Abstract
Natural esters, as the renewable resources, offer excellent physiochemical and dielectric properties such as the fire-resistance, high biodegradability and satisfactory dielectric breakdown performance. Thus, natural esters are selected as the insulation and heat dissipation medium for electrical equipment. However, the electrical performance of natural esters with different structures under the long gap and higher electrical stress needs further evaluations. In this paper, streamer propagation of various natural esters under the long gap and higher electrical stress were observed optically. The influence of voltage polarity, liquid types and gap distances on streamer characteristics of natural esters were analyzed. Results show that the maximum propagation velocity of streamer in natural esters is greater than that in the hydrocarbon liquids. Breakdown voltage of natural esters under negative polarity is much higher than that under positive polarity for the same gap distance. Among all the natural esters concerned, the camellia liquid demonstrates slower streamer velocity and slight greater lightning breakdown voltages for the positive and negative polarity. The lower content of unsaturation triacylglycerol molecules in camellia liquid contributes to the inhibition of ionization and streamers propagation. Results would be valuable reference for the design, manufacture and operation of the electrical equipment filled with natural ester.
Highlights
Zhengyong Huang,1,2,a Xiuping Chen,[1] Jian Li,1,a Feipeng Wang,[1] Ruiqi Zhang,[1] Muhammad Ali Mehmood,[1] Suning Liang,[1] and Tianyan Jiang3 1State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing 400040, China 2Postdoctoral Research Station on Chemical Engineering and Technology, Chongqing University, Chongqing 400040, China 3Chongqing University of Technology, Chongqing 400040, China (Received 3 September 2018; accepted 15 October 2018; published online 25 October 2018). Dielectric liquids, such as hydrocarbon liquids and natural esters are widely used in transformers, capacitors, cables, and switchgear, with the function to prevent or rapidly quench electric discharges happening in these electrical devices.[1]
Electric field change when streamer development. It has been proven in our previous study that for natural esters, there is a negative correlation between the concentration of unsaturated triacylglycerol molecules and the ionization potential (IP) and electron affinity (EA) because of plentiful of C=C double bonds in triacylglycerol molecules
This paper presents streamer propagation characteristics and breakdown phenomenon in natural esters and hydrocarbon-based liquid under lightning impulse voltage
Summary
Wang et al proposed that the presence of cellulose particles in the insulating liquid may lead to reduced breakdown voltages in synthetic ester liquids and this may be attributed to the advancement in streamer initiation in these liquids.[33] In addition, comparative analysis and studies on the streamer propagation and the breakdown properties of synthetic esters and natural esters were studied to predict breakdown voltage of esters at very large gaps.[34,35,36] the research about the streamer discharge in natural esters with different chemical structures under long gap distances have been rarely reported. Results would be valuable reference for the design, manufacture and operation of the electrical equipment filled with natural ester
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
