Feasibility of E-Field Method for Faulty DC Insulators Live Detection

Researches on the DC power system were mainly focused on the equipments of power station in the past. Little attention was paid on the insulators, especially on the insulator live detection. In this paper, firstly, the component of DC insulator electric field is analyzed, then the feasibility of on-line detection of DC insulators by use of electric field method is discussed based on the investigating DC insulator electric field component distribution characteristic. Research results indecated the DC insulator electric field is composed by the DC electric field and harmonic electric field; DC electric field distribution curves were disorderly and unsystematic, it is easily influenced by external factors and isn't fit to detect faulty insulator; Harmonic electric field distribution is stabler and smaller influenced by external factors, it can effectively find out the internal short circuit defect in composed insulator and faulty porcelain insulator, harmonic electric field can be used to detect insulators.