Study On Saturation Contamination Characteristics Of Composite Insulators Considering The Influence Of Charging And Environmental Factors

Composite insulators have been widely used in the field of transmission lines external insulation because of their advantages like light weight and good hydrophobicity.Under the effect of environmental factors,the surfaces of composite insulators in operation will be stained by contamination cont inuously until reaching dynamic saturation.If the contamination on the surface cannot be cleaned in time,partial discharge and even pollution flashover accidents may be caused,which will lead to serious economic losses.However,excessive cleaning will also increase the labor intensity on site and reduce the reliability of power supply.Therefore,studying the contamination saturation characteristics of composite insulators under the influence of charging and environmental factors is of significance to scientifically plan the insulator cleaning cycle and improve the cleaning efficiency.In this paper,combined with the stress of pollution particles in the process of composite insulator surface contamination,an insulator saturation fouling test platform is designed.Based on the field charging theory,the platform is able to control the charges of contaminated particles,which accelerates the saturated fouling process and realizes the quantitative control of environmental factors in the test process at the same time.By utilizing the platform to launch the saturation tests of composite insulator pieces,the paper obtains saturation contamination characteristic curves under different charge mass ratios,contamination particle sizes,electric field intensities,voltage types,wind speeds and relative humidity.According to the test results,except for wind speed and relative humidity,the other factors only affect the contamination accumulation speed instead of the final saturated contamination quality of the composite insulator pieces.Increasing particle charge-mass-ratio or electric field intensity will lead to the increase of composite insulators’contamination accumulation speed.At the same voltage level,the contamination accumulation speed under DC voltage is higher than that under AC voltage.The influence of small size particles on accumulation is more significant when the charge-mass-ratio is low.The influence of increasing wind speed on the contamination accumulation speed and saturated contamination quality is related to the particle size,as a result of which the large size particles will encounter difficulties to adhere to the the surface of composite insulators at relatively high wind speeds.The contamination accumulation speed and saturated contamination quality will swell with the increasing relative humidity.In order to further verify the above contamination accumulation law,the wind tunnel test system is utilized to study the contamination growth characteristics of FXBW-35/70-2 composite insulators’surfaces with the accumulation time under various wind speeds,voltage levels,contamination types and contamination concentrations.In addition to verifying the influence of wind speed,the test data indicate that contamination types have certain influence on the fouling process of composite insulators.The diatomite is easier to deposit on the surface of composite insulators than SiO₂ powder.The increase of the voltage level or pollution concentration does not affect the saturated concentration quality while accelerating the concentration accumulation process.