66/110/220/330kV Eco Design Power Transformer

110kV Transformers

• Concepts: 110kV transformers are high-voltage (HV) step-down units typically operating in regional transmission and sub-transmission networks. They bridge the gap between high-voltage bulk power grids and lower-voltage industrial or urban distribution systems (such as 35kV or 10kV).

• Applications: Widely used as step-down substations to supply power to medium-to-large industrial facilities, urban substations, and regional load centers. They also serve as interconnection transformers in moderately sized generation plants.

• Applicable Scope: Urban and suburban power grids, large manufacturing plants, chemical processing facilities, heavy commercial complexes, and regional sub-transmission substations.

220kV Transformers

• Concepts: 220kV transformers function as primary backbone components in regional and inter-provincial power transmission grids. They feature high insulation levels, large capacity ratings, and advanced cooling systems designed to handle substantial bulk power transfers over medium to long distances.

• Applications: Utilized in major regional step-down substations to convert ultra-high or high-voltage power down to 110kV or 66kV levels. They are crucial for stabilizing grid voltage, managing heavy industrial loads, and integrating conventional power plants (thermal, hydro, or large wind/solar farms).

• Applicable Scope: Provincial backbone power grids, metropolitan ring transmission networks, large-scale renewable energy collection stations, and heavy industrial economic development zones.

330kV Transformers

• Concepts: 330kV transformers are specialized extra-high-voltage (EHV) units engineered primarily for transmission networks characterized by high altitudes, long-distance power conveyance, and specific geographic topologies.

  Applications: Deployed to transmit bulk electrical energy efficiently over vast geographic expanses with minimal line losses. They handle heavy interchange between major regional grids and step down EHV power to lower transmission tiers (such as 220kV or 110kV).

• Applicable Scope: Predominantly utilized in specific regional power grids—notably in Northwest regions and high-altitude areas with extensive transmission distances—as well as major inter-regional tie-lines and ultra-large-scale generation integration hubs.

330kV Oil-Immersed Three-Phase Double-Winding Off-Circuit Tap-Changing Power Transformer

330kV Oil-Immersed Three-Phase Three-Winding Off-Circuit Tap-Changing Power Transformer

220kV Oil-Immersed Three-Phase Double-Winding Off-Circuit Tap-Changing Power Transformer

220kV Oil-Immersed Three-Phase Three-Winding Off-Circuit Tap-Changing Power Transformer

220kV Oil-Immersed Three-Phase Double-Winding On-Load Voltage Regulating Power Transformer

220kV Oil-Immersed Three-Phase Three-Winding On-Load Voltage Regulating Power Transformer

110kV Oil-Immersed Three-Phase Double-Winding Unexcited Voltage Regulating Power Transformer

110kV Oil-Immersed Three-Phase Three-Winding Unexcited Voltage Regulating Transformer

110kV Oil-Immersed Three-Phase Double-Winding On-Load Voltage Regulating Power Transformer

110kV Oil-Immersed Three-Phase Three-Winding On-Load Voltage Regulating Power Transformer

66kV Oil-Immersed Three-Phase Double-Winding Unexcited Voltage Regulating Power Transformer

66kV Oil-Immersed Three-Phase Double-Winding Unexcited Voltage Regulating Power Transformer

Quality Assurance & Core Process：

1. High-Permeability Grain-Oriented Electrical Steel

We utilize Hi-B high-permeability grain-oriented (HPGO) electrical steel—the same grade specified by TBEA and CHINT—as the transformer core material, with standard nominal thicknesses of 0.23 mm and 0.27 mm. Core laminations are manufactured using high-precision cutting equipment to guarantee a burr height of ≤0.02 mm. The assembly incorporates a precision step-lap lamination structure, maintaining optimal clamping pressure without imparting excessive mechanical stress to the electrical steel, combining high-B steel characteristics with an optimized magnetic flux density.

2. High-Conductivity Winding Conductors & Core-Coil Assembly

High-conductivity electrolytic copper or aluminum conductors are selected based on transformer capacity, voltage class, and loss requirements. Incoming materials undergo stringent quality inspections for dimensions, electrical resistance, surface quality, and traceability. During the winding process, conductor tension, winding height, layer insulation, and conductor positioning are precisely controlled to ensure resistance consistency and mechanical stability, thereby minimizing load losses and temperature rise during operation.

During core-coil active part assembly, coil height, axial clamping force, radial support, and spacer block positioning are precisely controlled. Proper mechanical clamping prevents coil displacement during transport, normal operation, and short-circuit conditions. Meanwhile, clamping forces are strictly regulated to avoid excessive stress on conductors and insulation materials. Our mechanical design accounts for both radial and axial electromagnetic forces, safeguarding short-circuit withstand capability and long-term dimensional stability.

3. Advanced Insulation System (Oil-Immersed & Dry-Type)

For oil-immersed transformers, we utilize high-grade insulation materials, including Kraft paper, thermally upgraded paper, pressboard, and transformer-grade laminated board. For dry-type transformers, we employ DMD, NMN, Nomex, fiberglass, and epoxy resin systems. Insulation thickness, overlap width, oil duct dimensions, electrical clearances, and mechanical positioning are strictly regulated. All insulation materials are stored under climate-controlled conditions to minimize moisture absorption and contamination, ensuring stable dielectric strength and long-term insulation reliability.

4. Controlled Vacuum Drying

We apply a controlled drying curve regulated by temperature, vacuum level, and duration parameters, rather than relying on fixed cycle times. The process comprises controlled pre-heating, evacuation, primary drying, and final soak phases, with continuous temperature and vacuum monitoring and logging. End-point determination is based on validated process criteria and moisture limits. This process minimizes residual moisture in cellulose insulation, maximizing dielectric strength, retarding insulation aging, and extending overall service life.

5. Vacuum Epoxy Resin Casting

For cast-resin dry-type transformers, we utilize controlled vacuum casting technology. Resin-to-hardener ratio, material temperature, vacuum level, mixing time, pouring conditions, and curing temperatures are strictly regulated. Vacuum degassing minimizes micro-voids prior to pouring, while controlled curing ensures stable mechanical and thermal properties. Finished coils undergo thorough visual and electrical inspections, including routine partial discharge (PD) testing. This process eliminates internal voids, ensuring reliable insulation performance throughout the transformer's service life.

6. Clean Assembly & Torque Control

Final assembly takes place in a controlled environment to minimize contamination from dust, metallic particles, and foreign objects. Critical components are inspected for cleanliness, dimensional accuracy, and insulation condition. Electrical clearances, lead routing, grounding connections, and mechanical supports are rigorously controlled throughout assembly. Critical bolted joints are tightened to specified torque values using calibrated equipment and fully logged. Prior to sealing the tank or enclosure, a thorough internal inspection ensures no tools, loose parts, or foreign material remain.

7. 100% Factory Routine Testing

Every transformer undergoes 100% routine testing prior to dispatch, complying with applicable IEC standards, approved technical specifications, and customer requirements. Standard test routines include winding DC resistance, voltage ratio, vector group verification, no-load loss and current, load loss and short-circuit impedance, applied voltage withstand, and induced overvoltage withstand tests. Special tests—such as partial discharge (PD), dissipation factor (tan δ), or sweep frequency response analysis (SFRA)—are conducted upon request. Each unit is assigned a unique serial number linked to its material records, manufacturing data, and final test reports, ensuring end-to-end traceability.

Youth Transformer Co.,Ltd.