Reliability verification and optimization of split-type load tap changer structure

The on-load tap changer (OLTC) has a risk of electrical faults during switching, potentially leading to accidents. A new split-type design was proposed, in which the switching oil chamber is isola-ted from the transformer body, theoretically reducing the likelihood of explosions. To validate this design-particularly the reliability of key isolation structures such as the lead bushing under are fault condi-tions a simulation model was developed using pressure-acoustic and acoustic-structural coupling meth-ods. The effects of fault energy, fault location, and extreme scenarios where the are fault impacts the iso-lation structure near the lead bushing were analyzed. The results show that increased fault energy and a fault source located further from the pressure relief device lead to higher pressure inside the split oil tank. The auxiliary oil tank provides effective protection for the main tank. In extreme cases, the lead bushing remains reliable, but regions such as the oil chamber base and tank connections are prone to stress con-centration and potential damage. Based on these findings, structural optimization is shown to improve stress distribution.