Impulse-voltage measurement of distribution-class surge arresters by D-dot probes

This article presents the design and testing of two D-dot probes to measure residual voltages of surge arresters, namely, coaxial toroidal and radial conical types. Both probes were terminated by high impedance to measure the voltage directly, and a corona-free design was checked by calculating the electric-field profiles inside the test module. Simultaneous impulse-voltage measurements were conducted by using two designed D-dot probes, two uncompensated commercial mixed resistive-capacitive probes, and an uncompensated damped capacitive-voltage divider. The linearity of the two D-dot probes was checked for unloaded and loaded conditions by linear resistors and surge arresters. Residual voltage measured for an 11-kV and 33-kV surge arrester by two commercial mixed resistive-capacitive probes and the capacitive-voltage divider showed longer rise time, an initial inductive overshoot superimposed on the waveform, and a significant decay even before the current peak instant, contrary to those measured by the designed two D-dot probes.