The Development Of Equipment To Detect The Electric Field Of Transformer Oil Gap Based On Kerr Effect

As one of the important equipments in HVDC system,converter transformer isdirectly related to the security of the entire transmission system. Compared with thenormal power transformer, the voltage of converter transformer withstand is morecomplex and its insulation system has higher requirement. The insulation structure ofthe converter transformer is oil-paper composite insulation.Studying the distributioncharacteristics of the electric field and space charge in a variety of voltages plays aimportant role.The purpose of this paper is to develop an equipment to detect theelectric field of transformer oil gap, provides a hardware foundation for investigatingthe electric field distribution and the characteristics of space charge distribution inconverter transformer.This paper has accomplished in-depth study of using the theory of keer effect todetect the electric field in transformer oil gap. The principle of measuring the electricfield in transformer oil under AC superimposed DC field has been also analyzed. Theoptical path and keer cell have been designed and manufactured. Using AC electricfield to modulate the photoelectric signal and the detection circuit has been designedto receive the photoelectric signal, meanwhile the whole equipment which is on thebased of keer effect to detect the electric field of transformer oil is fulfilled. Underdifferent proportions of AC superposed DC electric field, the electric field oftransformer oil gap has been measured by the set of equipment. The relationshipbetween the DC output signal, the fundamental output signal of photoelectric signaland the amplitude of the applied voltage has been Obtained. According to the testresults, this paper has further discussed the electric field in transformer oil, Thefeasibility of using the device this paper designed and manufactured to measure theelectric field in transformer oil is verified.