Contaminated Insulator-line Monitoring System Design

Near industrial, agricultural, or coastal areas, contamination is a frequent cause of insulator flashover, most cases of which result in lengthy service interruptions. Utilities spends significant amounts of money on insulator washing and cleaning before the restoration of the service. Laboratory studies and industrial experience have shown that both contamination and wetting of insulator surfaces, which initiate the flow of leakage current, are required for insulator flashover. The leakage current leading to flashover has distinctive stages of development. Flashover is preceded by dry-band arcing and extension of the arc to bridge the insulator. This combination significantly modifies both the magnitude and shape of the leakage current.Insulators leakage current has a close relationship with insulators contamination and humidity state, so it can provide an integrated reflection of the course of contamination flashover. The contamination flashover on-line monitoring device introduced in this paper predominates the insulators insulation degree by measuring leakage current, environment temperature and humidity. With the help of the device, an active partial aperiodic cleaning method will substitute the former passive general fixed cleaning method in order to prevent the contamination flashover to a larger extent.The power of this monitoring device is made up of novel switch voltage regulation circuit and linear voltage regulation circuit, the electricity of which is directly supplied by high voltage line. Being added an anti-phase compensating winding, this device, which is placed between high voltage line and first insulator, makes the synthesized magnetic field in magnetic core reach a dynamic balance, and thus solves the problems from remanence and assures the measurement accuracy. In this device MSP430 was selected as CPU to complete the task of sampling, processing and saving data. The backstage computer in the monitoring room communicates with each field device by wireless system. The computer receives and processes the data from field on time in order to predict alarm or give an alarm on the insulators contamination and humidity state. It was proved that this device can predict the occurrence of contamination flashover successfully.