Isolating switches are commonly used switching devices in power systems, and during their operation, the impact of arcs can generate strong high-frequency electromagnetic interference. This paper establishes an interference model for electronic voltage transformers during the switching process of isolating switches. It analyzes the interference magnitudes in key components of the transformer during this process. The study investigates the effects of internal parameters, including high-voltage arm capacitance, low-voltage arm capacitance, and parallel resistance, on the output waveform of the transformer. The interference magnitudes obtained provide a basis for the subsequent design of interference-resistant transformers.