Prediction of the Progressive Loss of Winding Clamping Pressure in Power Transformers. (18th February 2020)

• Record Type: Journal Article
• Authors: Gao, Shuguo; Zhao, Jun; Meng, Lingming; Liu, Hongliang
• Other Names: Nguyen-Thanh Nhon Academic Editor.
• Is Part Of: Mathematical problems in engineering. Volume 2020(2020)
• Publication Date: 2020-02-18
• Subjects: Engineering mathematics -- Periodicals; 510.2462
• DOI: 10.1155/2020/6315239
• Languages: English
• ISSNs: 1024-123X

Abstract

Abstract : This paper investigates the progressive loss of winding clamping pressure resulted from thermal aging in power transformers. Firstly, out-of-plane stress-strain characteristics of aging pressboards are investigated experimentally and relationship between mechanical properties of pressboards and aging hours is established accordingly. Then, a thermal-mechanical model is built to correlate the aging time with temperature based on the first-order reaction kinetics. Based on the above investigations, the correlation between temperature and mechanical properties of pressboards is obtained and the progressive loss of clamping pressure is predicted. The results show that with the progressive softening of pressboards from aging, the clamping pressure drops linearly under 60°C and nonlinearly over 60°C. The remaining clamping pressure of a transformer winding with 30 years' service history is only 80.12% and 51.59% of its initial pressure under 50°C and 60°C, respectively.