Space charge behavior in multi-layer oil-paper insulation under different DC voltages and temperatures

TLDR

Oil‑paper insulation is widely used in power transformers and cables, its dielectric properties are critical, yet space‑charge formation and dynamics can degrade insulation performance. This study investigates space‑charge behavior in oil‑paper insulation using the pulsed electroacoustic (PEA) technique. Measurements were performed under varying DC voltages and temperatures to characterize space‑charge evolution. Results show homocharge injection occurs under all conditions, with DC voltage primarily influencing the amount of space charge, while temperature significantly affects its distribution and mobility.

Abstract

Oil-paper as a reliable insulation system is widely used in power transformers and cables. The dielectric properties of oil-paper insulation play an important role in the reliable operation of power equipment. However, the formation and dynamics of space charge can affect the performance of insulation material. In this paper, space charge in oil-paper insulation system has been investigated using the pulsed electroacoustic (PEA) technique. A series of measurements were carried out when the insulation system was subjected to different applied voltages at different temperatures. Charge behavior in the insulation system has been analyzed and the influence of temperature on charge dynamics was discussed. The test results show that homocharge injection takes place under all the test conditions, the applied dc voltage mainly effect the amount of space charge, while the temperature has greater influence on the distribution and mobility of space charge inside oil-paper samples.