Question & Answer

Oil-immersed transformers dominate power systems primarily due to the following advantages:

Superior Insulation and Heat Dissipation: The dielectric strength of insulating oil is much higher than that of air, allowing for more compact winding designs. Furthermore, the efficient convective circulation of the oil, combined with external radiators or corrugated tanks, grants it far better cooling capacity than dry-type transformers. This makes it ideally suited for high-capacity, high-voltage applications.

High Reliability and Long Service Life: In a sealed environment, the insulating oil effectively prevents moisture ingress and oxidation of the windings. Their design life typically exceeds 20-30 years, ensuring stable and reliable operation.

Strong Overload Capacity: Thanks to the high thermal capacity of the oil and the efficient cooling system, they can withstand significant short-term overloads.

Cost-Effectiveness: For equivalent voltage ratings and capacities, their manufacturing cost is generally lower than that of dry-type transformers, offering better value in large-scale transmission and distribution projects.

Consequently, they are primarily deployed in grid substations, power plant step-up stations, and industrial distribution—scenarios that require handling high voltage and large power while balancing space and cost considerations.

The choice between oil-immersed and dry-type transformers fundamentally stems from the different insulating and cooling mediums, which lead to a series of practical distinctions.

Manufacturing a high-performance, highly reliable oil-immersed transformer represents the pinnacle of power equipment technology. The key requirements include:

Core Materials and Manufacturing Processes:

Core Technology: Use of high-permeability, low-loss grain-oriented silicon steel sheets. Precision stacking (step-lap) and laser/mechanical cutting ensure tight joints to minimize no-load loss.

Winding Technology: Use of oxygen-free copper conductors and techniques like transposed conductors to reduce eddy current losses. Windings must be wound tightly and uniformly, undergoing rigorous drying and oil impregnation to eliminate partial discharge.

Insulation and Temperature Rise Control: Insulation System Design: Establishment of a scientific oil-paper composite insulation system with precise electric field distribution to ensure extremely low partial discharge levels (typically required <100 pC).

Cooling Structure Design: Optimization of oil ducts and radiator/corrugated panel layout to achieve efficient heat transfer, keeping the winding and oil temperature rise within standard limits.

Sealing and Reliability:

Hermetic Sealing Technology: Ensuring long-term, absolute sealing of all tank and bushing interfaces to prevent moisture and air ingress, which degrade oil and performance. This is critical for transformer longevity.

Factory Tests: Must pass a full suite of routine and type tests far exceeding operational standards, including lightning impulse, temperature rise, and short-circuit withstand capability tests (verifying dynamic and thermal stability).

Intelligence and Environmental Considerations: Condition Monitoring: Integration of intelligent sensors such as fiber-optic temperature sensors and Dissolved Gas Analysis (DGA) online monitors for predictive maintenance.

Environmental Requirements: The use of high-fire-point, biodegradable synthetic ester insulating oils is a growing trend in high-end models, enhancing safety and environmental friendliness.

Boda, short for Boda Precision Electromechanical Technology Co., Ltd. (based in Zhongshan City, China), has a core connection with oil-filled (oil-immersed) transformers as a key manufacturer of oil tank assemblies for large-scale power transmission and distribution oil-immersed transformers in China.

Our oil tank products are critical core components for oil-immersed transformers, responsible for housing the transformer core and windings, containing insulating oil, and ensuring structural stability and heat dissipation. Key technical parameters and features of our oil tanks include:

Material Selection: Mainly adopt high-quality cold-rolled carbon steel (Q235B/Q355B) for standard applications; customized stainless steel (304/316) options for corrosive environments (e.g., coastal or chemical industrial zones).

Manufacturing Processes: Utilize CNC bending, precision plasma cutting, and submerged arc welding (SAW) for seamless joints; all welds undergo helium leak testing to ensure 100% sealing performance (leak rate ≤ 10⁻⁶ mbar·L/s).

Anti-Corrosion Treatment: Multi-layer coating system (shot blasting or phosphatization → epoxy primer → polyurethane topcoat) with thickness ≥ 120μm, meeting ISO 12944 C5 corrosion resistance standards for outdoor long-term use (service life ≥ 20 years).

Structural Design: Optimized ribbed plate layout for enhanced mechanical strength (able to withstand internal pressure up to 0.15MPa); integrated oil conservator connection and temperature control interfaces for compatibility with full-range transformer cooling systems (ONAN/ONAF/OFAF).

These tanks are supplied to major downstream transformer manufacturers, who integrate them into complete oil-immersed transformer products and export to over 10 countries/regions worldwide. Our key customers in the transformer industry include:

TBEA (TBEA Co., Ltd.)

CRRC (China Railway Rolling Stock Corporation)

GE VERNOVA (General Electric VERNOVA)

Eaglerise (Guangdong Eaglerise Electronics Co., Ltd.)

MINGYANG Electric (Guangdong Mingyang Electric Co., Ltd.)

SUNTEN Electric (Guangdong Sunten Electric Co., Ltd.)

COMKING Electric (Foshan Comking Electric Co., Ltd.)

Keyuan Electric (Guangdong Keyuan Electric Co., Ltd.)

In summary, Boda is a vital upstream supplier in the oil-immersed transformer industry chain, specializing in high-quality, technically optimized oil tank production to support global transformer manufacturing and power infrastructure projects.