Oil Immersed Power Transformer
Distinction note: This page focuses on substation grade oil immersed power transformers for transmission & sub transmission networks, different from low voltage distribution oriented three phase oil transformers for end user power supply. Oil immersed power transformers utilize transformer oil as both insulation and cooling medium, widely deployed for high voltage power transmission, substation step up / step down, renewable energy grid tie and heavy duty industrial power systems. Adopting fully sealed corrugated oil tank or conservator plus plate radiator structure, the unit isolates transformer oil from ambient air. This blocks moisture absorption and oxygen ingress, slows insulation aging and guarantees stable dielectric performance for long term field operation.
Description
Details page content
I. A brief product introduction
Oil immersed power transformers comprise three main assemblies: core functional units, tank & heat dissipation units, and connection & regulation units.
- Iron core and windings: Core functional components. They transform voltage and transmit isolated power through electromagnetic induction. CRGO grain-oriented silicon steel reduces no-load loss; copper windings ensure stable overload performance for continuous full-load operation at substations.
- Tank and insulating oil: Housing and cooling system. Insulating oil offers high dielectric insulation and effective heat dissipation. Mineral oil or high-flash vegetable ester oil is available for environmentally sensitive sites.
- Insulating bushings, on-load/off-load tap changers, gas relays, pressure relief valves and neutral-point protection assemblies: Connection & regulation parts for safe grid connection, flexible voltage adjustment and multi-parameter fault protection.
Different from distribution transformers designed for fluctuating light end-user loads, this power transformer series is developed for nearly continuous full-load service in transmission substations. The 110kV version features reinforced insulation, enhanced cooling and complete neutral-point overvoltage protection.
II. Model Explanation
III. Product Details/Advantages
1. High‑Performance Core‑Winding & Graded Insulation System
Adopting high-grade CRGO silicon steel core and copper windings with graded insulation, together with high-dielectric transformer oil to prevent partial discharge and breakdown for 10kV–110kV operation.
2. Fully‑Sealed Construction Option
Sealed corrugated tank keeps out moisture and oxygen to cut maintenance and extend service life; conservator type is available for large MVA units.
3. Modular Thermal Management ONAN / ONAF Dual‑Rating
ONAN natural cooling and ONAF forced-air cooling deliver enhanced peak load capacity, with optimized radiators maintaining stable temperature under continuous full-load operation.
4. Safety & Environmental Compliance
Optional biodegradable vegetable insulating oil for eco-sensitive areas. Multi-protection system includes gas relay, pressure relief valve, winding temperature monitoring and 110kV neutral-point overvoltage protection.
5. Custom‑Engineered for Transmission‑Grid Conditions
Custom built for grid fluctuations, high altitude, coastal salt fog and heavy pollution, with optimized external insulation, anti-corrosion coating and impulse withstand levels based on site surveys.
IV. Product Parameters
|
Item |
Specification |
|
Operating Ambient Temperature |
‑20 °C ~ +40 °C (wider range for special cold‑climate customization) |
|
Relative Humidity |
≤85 % @20 °C; anti‑condensation design for high‑humidity sites |
|
Altitude |
≤1000 m standard; reinforced‑insulation version for altitude >1000 m |
|
Standard Temperature‑Rise Limit |
Oil top ≤55 K; Winding ≤65 K (per IEC 60076) |
Our oil immersed power transformer can be equipped with stick gap and MOA combined neutral‑point overvoltage protection to meet global grid anti‑accident requirements.
V. Scope of Supply
|
No |
Name |
Model |
Qty |
Unit |
|
1 |
Oil‑immersed power transformer |
Per project specification |
1 |
Set |
|
2 |
Installation accessories, radiators, conservator, accessories kit |
Matched with main unit |
1 |
Set |
VI. Optional Customization Solutions
Beyond standard spec power transformers, our core advantage is engineering oriented customization for transmission grade projects. Our technical team analyzes your grid condition, substation layout, environmental constraints (salt fog, high altitude, low temperature), short circuit withstand requirements and neutral point protection scheme. We deliver fully tailored oil immersed power transformer solutions rather than off the shelf general purpose products. We aim to be your long term reliable heavy electrical equipment partner for global substation and renewable energy projects.
VII. Quality
At Rsafele Electric, a rigorous quality culture means that we systematically control the entire production process and strictly adhere to written quality control plans.
