Bulk Supply Pad Mounted Transformer Low MOQ Oil Immersed Distribution Power Transformer
Product Spotlights
- Hermetically Sealed Oil‑immersed Structure: Maintenance‑free, long service life for harsh sites.
- Low Loss & Low Noise: Adopts CRGO silicon steel for high energy‑saving performance.
- Strong Short‑circuit Withstand Capacity: Optimized winding design for reliable grid operation.
- Heavy‑duty Anti‑corrosion Enclosure: Salt‑spray resistant, ideal for PV, urban & industrial projects.
Bulk Supply Pad Mounted Transformer Low MOQ Oil Immersed Distribution Power Transformer
This factory‑direct pad‑mounted oil‑immersed distribution transformer comes with complete matching accessories. It supports multiple primary voltage options of 13.2kV,20kV,35kV, adopts hermetically sealed oil‑immersed construction, and delivers stable performance for outdoor distribution, urban construction and renewable‑energy projects.
1. Product Overview
Qinghao Three‑Phase Pad‑Mounted Oil‑Immersed Distribution Transformer is specifically engineered for modern power distribution networks, urban communities, commercial complexes, solar‑wind renewable energy projects and industrial sites. Designed to handle primary voltages from 10kV up to 35kV and secondary voltage of 0.4kV (custom voltage configurations available), with rated capacities ranging from 30kVA to 4000kVA.
This all‑in‑one unit integrates transformer core‑winding assembly, high‑voltage fuses, low‑voltage protection devices and switching components inside a heavy‑duty weather‑proof steel enclosure. Featuring a fully sealed corrugated oil tank design, the transformer oil is completely isolated from atmospheric air and moisture. This design prevents oil degradation, extends operational lifespan, eliminates routine oil maintenance, and ensures exceptional performance under severe outdoor environmental conditions. No separate transformer room is required for field installation.
2. Main Characteristics
Hermetically Sealed & Maintenance‑Free: The active part applies a core free‑hanging structure with high‑quality acrylate rubber gaskets to effectively inhibit aging caused by heat and sunlight. The oil tank uses corrugated sheets as thermal expansion elements, completely isolating the insulating oil from the atmosphere to prevent moisture and oxygen ingress.
Low Loss & Energy Efficiency: The magnetic core is built with high‑quality cold‑rolled grain‑oriented (CRGO) silicon steel sheets utilizing fifth‑order step‑lap stacking technology. This significantly reduces no‑load loss, no‑load current, and noise levels during operation.
High Short‑Circuit Resistance: High‑voltage windings are wound with high‑strength enamelled or paper‑insulated wire, while low‑voltage windings utilize high‑strength wire or copper foil. The uniform distribution of ampere‑turns and optimized insulation geometry provide superior capability to withstand electromagnetic short‑circuit forces.
Superior Anti‑Corrosion Enclosure Surface: The steel enclosure undergoes automated multi‑stage surface pretreatment‑including degreasing, pickling, phosphating, and electrophoresis‑followed by outdoor powder spray coating and high‑temperature curing. This ensures robust protection against salt spray, high humidity, and severe industrial corrosion for long‑term outdoor installation.
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Integrated Compact All‑in‑One Structure: Pre‑assembled with fuses and protection devices inside the cabinet. Space‑saving, direct outdoor ground mounting, fast on‑site commissioning without extra transformer building.
3. Technical Features & Performance Highlights
Standards Compliance: Fully designed, manufactured, and tested in strict accordance with IEC 60076, GB/T 1094, GB/T 6451, and IEEE / ANSI C57 standards.
Cooling System: ONAN (Oil Natural Air Natural) self-cooling system designed for continuous 100% full-load output under normal operating conditions.
Temperature Rise Limits: Winding temperature rise ≤ 65K, Top oil temperature rise ≤ 60K (under standard ambient conditions).
Voltage Tapping Range: Off-Circuit Tap Changer (OCTC) with ±2×2.5% or ±5% regulation range. On-Load Tap Changer (OLTC) is available upon request.
Insulation Levels: Fully insulated according to system voltage rating (e.g., LI75 AC35 for 10kV systems; LI200 AC85 for 35kV systems).
Vector Groups & Frequency: Standard Dyn11 or Yyn0 vector groups; 50 Hz or 60 Hz operating frequency.
4. Key Technical Specifications Table
| Parameter / Technical Item | Standard Specification & Custom Range |
| Rated Capacity Range | 30 kVA – 4000 kVA (Customizable) |
| Primary Voltage (HV) | 6kV, 10kV, 11kV, 15kV, 20kV, 33kV, 35kV (±2×2.5% or ±5%) |
| Secondary Voltage (LV) | 0.4kV, 0.415kV, 0.433kV, or custom request |
| Frequency | 50 Hz / 60 Hz |
| Phase & Vector Group | Three-Phase, Dyn11 / Yyn0 / Custom |
| Cooling Method | ONAN (Oil Natural Air Natural) |
| Core Material | High-permeability Cold-Rolled Grain-Oriented (CRGO) Silicon Steel |
| Winding Material | High-grade Electrolytic Copper / Aluminum Wire or Foil |
| Tank Type | Hermetically Sealed Corrugated Oil Tank |
| Compliance Standards | IEC 60076, GB/T 1094, GB/T 6451, IEEE/ANSI C57 |
5. Quality Control & Factory Routine Testing
Every single transformer undergoes rigorous routine testing before leaving our factory to ensure 100% operational reliability:
Winding Resistance Measurement
Voltage Ratio Inspection & Vector Group Verification
Impedance Voltage & Load Loss Measurement
No-Load Loss & No-Load Current Measurement
Separate-Source AC Voltage Withstand Test
Induced Overvoltage Withstand Test (DVDF)
Transformer Oil Dielectric Strength & Breakdown Voltage Test
6. Applications
Power Grids & Substations – Step up from generation voltage to transmission level, or step down to distribution voltage at substations.
Industrial Power Supply – Main and distribution transformers for steel mills, cement plants, mining, petrochemical, oil & gas facilities.
Commercial & Residential Distribution – Pole mounted or pad mounted units for rural electrification and urban underground networks.
Renewable Energy – Step up transformer for solar farms and wind power plants, converting inverter output (0.48kV/0.69kV) to medium voltage (10kV–35kV) or higher.
7. Frequently Asked Questions (FAQ)
Q1: Can you customize special voltage ratios or dual-voltage ratings (e.g., 13.8kV, 33kV, or 35kV)?
A: Yes, we provide full engineering customization for primary voltages from 6kV up to 35kV and various low-voltage outputs. Tap changers (OCTC or OLTC) can be tailored to your local grid requirements.
Q2: How is the transformer packaged for long-distance ocean freight?
A: Transformers are secured on heavy-duty wooden skids or fumigation-free wooden cases, wrapped in moisture-proof stretch film with desiccant, and rigidly anchored inside containers to prevent damage during transit.
8. Get a Custom Quote & Technical Drawing
Need a custom transformer design, technical datasheet, or CAD dimension layout for your project?
Contact our engineering sales team today to get a detailed technical proposal and a competitive quotation within 12 hours!
Please provide:
Rated power (kVA / MVA)
Primary and secondary voltages
Frequency (50Hz / 60Hz)
Vector group (Dyn11, Yyn0, etc.)
Tap changer type and range
Cooling method
Accessories required
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Installation environment (altitude, ambient temperature, humidity, corrosion level)
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