Experimental Study on the Wideband Response Characteristics of Electronic Current Transformers Using the Pulse Injection Method

This paper investigates the wideband transfer characteristics of electronic current transformers (CTs) using a pulse injection method. A high-voltage step pulse is applied to the primary side, and the voltage transfer function is estimated via frequency-domain analysis based on power spectral density. A dedicated test setup is developed to support wideband and high-amplitude excitation up to 100 MHz and 2000 V. Experimental results show that the transfer function increases with frequency, indicating a high-pass behavior. This behavior is attributed to the frequency-dependent decrease in core permeability, which reduces primary-side impedance. In addition, the transfer function also increases with excitation amplitude in the low-to-medium range but saturates under high excitation, reflecting core nonlinearity. These results suggest that electronic CTs may amplify high-frequency or high-amplitude interference, potentially worsening EMI propagation in fast-switching environments. The findings provide practical insights for modeling and EMI-aware design of current measurement systems.