Abstract: A system and method for monitoring or testing dielectric material nondestructively and in situ within field-based electrical equipment or as samples in a laboratory environment. In exemplary embodiments the use of negative voltage test pulses and a ground plane electrode with a parabolic curve or ogive shape minimizes energy transferred to the dielectric material to avoid or minimize degradation of the material. The disclosed system and method are thus suitable, inter alia, for continuous or near-continuous monitoring of fluid-filled electrical equipment in the field.