1kV/1.2kV/2.4kV/3.3/kV/4.16kV Oil-immersed Distribution Transformer

Youth Transformers utilize premium-grade cold-rolled grain-oriented electrical steel (exclusively sourced for CHINT and TBEA) to reduce core operating magnetic flux density. Featuring 45° full-mitered step-lap joints with rigorous control over shearing burrs and optimized yoke clamping pressure, the cores undergo stress-relief annealing post-shearing. Magnetic shielding and flux barriers are implemented on core clamping structures, tie plates, and frames. Furthermore, winding heights and radial dimensions are meticulously engineered and verified through real-time testing. Collectively, these advanced measures reduce no-load current by an average of 60% to 80% and no-load losses by 25% to 35%, ensuring full compliance with IEC 60076 standard loss classes.

Youth Transformers adopt a hermetically sealed tank design, featuring bolted or welded tank-to-rim joints. All sealing interfaces—including rims, flanges, inspection manholes, and bushing flanges—utilize oil- and aging-resistant nitrile rubber (NBR) or fluoroelastomer (FKM) gaskets to prevent leakage caused by the premature degradation of standard rubber. Comprehensive corrosion protection is applied to both internal and external tank surfaces, complemented by an oil-resistant anti-corrosion coating on the interior walls and 100% nondestructive examination (NDE) of all tank welds. High thermal-class insulating paper (such as Nomex) and high-density pressboard are employed throughout. Utilizing high-grade naphthenic transformer oil with excellent oxidation stability, the hermetically sealed environment drastically suppresses oil oxidation rates. These integrated engineering practices significantly extend the operational lifespan of the transformer.

4.16 kV (Widely used industrial and commercial MV step-down rating in North American and IEEE-standard facilities)

3.3 kV (Standard secondary distribution level for mining equipment, industrial pumps, and power plant auxiliaries)

2.4 kV (Specialized industrial primary distribution level and legacy municipal system rating)

1.2 kV (Utilized for solar PV string step-up transformers and low-medium industrial applications)

1.0 kV (1000 V) (Boundary MV/LV insulation threshold rating for specialized industrial and mining transformers)

35kV Oil-Immersed Three-Phase Double-Winding Unexcited Voltage Regulating Power Transformer

35kV Oil-Immersed Three-Phase Double-Winding On-Load Voltage Regulating Power Transformer

10kV Oil-Immersed Three-Phase Double-Winding Unexcited Voltage Regulation Distribution Transformers

10kV Oil-Immersed Three-Phase Double-Winding On-Load Regulating Distribution 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. This design leverages the properties of high-B steel combined with optimized magnetic flux density.

2. High-Conductivity Winding Conductors

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.

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. Transformer Oil Processing & Vacuum Filling

We use transformer oil compliant with applicable IEC or ASTM standards, testing each incoming batch. Processing includes filtration, dehydration, and degassing performed via vacuum purification units. Key parameters—including breakdown voltage, moisture content, dissipation factor (tan δ), and neutralization value (acidity)—are tested in accordance with relevant standards. Traceability is maintained through batch logging and processing records, minimizing moisture, dissolved gases, and particulate contamination within the insulation system.

Following drying, controlled vacuum oil filling is performed to minimize trapped air and prevent re-absorption of ambient moisture into the insulation. Dehydrated and degassed transformer oil is injected under controlled vacuum and temperature conditions. All gaskets, flanges, valves, radiators, bushings, and conservator joints undergo meticulous inspection. The fully assembled tank undergoes leak, pressure, or vacuum testing per applicable standards to ensure long-term integrity against oil leakage and moisture ingress.

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.