B. Banhthasit, K. Tonmitra, A. Suksri, A. Kaewrawang, and M. Leeparkobboon, “A comparison on leakage current of 22 kV porcelain insulator by using rotating wheel tester with high voltage AC and impulse voltage excitation”, Eng Appl Sci Res, vol. 38, no. 3, pp. 297–304, Apr. 2013.