CJEE

Chinese Journal of Electrical Engineering ›› 2024, Vol. 10 ›› Issue (1): 21-34.doi: 10.23919/CJEE.2023.000044

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Erosion Characteristics of Oil-immersed On-load Tap Changer Contacts Under Varying Contact Speeds and Pressures

Zongying Li1, Shuaibing Li1*, Yongqiang Kang1, Zheng Li2, Hongwei Li3   

  1. 1. School of New Energy and Power Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China;
    2. School of Electrical Engineering, Southwest Jiaotong University, Chengdu 611756, China;
    3. School of Automation and Electrical Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China
  • Received:2023-08-26 Revised:2023-09-05 Accepted:2023-09-11 Online:2024-03-25 Published:2024-04-10
  • Contact: * E-mail: lishuaibing1105@163.com
  • About author:Zongying Li received his B.Sc. degree in Electrical Engineering and Automation from Lanzhou University of Technology, Lanzhou, China, in 2021. Currently, he is working toward an M.Sc. degree in Electrical Engineering at the School of New Energy and Power Engineering, Lanzhou Jiaotong University. His main research focus are fault diagnosis and condition monitoring of power equipment.
    Shuaibing Li (Member, IEEE/CSEE) was born in Gansu, China in 1989. He received the Ph.D. in Electrical Engineering in 2018 from Southwest Jiaotong University. He is currently an Associate Professor with the School of New Energy and Power Engineering, Lanzhou Jiaotong University.
    His research interests include condition monitoring, assessment, fault diagnosis of high-voltage power equipment, and dynamic state estimation of electrical power systems.
    Yongqiang Kang (Member, IEEE) was born in Gansu Province, China, in 1988. He received B.Sc. and M.Sc. degrees in Electrical Engineering from Lanzhou Jiaotong University, Lanzhou, China, in 2008 and 2012, respectively. He received the Ph.D. degree in Electrical Engineering from Southwest Jiaotong University. He is currently an Associate Professor with the School of New Energy and Power Engineering, Lanzhou Jiaotong University. His research interests include high-voltage asset management, gas discharge and outdoor insulation detection.
    Zheng Li (Student member, IEEE) was born in 1994 and received his Master's degree in Electrical Engineering in 2021 from Lanzhou Jiaotong University. He is currently a Ph.D. student at the Southwest Jiaotong University. He is mainly engaged in research on condition assessment and nondestructive testing of high-voltage electrical equipment, and the detection and diagnosis of UHV power systems.
    Hongwei Li received Bachelor's, Master's, and Ph.D. degrees in Traffic Information Engineering Control from Lanzhou Jiaotong University, Lanzhou, China in 2003, 2009, and 2019, respectively. He is currently an Associate Professor with the School of Automation and Electrical Engineering, Lanzhou Jiaotong University, China. His research interests are in the areas of coordinated control of wind turbines and condition monitoring of power equipment.

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Abstract: With the growing demand for precise voltage adjustment and reactive regulation, the frequent operation of on-load tap changers (OLTCs) in oil-immersed systems has led to increased erosion of switch contacts by arcs during the switching process. This erosion causes significant wear on the contacts, thereby reducing their lifespan. Therefore, the present study aims to investigate the behavior and mechanism of arc erosion on contact surfaces in oil-immersed OLTCs. To achieve this, a self-designed friction and wear test device for OLTC contacts was utilized to conduct experiments at various sliding speeds and contact pressures. Additionally, finite element analysis was employed to validate the experimental results regarding the influence of sliding speed on arc energy. The surface morphology of the contacts was observed using an optical microscope. The findings revealed that as the sliding speed increased, the arc energy, arc initiation rate, and contact resistance initially exhibited an upward trend, then decreased, and eventually increased again. The minimum values were observed at a sliding speed of 90 mm/s. Moreover, the arc energy, arc initiation rate, and contact resistance decreased gradually as the contact pressure increased. After reaching a contact pressure of 1.5 N, the variation in the arc energy stabilized. At lower contact pressures, arc erosion dominated the wear on the contact surface. However, at higher contact pressures, the wear transitioned from predominantly arc erosion to a combination of mechanical wear and arc erosion. In summary, experimental and analytical investigations provided insights into the effects of sliding speed and contact pressure on the behavior of arc erosion, contact resistance, and surface damage of OLTC contacts in oil-immersed systems.

Key words: Oil-immersed on-load tap changer, arc energy, contact resistance, friction and wear, arc erosion