30kV–33kV–35kV Oil-Immersed Off-Circuit Tap-Changing Power Transformer

The 30kV–33kV–35kV oil-immersed distribution transformer is a three-phase, two-winding distribution transformer with rated high voltages of 30kV, 33kV, 35kV, or 38.5kV, a rated low voltage of 0.4kV (380V/220V), and mineral transformer oil serving as both the insulating and cooling medium. Designed primarily for AC 50/60Hz power systems, it transforms and distributes medium- and high-voltage power down to low-voltage levels, serving as the critical link between the regional grid and end users.

1. Low Losses The core is made of premium, high-permeability cold-rolled silicon steel, slit longitudinally and transversely on a Swiss fully automated core-cutting line and assembled by fully automated stacking with multi-step fully mitred joints. The core is bound using integral pressurization and PET-band banding, effectively reducing the transformer's no-load losses and no-load current.

2. Low Noise The noise of a oil-immersed self-cooled transformer is mainly caused by the electromagnetic noise of the core. To reduce this noise, our company has taken the following measures: a low-flux-density design, premium high-permeability silicon steel, advanced equipment from both domestic and international suppliers, fully automated robotic stacking for precise control of stacking accuracy, and reliable clamping and bracing structures combined with special vibration-damping measures.

3. Leak-Free The tank and conservator undergo both positive- and negative-pressure leak tests to ensure no oil leakage occurs during normal operation. Components are mounted using a flanged-groove structure, and all seals use acrylate rubber parts from well-known domestic and international brands to prevent oil seepage.

4. Off-Circuit Tap Changer The off-circuit tap changer is sourced from well-known domestic and international brands and undergoes rigorous incoming electrical inspection and mechanical interlock testing to ensure reliable operation.

5. Short-Circuit Withstand Capability To ensure the transformer can withstand the impact of short-circuit currents without any thermal or mechanical damage, our company has adopted the following measures in design and manufacturing:

a. Reasonable ampere-turn balance calculations are performed on the transformer windings, using semi-hard copper wire.

b. The core clamping components undergo strength and rigidity calculations to meet the safety requirements for short-circuit mechanical forces.

c. The winding-spacer pressboard is densified and made from high-density board, while the wooden parts use high-insulation laminated wood.

d. The windings are clamped using a structure of uniformly distributed pressure blocks, ensuring even force distribution during assembly and safeguarding short-circuit withstand capability.

This product complies with GB/T1094 Power Transformers, GB/T 6451-2023 Specification and Technical Requirements for Oil-Immersed Power Transformers, GB 20052-2024 Permissible Values of Energy Efficiency and Energy Efficiency Grades for Power Transformers, and IEC 60076 Power Transformers.