Qualification association: We adhere strictly to globally recognized regulations and protocols, integrating environmental excellence and quality management throughout the product lifecycle.
VIII. Real-world cooperation cases
Comoro 3×40 MVA Substation Project, East Timor
We delivered customized 40 MVA 110kV‑class oil‑immersed power transformers for main‑grid power‑supply requirements. Adapted to local grid‑voltage fluctuation conditions. The transformer adopts high‑flash‑point eco‑friendly insulating oil compliant with local environmental‑regulations, integrates fault‑recording module to support remote equipment‑status monitoring.
IX. Application Scenarios
- Transmission & Sub‑Transmission Substations: Main‑grid backbone equipment for step‑up / step‑down power conversion in utility‑owned substations (10kV‑110kV voltage levels).
- Renewable‑Energy Power Plants: Step‑up transformer for large‑scale onshore wind farms & solar‑PV stations to feed bulk power into high‑voltage grid.
- Heavy‑Duty Industrial Power Systems: Metallurgy, mining, petrochemical large‑plant internal main‑substation, handling large‑capacity continuous industrial load.
- Large‑Scale Commercial & Public‑Utility Infrastructure: Regional central power‑supply hub for large industrial parks, new‑city comprehensive energy stations.
X. Our Service
Our after-sales service and technical team solemnly promises
Pre-Sales Service
- Consultation & Guidance: 24/7 online support with expert engineers to clarify needs, recommend solutions, and advise on pricing and processes.
- On-Site Inspection: Engineers visit sites for precise measurements and environmental assessment, deliver detailed reports to support tailored system design.
After-Sales Service
Year Warranty: Covers material/manufacturing defects as per contract.
Dedicated Support: One-on-one follow-up from a specialized team for seamless assistance.
Multi-Channel Help: Support via contacts, project teams, or website; fast global coordination for repairs or replacements during warranty.
XI. Product usage tutorials, solutions, and technical problem notifications
Oil Immersed Power Transformer Pre Operation Checklist (Substation Grade)
• I. Visual & sealing inspection (tank, radiator, bushing, conservator, sealing gaskets)
• II. High voltage electrical safety verification (insulation resistance test, ratio test, neutral point protection device inspection for 110kV units)
• III. Insulating oil & cooling system check (oil level, oil quality test, fan circuit test for ONAF cooling)
• IV. Long term key maintenance rules for substation operation scenario
[Click here to view the complete product manual & detailed instructions >]
XII. Packaging and Transportation
XIII. Factory Strength
1. Qualification Certificates
2. Innovative technologies/capabilities
(1) High-tech enterprise certificate
3. Supply Chain Advantages
- 1. Mature Raw Material Supply with Cost & Delivery Control: Ample domestic supply of bulk materials (silicon steel, magnet wire, transformer oil) with diverse suppliers gives manufacturers stable pricing power and ensures production continuity.
- 2. Localization of Key Components Boosts Supply Chain Autonomy: High-end components previously reliant on imports are gradually localized, reducing external dependence, procurement risks, and strengthening industrial chain self-control.
- 3. Well-Developed Industrial Clusters with High Collaborative Efficiency: Regional clusters around transformer production, with complete supporting facilities from core processing to insulation and oil tanks, shorten procurement/logistics cycles and improve supply chain responsiveness.
4. Professional production equipment (CNC)
XIV. FAQ
1. Q: How to identify and handle dehumidifier malfunctions?
A: Identify malfunctions when silica gel turns pink, the oil cup is empty, or the unit is clogged. Caused by saturated silica gel, low oil level, or blockages. Immediately replace with dry blue silica gel, refill the oil cup to cover the breather port, and clear any airway obstructions.
2. Q: What should be done after the pressure relief valve activates?
A: Indicated by a ruptured diaphragm, oil spray, and loud noise. Typically caused by internal faults or a failed diaphragm. Shut down immediately, inspect for internal faults, replace the diaphragm with a certified one, and verify its set pressure meets specifications.
3. Q: What are the signs of winding faults and how to handle them?
A: Signs include >2% 3-phase voltage imbalance, >5% DC resistance deviation, and a sharp insulation resistance drop, possibly with crackling sounds or gas relay activation. Root causes are insulation aging or breakdown. Execute an immediate shutdown, prohibit re-energizing, perform diagnostic tests, and arrange factory repair for rewinding.
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