{"references": ["Jiahong He,Ravi S. Gorur \"Charge Simulation Based Electric Field Analysis of Composite Insulators for HVDC Lines,\" IEEE Transactions on Dielectrics and Electrical Insulation.,vol. 21, no. 6, pp.2541-2548, Dec. 2014.", "Jing Li, Zongren Peng, Yong Feng, Xiaoyong Fu, Tianxi Xie \"Electric Field Calculation and Grading Ring Optimization of Composite Insulator for 500kV AC Transmission Lines,\" International Conference on Solid Dielectrics, Potsdam, Germany., pp.1-4, July. 2010.", "B. Marungsri, W. Onchantuek, A. Oonsivilai, T. Kulworawanichpong \"Analysis of Electric Field and Potential Distribution along Surface of Silicone Rubber Insulators under various contamination conditions using Finite Element Method,\" International Journal of Electrical and Computer Engineering, pp.156-166, March. 2010.", "Rahul Krishnan, Subhajit Samanta, Sudha R&K Govardhan \"Electric Field Analysis of High Voltage Insulators,\" International Journal of Computer Science and Informatics., ISSN:2231-5292, vol. 1, Iss.4, pp.31-35, 2012.", "IEC Standard-61009 \"Insulators for Overhead Lines Composite Suspension and Tension Insulators for A.C. Overhead Lines with a Nominal Voltage Greater Than 1 000 V Definitions, Test Methods and Acceptance Criteria\", 2008.", "Field Guide: \"Corona rings for polymer insulators-selection, inspection and assessment 1008741\", EPRI. Pala Alto, CA, Mar.2005.", "Field Guide: \"visual inspection of NCI: Ricision 1\", EPRI. Pala Alto, CA 1008739, May.2004.", "Field Guide: \"Corona and Arcing Inspection of transmission lines\", EPRI. Pala Alto, CA 1001910, Oct.2001.", "IEC Standard-60437 \"Radio Interference test on High Voltage Insulators\", 2005.\n[10]\tIEC Standard-60060-1 \"High voltage Test Techniques Part-1 General Definitions and Test Requirements\", 2010.\n[11]\tIEC Standard-60060-2 \"High voltage Test Techniques Part-2 Measuring Systems\", 2010.\n[12]\tIS Standard-731 \"Specification for Porcelain Insulators for Overhead Power Lines With A Nominal Voltage Greater Than 1 000 V\", 2001."]}

In electrical power system, high voltage insulators are necessary for consistent performance. All insulators are exposed to different mechanical and electrical stresses. Mechanical stresses occur due to various loads such as wind load, hardware and conductors weight. Electrical stresses are due to over voltages and operating voltages. The performance analysis of polymer insulators is an essential, as most of the electrical utility companies are employing polymer insulators for new and updated transmission lines. In this paper, electric field is analyzed for 400 kV silicone (SiR) composite insulator by COULOMB 3D software based on boundary element method. The field results are compared with EPRI reference values. Our results proved that values at critical regions are very less compared to EPRI reference values. And also experimentally 400 kV single V suspension string is evaluated as per IEC standards.