How Is The Primary Circuit Insulation Performance Of An Instrument Transformer Defined Using Epoxy Resin Insulators?

In the internal structure of current transformers or voltage transformers, the quality of the insulation components directly determines the service life of the entire device. While the dielectric constant of materials is frequently discussed, ultimately, the high voltage epoxy resin insulation in a transformer primarily serves as the primary circuit insulation to ground—its most basic and crucial function.

The Actual Stress Logic of the Insulation Structure

This material is directly positioned between the high-voltage side and the grounding shield. Normally, the high voltage discharged from the primary winding will constantly seek a leakage path, while the high voltage standoff in the current transformer mainly undertakes the insulation of the primary circuit to ground, and steadily locks this energy on the predetermined track. If the partial discharge of the material is not well controlled, this insulation layer will gradually carbonize.

• Electric Field Distribution Control: The geometric shape formed by mold casting disperses electric field stress.

• Crease Distance Design: Increasing surface wrinkles extends the current's travel distance in humid environments.

• Temperature Rise Withstand Capacity: Withstanding the heat generated by the coils during full-load operation to prevent deformation.

The Testing of Insulation Performance by the Operating Environment

During instantaneous power grid fluctuations, extremely high voltage pulses are generated. At this time, epoxy resin insulators in instrument transformers primarily serve as primary circuit insulation to ground, resisting the instantaneous pressure from lightning strikes or switching overvoltages. The adhesive strength and density of this material ensure that it will not break down due to internal air bubbles.

Often, field-reported faults point to insulation aging. This essentially comes back to the fundamental issue: since epoxy resin insulators primarily provide primary circuit insulation to ground in instrument transformers, any decrease in their hydrophobicity and pollution resistance will increase the leakage current to ground. The shrinkage rate parameter selected during material selection directly affects the stability of subsequent operation.