Influences of Relative Humidity on the Electric Field and Potential on Suspension Insulator String

This paper described to study the influences of relative humidity on the electric potential and electric field around the suspension insulators string which used in the 115 kV transmission system associated with ANSI standard. The suspension insulators string was used by Provincial Electricity Authority (PEA) in Thailand. Thailand is located in the tropics near the equator. It is hot and humid all year covered unless the area is in the central region and up. Relative humidity is lower in winter and summer. The summer Relative humidity is the lowest ebb in years. In such an average relative humidity is 72-74 percent, and down to 62-69 percent in the summer. The Finite Element Analysis (FEA) program was used to simulate the electric potential and electric fields. This simulation was compared the characteristic of suspension insulator due to different humidity between 75-80%RH. The Relative Humidity was based on mean of 5-year, average from 2010-2014 relative humidity by region since 2010-2014. The combination of humidity of the fog, rain, or dew and pollutant conductivity may cause insulator flashover. So, moisture thus influencing the behavior of the dielectric insulators has been investigated to reduce the impact of the system. This paper reports the simulation results on the investigation on the effects of humidity on potential and electric field of suspension insulator.