Substantiation of On-Line Monitoring Methods for Surge Arrestors of Closed 110 kV Switchgear

High voltage nonlinear surge arrestors (HVSA) are electrical devices designed to protect the equipment of power supply systems from switching and lightning overvoltages. The article considers the HVSA installed in closed 110 kV switchgears of the furnace-ladle units at the metallurgical plants. It is highlighted that the impact of external factors may cause loss of the arrestor's sealing thus making it not suitable for use. In this connection, the development of methods and systems for monitoring the HSV A technical state is relevant. The analysis of known methods for frequent control is provided with their advantages and disadvantages described. The significance of HVSA thermal imaging control is emphasized. The results of frequent measurements are further provided. It is shown that due to the complexity of the device design, thermal imaging control cannot provide a reliable measurement of the temperature at the surfaces of voltage-variable resistors. The requirements towards the HVSA on-line monitoring system are stated. According to them, one shall conduct a continuous monitoring of the thermal state of each HVSA section and also the monitoring of the root-mean-square values of the harmonic components of the conductive currents in each phase.