Epoxy Resin Insulators: Technical Practices For Preventing Flashover From Pollution In Instrument Transformers

In the actual operation of power systems, the outdoor environmental challenges faced by transmission and transformation equipment are far more complex than imagined. For critical metering and protection equipment such as instrument transformers, the external insulation performance directly determines their operational stability. The role of high voltage epoxy in the structure of current transformers is no longer just electrical isolation, but also requires the ability to resist the erosion of harsh environments, especially in the core task of preventing flashover.

Interface Optimization of External Insulation Structure

When operating outdoors, the surface of the instrument transformer's skirt easily accumulates industrial dirt or natural dust. Traditional single-material insulation tends to form a continuous water film on the surface under long-term humid conditions, leading to a surge in leakage current. A common solution is to use a double-layer composite structure: the inner layer is cast from epoxy resin to ensure overall mechanical strength and electrical insulation; the outer layer is composite with silicone rubber. This design utilizes the excellent hydrophobicity and hydrophobic migration properties of silicone rubber; even if the surface is covered with dirt, water vapor will only condense into isolated water droplets, preventing the formation of a conductive path. In this type of composite structure, the epoxy resin insulator not only serves as a supporting framework but also forms a seamless interface with the external anti-pollution layer through "homogeneous bonding" technology or physical interlocking, eliminating the risk of interlayer discharge.

Deep Protection of Anti-pollution Performance

Driven by the demand for anti-pollution, the surface treatment process of the external insulation of instrument transformers is constantly being refined.

• Anti-aging and Self-cleaning: Considering the potential chalking of epoxy materials under long-term outdoor UV exposure, some designs apply fluorocarbon paint to the epoxy resin layer. The fluorocarbon paint coating has extremely low surface energy, excellent hydrophobicity and self-cleaning properties; rainwater can wash away dust, effectively delaying the aging process of the insulation layer and extending anti-pollution capability throughout the product's entire life cycle.

• Electric Field Uniformity: Pollution flashover often begins with partial discharge. By setting a shielding mesh structure in the inner insulation layer and using an epoxy resin vacuum casting process, the electric field distribution inside the instrument transformer can be effectively uniformized, eliminating areas with excessively high local field strength and reducing the probability of surface discharge caused by pollution at its source.

Through material composites and structural optimization, instrument transformers can maintain stable external insulation under various harsh environments. This multi-dimensional design for preventing flashover is the foundation for ensuring accurate metering and safe operation of power systems.