Unlike standard distribution transformers that handle only medium-voltage conversion, Power Transformer solutions must contend with two conflicting demands: they must step generator output voltage up to transmission levels—or step down high-voltage, high-capacity power to distribution levels—while simultaneously withstanding the immense electromagnetic forces and short-circuit current surges generated during grid faults.
Conventional winding structures are prone to deformation or even collapse under sustained radial electromagnetic forces, potentially triggering sudden inter-turn short circuits and catastrophic failure. Our custom-engineered units feature an optimized core clamping system, high-strength insulating board, and a rigid tank structure. This design achieves complete decoupling of axial and radial electromagnetic forces, effectively preventing winding displacement and excessive hotspot temperature rise. Thanks to this optimized mechanical design, Lugao power transformers offer a service life extension of up to 28% under long-term, continuous, heavy-load transmission conditions.
When auditing qualified Power Transformer suppliers, utility engineering teams should focus on core material selection, winding technique, and integral insulation coordination. Cyclic load variations during long-run transmission easily cause localized overheating on core joints and winding conductors, further accelerating oil degradation, paper insulation embrittlement, and irreversible dielectric breakdown.
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Internal Component |
Base Material Selection |
Core/Winding Treatment |
Performance Indicator |
Primary Failure Prevention |
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High-Permeability Core Laminations |
High-Grade Cold-Rolled Grain-Oriented Silicon Steel (27QG120) |
Step-Lap Joint & Stress-Relief Annealing |
No-Load Loss ≤ Standard IEC 60076 |
Prevents core saturation and flux leakage hotspots |
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Precision-Wound HV/LV Windings |
Oxygen-Free Copper Conductors + Premium Kraft Paper Insulation |
Continuous Helical Winding & Vacuum Drying |
Dynamic Short-Circuit Withstand ≥ 2.5% Reactance Deviation |
Eliminates winding buckling under sudden fault currents |
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Heavy-Duty Tank Structure |
High-Strength Structural Steel (Q345R) |
Robotic Welding & Pressure-Tight Testing (0.3 MPa) |
Leak Rate Zero (24-Hour Submersion Test) |
Prevents oil seepage and tank rupture under internal arc pressure |
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Advanced Oil-Insulation System |
High-Grade Mineral Oil or Biodegradable Natural Ester Fluid |
Vacuum Oil Filling & Hot-Oil Circulation Drying |
Breakdown Voltage ≥ 60kV (IEC 60156) |
Prevents partial discharge and accelerates heat dissipation |
Lugao Power Co., Ltd. owns an ISO9001 and SGS-certified production workshop, equipped with professional core cutting lines, winding machines, vacuum drying ovens, and full-power test bays. All products are manufactured in strict accordance with IEC, GB, CE, and CCC international standards, supporting direct plug-and-play replacement without modifying original substation layouts.
Lugao develop multiple Power Transformer Voltage classes to match different transmission levels and distribution network requirements:
· 132kV / 110kV Step-Up/Step-Down Power Transformer: Designed for large utility substations, power plant grid-connection systems, and heavy industrial zones requiring bulk power transmission. Adopting a robust oil-immersed tank structure with ONAN or ONAF cooling, It features exceptional short-circuit withstand capability and extremely low partial discharge levels (≤ 5 pC), while facilitating the inspection and maintenance of bushings and tap changers.
· 33kV / 35kV Power Transformer: Suitable for mid-size industrial plants, wind farm collection substations, and campus distribution networks. It balances high efficiency with compact footprint, offering flexible cooling options and customizable voltage taps to accommodate grid voltage fluctuations.
· 11kV Distribution Power Transformer: Ideal for commercial complexes, residential communities, and rural electrification projects. It features a corrugated oil tank design that eliminates the need for an oil conservator, thereby reducing maintenance frequency and ensuring reliable operation in harsh outdoor environments.
All Lugao Transformer units offer flexible cooling configurations to optimize thermal performance based on site conditions:
· ONAN (Oil Natural Air Natural): Relies on natural convection for cooling—ideal for moderate load applications where ambient conditions are favorable.
· ONAF (Oil Natural Air Forced): Augments natural oil circulation with forced air cooling fans, increasing continuous overload capacity by approximately 30%.
· OFAF (Oil Forced Air Forced): Deploys forced oil circulation with forced air heat exchangers, enabling maximum heat dissipation for high-capacity Power Transformer installations in demanding environments.
Power Transformer selection needs to comprehensively consider site space constraints, load growth projections, and grid fault level requirements. For traditional large-scale substations with abundant floor space, conventional three-phase oil-immersed units with external radiators are the preferred solution. They handle uniform electromagnetic stress distribution, and maintenance crews can inspect bushings and tap changers easily without de-energizing adjacent equipment.
For urban underground substations and compact GIS (Gas-Insulated Substation) installations, lower-profile designs with integrated radiator panels are more applicable. Lugao offers customized footprint optimization, reducing overall floor space requirements by up to 15% while maintaining consistent power handling capacity and cooling efficiency to meet modern urban grid expansion demands..
Components used in Lugao transformers effectively address two common operational issues: excessive oil temperature rise and uncontrolled partial discharge (PD). Prolonged exposure to high-voltage stress and continuous load currents generates significant copper and iron losses, leading to a decline in the dielectric strength of the insulating oil and the deterioration of inter-winding insulation; this, in turn, triggers partial discharge and gas accumulation, potentially resulting in catastrophic flashover incidents.
Our exclusive built-in hot-oil circulation and vacuum drying process, combined with a high-efficiency radiator bank, continuously circulates and cools insulating oil. It stably controls top-oil temperature below 75°C during 24-hour continuous full-load operation (ambient temperature ≤ 40°C), maintains complete dielectric protection for winding paper insulation, stabilizes internal gas equilibrium, and avoids localized discharge and oil decomposition caused by hotspot accumulation.
Experience Lugao's Power Transformer manufacturing excellence firsthand:[Click here to watch our full production tour on YouTube]
· [10KV Amorphous Alloy Dry Type Transformer] — Ideal for energy-efficient indoor distribution applications.
· [33kV 35kV Oil-Immersed Transformer] — Robust mid-voltage solution for industrial and renewable projects.
· [132kV 110kV 50MVA 125MVA Oil Immersed Transformer] — High-capacity backbone for utility transmission networks.
Sources: Lugao Power Co., Ltd. official technical documentation and IEC-standard certified test reports.
