A Practical Application of Substation Insulator Maintenance at a Steel Mill Factory in South of Iran

摘要

In addition to natural pollution resources, industrial pollution resources such as steel mill and cement factories are the other dilemmas for power stations, which especially located at the vicinity of them. Near industrial areas, contamination is a frequent cause of insulator flashover, most cases of which result in lengthy service interruptions. Utilities spend significant amounts of money on insulator washing and cleaning before the restoration of the service. Accumulated contaminants on insulation surfaces combined with moisture provide conductive paths that result in flashovers and undesirable outages. A 230 kV substation located at a steel mill factory in south of Iran with semi-desert climatic condition is considered as a case study. In this substation the industrial contamination condition is severe and periodic insulator hand cleaning is performed in substations, which involve de-energized manual wiping. This is obviously an approach that was time consuming and costly and also due to solidity of hard pollution layer not so effective. Wind drives magnetite airborne contaminant particles onto the insulator surfaces. The continuous deposition of these particles increases the thickness of these deposits. After a long time (months, years) the deposits are stabilized and a thin layer of solid deposit will cover the insulator. Surface contamination make pollution induced flashovers a much broader problem. In order to investigate the influence of magnetite pollution on insulator contamination performance in such a this heavy industrial contamination areas, and to review the present design and maintenance criteria of insulators there, NRI carried out a series of ESDD (Equivalent Salt Deposit Density), DDG (Directional Deposit Dust Gage) and Layer conductivity measurements and leakage current monitoring. Exposure tests were conducted at a site located in an industrial complex area. According to the significance of continuous power delivery for the production lines and the extensive losses due to previous outages, efficient insulation maintenance seems to be necessary. Therefore, several test stations are sat up at the factory site and periodical hand cleaning, insulator replacement, RTV silicon coatings are assessed as insulation maintenance approaches. In this regard in the first step porcelain station post insulators units where flashover has been experienced on bus bar support, were replaced with composite ones. After 3 years site exposure and without applying any cleaning program No fault has been reported. For apparatus type insulators as a case study the evaluation performance of RTV silicon coating on a 230 kV transformer feeder as a maintenance strategy was considered. The main problem with R.T.V silicon coating in this substation due to hardness of pollutant deposit is primary surface treatment of polluted insulators before application of coating. In this paper, efficient maintenance approaches to overcome the power outages are presented. The Assessments based on the field studies show significant increase of the power network reliability.