The 35kV oil-immersed power transformer is an indispensable core device in electric power systems, undertaking the critical functions of voltage conversion, power transmission, and distribution. As the hub connecting high-voltage transmission networks with medium- and low-voltage distribution grids, 35kV oil-immersed power transformers are widely used in urban and rural distribution networks, industrial parks, new energy power generation, mining and manufacturing enterprises, and commercial buildings. Xinhong Electrical (Jiangsu Xinhong Electrical Equipment Co., Ltd.) has long been dedicated to the R&D and manufacturing of power equipment, committed to providing customers with efficient and reliable 35kV oil-immersed power transformers and integrated solutions. This article systematically elaborates on the core technical aspects of 35kV oil-immersed power transformers from three dimensions: product characteristics, application scenarios, and operation maintenance specifications.
35kV oil-immersed power transformers excel in energy saving and loss reduction. The core is made of high-permeability, high-quality oriented cold-rolled silicon steel sheets, combined with a fully mitered lamination method, effectively reducing no-load loss and no-load current. The S-series products adopt new core designs and optimized winding structures, achieving a reduction of no‑load loss by over 20% and load loss by over 10% compared with conventional transformers. The products meet the energy efficiency requirements of the national standard GB 20052‑2020.
Xinhong Electrical strictly complies with GB/T 6451‑2023 Technical Parameters and Requirements for Oil-Immersed Power Transformers in the manufacturing of its 35kV oil‑immersed power transformers, ensuring that every transformer achieves the highest possible efficiency through meticulous material selection and process control.
In structural design, 35kV oil-immersed power transformers employ several advanced technologies: high-voltage windings adopt multi-layer cylindrical and continuous structures to improve impulse voltage distribution; low-voltage windings use cylindrical or helical structures, offering high mechanical strength, balanced ampere‑turn distribution, and strong short‑circuit withstand capability. The tank is of the bell‑type design, equipped with an expansion oil conservator, effectively ensuring operational safety.
The products are manufactured with a vacuum oil‑impregnation process, completely eliminating bubbles inside the windings to guarantee long‑term insulation performance stability. All fasteners are fitted with locking nuts to prevent loosening during extended operation. Xinhong Electrical's 35kV oil‑immersed power transformers undergo strict factory acceptance tests before delivery to ensure safe and reliable performance.
35kV oil-immersed power transformers use high‑quality silicon steel sheets and optimised magnetic circuit designs, significantly reducing noise levels to meet modern urban and residential environmental requirements. The insulating oil is made of recyclable, environmentally friendly materials, and the product materials are reusable. The excellent sealing performance achieves leak‑free, maintenance‑free operation. The fully sealed design effectively isolates the transformer oil from air contact, slowing oil degradation and insulation aging.
Modern 35kV oil-immersed power transformers already support “four‑remote” functions – remote signaling, remote measurement, remote adjustment, and remote control – enabling computer‑based remote supervision and making unattended substation operation feasible. By collecting key data such as temperature, current, voltage, and vibration from the transformer, online power quality analysis and fault early warning can be realised. Xinhong Electrical keeps pace with intelligent trends and offers 35kV oil‑immersed power transformer solutions that can integrate intelligent monitoring systems, tailored to customer needs.
35kV oil-immersed power transformers are the main power transformation equipment in small and medium‑sized substations, widely used in urban and rural distribution networks. The S‑series products are specifically designed for high efficiency, low noise, and high reliability, making them an ideal choice for main transformers in regional substations.
In industrial parks and mining/manufacturing enterprises, 35kV oil-immersed power transformers serve as the primary power supply equipment for load centres, demanding extremely high short‑circuit withstand capability and operational reliability. Their capacity range typically covers 50 kVA to 40,000 kVA, meeting the power demands of various enterprise scales.
With the rapid growth of the new energy industry, 35kV oil-immersed power transformers are increasingly applied in photovoltaic, wind power, and energy storage projects. This series accurately matches the main scenarios of new energy applications and is a core supporting power equipment for integrated wind‑solar‑storage projects. Dedicated transformers for wind farm unit substations and photovoltaic step‑up transformers extensively adopt 35kV oil‑immersed designs.
35kV oil-immersed power transformers are widely used in commercial buildings, high‑rise structures, airports, subways, tunnels, offshore platforms, and other important facilities. Xinhong Electrical provides customised solutions to meet the special technical requirements of different scenarios.
Installation of 35kV oil-immersed power transformers shall strictly comply with applicable standards such as GB/T 6451 and DL/T 572. Before installation, the quality of the insulating oil, explosion‑proof devices, and cooling system must be inspected. For oil‑immersed transformers equipped with a gas relay, the top cover shall be installed with a slope of 1%–1.5% along the oil flow direction towards the gas relay.
Before commissioning, verify that the nameplate voltage rating matches the line voltage, check that all components are correctly installed, and confirm that the voltage, temperature, and sound are normal during no‑load operation.
Patrol inspections for 35kV oil-immersed power transformers should be systematic and standardised:
Daily inspection: At least once per day; for critical locations, every 2 hours. Mainly check the tank and seals for oil leakage, and verify that the oil level gauge reading is within the normal range (typically between 1/4 and 3/4 of the oil gauge).
Periodic inspection: A comprehensive inspection is recommended once per quarter, using professional tools such as thermometers and insulating oil testers.
Special inspections: Additional inspections should be conducted during sudden weather changes, overload operation, or other special conditions.
Inspection contents include transformer temperature and oil quality, insulating bushings, busbars, breather desiccant, grounding protection equipment, and operating sound.
Routine maintenance should keep the transformer exterior clean, promptly removing oil stains and dust on high‑ and low‑voltage bushings to prevent surface discharge in humid conditions. Regular insulation testing and tap‑changer adjustments should be performed.
Oil quality management is crucial for oil‑immersed transformers. Periodic dissolved gas analysis (DGA) of transformer oil should be conducted to determine the internal insulation condition by detecting dissolved gases in the oil. For transformers of 35kV and above, it is recommended to install online DGA monitoring systems.
When abnormal sounds, excessive temperature rise, abnormal oil level, gas relay operation, or other anomalies occur, immediate inspection and corrective actions shall be taken. For forced‑oil circulation cooling systems, two independent power supplies must be provided, with automatic and manual changeover capability.
Xinhong Electrical recommends that users establish complete equipment files, recording operation parameters, maintenance history, and test data, enabling full life‑cycle management of the transformer.
With outstanding characteristics such as high efficiency, structural reliability, low noise, and intelligent readiness, the 35kV oil‑immersed power transformer plays an irreplaceable role in electric power systems. From urban and rural distribution networks to new energy generation, and from industrial parks to infrastructure, its application fields continue to expand. Proper installation, systematic inspection, and timely maintenance are the key safeguards for ensuring long‑term safe and stable operation of 35kV oil‑immersed power transformers.
Xinhong Electrical (Jiangsu Xinhong Electrical Equipment Co., Ltd.), as an integrated enterprise spanning R&D, manufacturing, trade, and service, consistently adheres to technology‑driven innovation and customer‑oriented solutions. We are committed to providing global customers with high‑quality 35kV oil‑immersed power transformers and comprehensive power solutions. For more product information or technical support, please visit the Xinhong Electrical official website or contact our technical service team.
