The drive spring serves as the sole energy source during the switching process of on-load tap changer (OLTC). It is subject to repeated compression and release

posing risks of fatigue failure and performance degradation

which makes it necessary to study the effect of its relaxation performance on the switching reliability of OLTC. This paper focuses on the drive spring of OLTC. Firstly

this paper elucidates the working process of the drive spring

studies a rigid flexible coupling method and an identification method of oil damping based on experimental data to optimize the dynamic model of OLTC. Secondly

it conducts a fatigue performance tests on springs under working conditions

and concludes that the spring relaxation rate and the logarithm of vibration frequency is linearly correlated. Thirdly

it explores the influence of spring relaxation on the dynamic characteristics and electrical performance of OLTC based on simulation optimization and experimental data. The research can provide useful references for the parameter design and condition assessment of the OLTC.