Influence of glucose as a contaminant on discharge characteristics of HVAC insulator

• Published in: IEEE transactions on dielectrics and electrical insulation Vol. 23; no. 1; pp. 394 - 402
• Main Authors: Yang, Shuai, Zhou, Wenjun, Yu, Jianhui, Zhou, Chengke, Hu, Hui, Wang, Baoshan, Yang, Cuiru
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.02.2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Contaminants; Contamination; discharge; Discharges (electric); Electric discharges; Electric potential; Glucose; Insulation; Insulators; Leakage currents; Mathematical analysis; Moisture; Moisture absorption; molecular dynamics; Pollution; quantum chemistry; Sugar; Surface chemistry
• ISSN: 1070-9878; 1558-4135
• DOI: 10.1109/TDEI.2015.005177

Contaminant is the main factor affecting the insulation performance. The contaminant composition determines the inception voltage and the intensity of insulation discharge. This paper studies the intense discharge activity at low humidity (77% RH) in AC 500 kV Gangcheng substation where the contaminant contained glucose, and this phenomenon was rarely explained in previous publications. Electrical and chemical performances of glucose as a contaminant on insulation surface were investigated by means of discharge test (below 80% RH), artificial pollution test (100% RH), molecular dynamics simulations, and quantum chemistry calculations. The experimental results show that due to stronger moisture absorption capacity compared to non-glucose contaminant, glucose contamination sample has lower discharge inception voltage and stronger discharge intensity at 75% RH as the content of glucose exceeds 0.10 mg/cm 2 . Quantum chemical calculations reveal that the glucose molecules can decompose to generate free radicals with the unpaired electrons under the strong electric fields. The surface carbonation enhances the electron transfer rate and strengthens the discharge intensity. Moreover, the competitive adsorption of glucose and water molecules cause the low moisture discharge phenomenon, and it needs to be considered for insulation design and maintenance in areas producing sugar.