Instrument Voltage Transformer time-response to fast impulse

Instrument Voltage Transformers (VT) are well known for their critical behavior when subjected to fast impulse voltages. Furthermore, the accuracy of VT is defined by IEC Standards only at power frequency and doesn't consider fast impulse response. Under these conditions the VT may introduce errors in voltage measurements and the transmitted signals may create overvoltages in correspondence of the secondary circuitry and by nominal withstand. The paper reports experimental analysis on Instrument Voltage Transformers response, in time domain, to a fast voltage impulse (1.2/50 μs). The main experimental results on three commercial Instrument Voltage Transformers, having similar features but manufactured by different Producers, are presented and discussed. Also some considerations are reported considering the shielding effects of such components.