Tests and Developments in Connection With Hot-Line Insulator Washing

The tests definitely have shown and subsequent field experience have demonstrated that the high pressure water stream method of cleaning insulators is both practical and more economical than other methods used. It presents one of the best opportunities for the reduction of the maintenance cost on transmission and distribution lines. A high pressure compact and solid water stream will remove practically 100 per cent of ordinary dust and dirt and from 50 to 85 per cent of bad contamination. tion. The flashover voltage is raised to practically 100 per cent of a new clean insulator when ordinary dust and dirt are removed. The flashover voltage is increased enough so that the badly contaminated insulators may remain in service if washed frequently. Tests have shown very definitely that the stream of water should hit the insulator before it breaks into a spray if a good cleaning job is obtained, especially if the insulator is contaminated badly. Cleaning insulators with a high pressure stream of water is a safer method than wiping by hand. If the workman maintains the generally recognized safe working distance, he will not receive a shock or a dangerous leakage current through the stream of water. It eliminates the ever present hazard of a lineman climbing a pole supporting an energized line and an unenergized line and inadvertently wiping the energized insulators. The reduced expense of cleaning insulators will allow more frequent cleaning and will eliminate to a very great extent pole top fires.