In recent years

the frequent occurrence of decay-like failures of composite insulators has become a severe issue threatening the safe and stable operation of power systems. These failures are often caused by the development of internal defects in insulators. Traditional detection methods suffer from susceptibility to environmental interference and low detection efficiency

which are not conducive to effective defect identification. This paper proposes a new method for detecting internal conductivity defects in composite insulators based on electroluminescence (EL). Firstly

distortion characteristics of insulator surface electric field with internal defects are analyzed through a finite element model to characterize the internal state of the insulators. Experiments show that ZnS:Cu electroluminescent (EL) composite materials can achieve luminescence response under high electric field conditions when excited by high-energy electron transitions and ultraviolet photons

which are also suitable for the service conditions of insulators. Samples of electroluminescent self-diagnostic composite insulators with internal conductivity defects are fabricated in the laboratory. Charging tests verify that the electroluminescent method can achieve self-identification of internal conductivity defects in insulators

and has high shape fidelity for defects. Finally

a comparative analysis is conducted to reveal the superiority of the proposed method over traditional detection methods. The results show that the proposed method can effectively identify composite insulators with conductivity defects situated within the blind zones of traditional methods

indicating promising application prospects.