Effect of O 2 on AC Partial Discharge and Decomposition Behavior of C 4 F 7 N/CO 2 /O 2 Gas Mixture.

This paper focus on the influence of oxygen on the partial discharge (PD) and decomposition characteristics of C 4 F 7 N/CO 2 /O 2 gas mixture as eco-friendly gas insulating medium. The PD characteristic parameters and phase resolved partial discharge (PRPD) patterns of C 4 F 7 N/CO 2 /O 2 gas mixture are, respectively, extracted and constructed. The influences of oxygen content and applied voltage on the PD and decomposition characteristics of C 4 F 7 N/CO 2 /O 2 gas mixture are investigated based on gas chromatography-mass spectrometry (GC-MS). We find that the addition of 2-4% O 2 to C 4 F 7 N/CO 2 gas mixture can significantly inhibit the negative half-cycle PDs and the generation of most by-products (CF 4 , C 2 F 6 , C 3 F 6 , CO, C 2 F 6 O 3 , CF 3 CN, C 2 F 5 CN, C 2 N 2). With the oxygen content higher than 6%, the accumulation discharge magnitude and discharge repetition rates of C 4 F 7 N/CO 2 /O 2 gas mixture increase sharply, accompanying the intensification of decomposition and deterioration of insulation strength. There is a positive correlation between the mean discharge magnitude and gas mixture decomposition intensity. To avoid the serious impact of PD fault on gas insulated equipment (GIE), the optimal oxygen addition in C 4 F 7 N/CO 2 /O 2 gas mixture should not exceed 6%. [ABSTRACT FROM AUTHOR]