When evaluating qualified Power Transformer suppliers, engineering teams frequently debate: Should we prioritize oil-immersed or dry-type technology for our primary substation? The choice hinges on fault current levels, maintenance protocols, and site conditions. Oil-immersed transformers, with their high thermal capacity and superior dielectric strength, are the undisputed workhorses for utility-scale step-up/down applications. However, their performance relies heavily on the integrity of the internal insulation system and the tank's ability to withstand internal arc pressure.
Lugao’s oil-immersed units are built to excel under these mechanical and electrical duress. Our proprietary core clamping and winding techniques ensure that even under a sudden 2.5% reactance deviation during a fault, the windings remain perfectly aligned. This mechanical ruggedness, validated through rigorous short-circuit withstand tests (exceeding 20kA RMS), is what differentiates a durable Power Transformer from a liability.
Unlike standard distribution transformers that handle moderate loads, a high-voltage Oil-Immersed Transformer must manage the intense heat generated by continuous load currents. Cyclic load variations cause localized overheating on core joints and winding conductors, which accelerates oil degradation and paper insulation embrittlement. Lugao eliminates this vulnerability through specific material selection and processing.
Our transformers feature high-grade cold-rolled grain-oriented silicon steel (27QG120) with step-lap joints and stress-relief annealing. This metallurgical precision ensures no-load losses remain strictly within IEC 60076 standards. For the windings, we utilize oxygen-free copper conductors wrapped in premium kraft paper, employing a continuous helical winding technique. This is followed by a stringent vacuum drying process that removes residual moisture, effectively eliminating partial discharge (PD) risks that commonly plague inferior units.
|
Internal Component |
Material/Technique |
Performance Indicator |
Failure Prevention |
|
Core Laminations |
27QG120 Silicon Steel + Step-Lap Joints |
No-Load Loss ≤ Standard IEC 60076 |
Prevents core saturation & flux leakage hotspots |
|
Windings |
Oxygen-Free Copper + Helical Winding |
Dynamic Short-Circuit Withstand ≥ 2.5% Reactance Deviation |
Eliminates winding buckling under sudden fault currents |
|
Tank Structure |
Q345R Steel + Robotic Welding |
Leak Rate Zero (24-Hour Submersion Test) |
Prevents oil seepage and rupture under internal arc pressure |
|
Oil-Insulation System |
Mineral Oil / Natural Ester + Vacuum Filling |
Breakdown Voltage ≥ 60kV |
Prevents partial discharge & accelerates heat dissipation |
Exposed to weather, dust, and potential impacts, the tank structure serves as the primary defense. Lugao oil-immersed power transformers achieve IP44 protection ratings with anti-corrosion surface treatments, capable of withstanding coastal salt spray and extreme ambient temperatures. The heavy-duty tank (Q345R) is robotically welded and pressure-tested at 0.3 MPa, guaranteeing zero leakage and maintaining structural integrity for decades.
Lugao’s SGS-certified facility supports full-power test bays and professional core-cutting lines, manufacturing in strict compliance with IEC, GB, CE, and CCC standards.
· 132kV / 110kV Step-Up/Step-Down Transformer: Designed for utility substations and power plant grid-connection. Adopts a robust oil-immersed tank with ONAN or ONAF cooling, featuring exceptionally low partial discharge (≤ 5 pC) and superior short-circuit withstand capability.
· 33kV / 35kV Power Transformer: Ideal for wind farm collection systems and heavy industrial zones. Balances high efficiency with a compact footprint, offering flexible cooling options and customizable voltage taps.
· 11kV Distribution Transformer: Suitable for commercial complexes and rural electrification. Features a corrugated oil tank design that eliminates the need for a conservator, ensuring reliable operation in harsh outdoor environments.
· ONAN: Relies on natural convection for moderate load applications.
· ONAF: Augments natural oil circulation with forced air fans, increasing overload capacity by approximately 30%.
· OFAF: Deploys forced oil circulation with forced air heat exchangers for maximum heat dissipation.
For large-scale substations, conventional units with external radiators work best. However, for urban underground substations, Lugao offers customized footprint optimization, reducing overall floor space requirements by utilizing integrated radiator panels without sacrificing cooling efficiency.
Experience Lugao's Power Transformer manufacturing excellence firsthand:
