energy consumption allow very small design applications, so that the implementation inside high voltage equipment will be possible using of energy harvesting. The measurement of the temperature inside or at electrical equipment like switchgear, HRC fuses, GIS- or GIL-systems, cabinets, cable connections, cable joints or bushings allows the judgement of the load level and the estimation of the thermal stress of the insulation or contacts. Additional functionality will be generated when the ongoing current is measured together with the temperature. The analysis of both parameters, allows the estimation of e.g. contact's condition as well as the thermal condition of high voltage HRC fuses before these will explode due to aging cased by overheating. The detection of thermal stress due to short circuit current flow is possible too.