Wind Tunnel Studies of the Insulator Contamination Process

This paper describes a small wind tunnel that was constructed to study the effects of wind, electric field, and insulator geometry on the insulator contamination process. The wind tunnel is operated with a kaolin clay and NaCl salt injection system. A voltage source is also available. Several insulator shapes, with voltage applied, were exposed in the wind tunnel. Preliminary test results indicate that wind tunnel contamination deposition is similar to that observed on naturally contaminated insulators. Sampling methods currently in use may not allow realistic comparison of flashover performance between uniform and nonuniform contamination. Other preliminary observations indicate that the effect of the electric field on contamination rate is greater than previously estimated. Estimation of site severity for insulator design, when using unenergized insulators, should be corrected for this effect.