The SZ4000/35 is a 35kV-class two-winding oil-immersed vacuum on-load tap-changing main transformer, with the built-in Tenrony SYJZZ vacuum on-load tap changer. It performs continuous automatic voltage regulation under load without any power interruption, solving the bus voltage deviation (high/low) caused by day/night and seasonal load fluctuations, and keeping the low-voltage side stable within the national standard range. It is the primary voltage-stabilizing supply equipment for 35kV substations, new-energy booster stations and large industrial plants.