Novel capacitive proximity sensors for assessing the aging of composite insulators

- A novel electrode structure consisting of a variable spacing interdigital electrode (VS-IDE) was proposed.
- The VS-IDE structure sensor was optimized to confine the electric field line within the sheds under test.
- The optimal sensor exhibited high amplitude, high sensitivity, and excellent stability.
- The capacitive proximity sensors can be used for quantitative evaluation of the aging of silicone rubber sheds.

A novel electrode structure consisting of a variable spacing interdigital electrode (VS-IDE) was proposed for assessing of the aging of silicone rubber sheds with variable thickness. A series of numerical simulations and experiments have been carried out to investigate the influences of finger number, unit width, and metallization ratio on the signal strength and penetration depth of sensors with a traditional interdigital electrode structure. According to the relationship between the penetration depth and the unit width, the width of each finger that composed the VS-IDE structure sensor was optimized individually to confine the electric field line within the sheds under test. Experimental results showed that compared to the other sensors, the optimal sensor exhibited high amplitude, high sensitivity, and excellent stability against the effects of environmental humidity. The developed capacitive proximity sensors have been used for assessing of the aging of silicone rubber sheds in composite insulators, and the feasibility of assessing insulation degradation by quantitative capacitive techniques is demonstrated.