Buried Transformer Section
The S11-MD buried transformer is a completely sealed underground substation engineered for installation in challenging environments such as pits, tunnels, and caissons, where space limitations and potential flooding pose challenges. With an IP68 waterproof rating, this underground distribution transformer efficiently converts 20kV, 10kV, or 6kV primary voltage to 0.4kV secondary voltage, ensuring robust power supply for road lighting, bridge systems, and underground infrastructure.
The transformer features a cold-rolled silicon steel core with mitered step-lap joints to minimize losses and magnetic noise, while cylindrical and spiral-wound coils provide exceptional mechanical durability. Its enclosure is crafted from durable A3 steel with an anti-corrosion coating for long-lasting performance even in immersed or polluted conditions.
- Completely sealed design allows for continuous submersion of up to 120 days under 1 meter of water.
- Primary voltage options: 6kV, 6.3kV, 10kV, 10.5kV, 11kV with adjustable ±5% or ±2×2.5% tapping range.
- Rated capacity ranges from 20kVA to 1600kVA, catering to diverse requirements for underground power distribution.
- Integrated plug-in cable connectors and current-limiting fuses on the high-voltage side enhance safety and efficiency.
- Low-voltage side incorporates a three-phase, four-wire plug-in connector for swift and secure connections.
Major Benefits and Features
Waterproof Rating (IP68)
Its fully sealed tank and watertight cable heads on both high-voltage and low-voltage sides ensure that the transformer is protected from moisture ingress even during prolonged submersion.
Low Loss Core Construction
Innovative cold-rolled silicon steel core and step-lap mitered joints reduce no-load current and magnetic noise, making it suitable for noise-sensitive environments.
Built-In Protection Using Fuses
High-voltage side features current-limiting fuses that provide short-circuit protection without requiring additional external switchgear.
Corrosion-Sealing Materials & Enclosure
The enclosure made of A3 steel with an anti-corrosion coating ensures resilience against high humidity, chemical exposure, and debris in underground conditions.
Space Efficient Pit Installation
Compact and optimized dimensions make it ideal for confined spaces like vaults, tunnels, and substation pits where above-ground setups are impractical.
Quiet Operation
Step-lap core technology reduces magnetostriction noise, making it suitable for installations in urban and residential underground locations.
Applications
Light for Roads and Bridges
Ideal for powering highway illumination, bridge accent lighting, and tunnel lighting systems, ensuring reliable operation even in challenging conditions.
Tunnel Infrastructure
Perfect for ventilation, signaling, and emergency lighting in road and rail tunnels that may face flooding risks.
Underground Parking and Basements
Provides streamlined power solutions for underground garages, commercial basements, and service areas requiring compact equipment.
Flood-Prone Remote Areas
Reliable power distribution in locations with high water tables, rural areas, and places prone to seasonal submersion.
Technical Specifications
S11-MD series buried transformer, 20kV/10kV/6kV underground substation, rated capacities 20–1600 kVA.
| Rated Capacity (kVA) | HV Voltage (kV) | LV Voltage (kV) | Connection | No-Load Loss (W) | Full-Load Loss (W) | No-Load Current (%) | Impedance (%) | Oil Weight (kg) | Total Weight (kg) | L × W × H (mm) |
|---|---|---|---|---|---|---|---|---|---|---|
| 20 | 6 / 6.3 / 10 / 10.5 / 11 ±5% or ±2×2.5% |
0.4 | Yyn0 or Dyn11 | 90 | 550/530 | 2.3 | 4 | 55 | 230 | 920×640×1350 |
| 30 | 100 | 630/600 | 2.1 | 4 | 75 | 305 | 950×700×1400 | |||
| 50 | 130 | 910/870 | 2.0 | 4 | 80 | 405 | 1000×750×1480 | |||
| 63 | 150 | 1090/1040 | 1.9 | 4 | 95 | 455 | 1030×815×1570 | |||
| 80 | 180 | 1310/1250 | 1.9 | 4 | 105 | 510 | 1040×850×1650 | |||
| 100 | 200 | 1580/1500 | 1.8 | 4 | 120 | 580 | 1090×880×1700 | |||
| 125 | 240 | 1890/1800 | 1.7 | 4 | 130 | 670 | 1110×930×1750 | |||
| 160 | 280 | 2310/2200 | 1.6 | 4 | 140 | 810 | 1110×960×1800 | |||
| 200 | 340 | 2730/2600 | 1.5 | 4 | 160 | 890 | 1200×960×1850 | |||
| 250 | 400 | 3200/3050 | 1.4 | 4 | 175 | 1020 | 1485×1000×1900 | |||
| 315 | 480 | 3830/3650 | 1.4 | 4 | 185 | 1170 | 1580×1050×1950 | |||
| 400 | 570 | 4520/4300 | 1.3 | 4 | 215 | 1410 | 1600×1100×2000 | |||
| 500 | 680 | 5410/5150 | 1.2 | 4 | 260 | 1645 | 1700×1150×2050 | |||
| 630 | 810 | 6200 | 1.1 | 4.5 | 310 | 2070 | 1800×1200×2100 | |||
| 800 | 980 | 7500 | 1.0 | 4.5 | 370 | 2445 | 1900×1250×2150 | |||
| 1000 | 1150 | 10300 | 1.0 | 4.5 | 425 | 2800 | 2000×1300×2200 | |||
| 1250 | 1360 | 12000 | 0.9 | 4.5 | 480 | 3320 | 2100×1400×2250 | |||
| 1600 | 1640 | 14500 | 0.8 | 4.5 | 550 | 4175 | 2200×1500×2300 |
Contact us for detailed underground transformer diagrams, technical PDFs, and wet-application load test reports.
Why Choose Our Buried Underground Transformers
Submersion Reliability
Undergoes rigorous pressure testing to ensure its ability to withstand 120 days of submersion before delivery.
Certified Quality
Routine testing for load capacities, insulation resistance, and voltage ratios per all IEC and IEEE standards is mandatory.
Competitive Pricing
Direct factory distribution allows cost-efficient procurement for bulk orders of underground transformers.
Fast Lead Times
S11-MD models are shipped in 3–5 weeks, with expedited configurations available for immediate needs.
Certifications & Standards
IP68 Rated
ISO 9001
GB 1094
CE
How This Buried Transformer Underground Substation Fits Your Project
Guidance specifically tailored for contractors, developers, EPCs, and distributors in underground power solutions.
Project Applications
The S11-MD underground transformer facilitates effective power distribution without above-ground structures, solving space constraints in Tunnel & Bridge Infrastructure. In Urban Basement & Parking Facilities, its compact dimensions enable discrete integration into confined areas. For Flood-Prone Distribution Networks, its 120-day submersion durability and waterproof design ensure reliable functionality.
S11-MD vs Standard Pad Mounted — Choosing the Right Product
Where underwater installation is required, the S11-MD buried transformer’s fully sealed waterproof connectors are a must-have compared to traditional pad-mounted units. Standard configurations meet requirements for surface setups while buried transformers excel in areas prone to water exposure.
Voltage & Capacity Selection
With adjustable primary voltages ranging from 6kV to 20kV and capacity options from 20–1600 kVA, these units cater to various loads, from small-scale lighting systems to extensive underground networks. Comprehensive project specifications can be obtained on request.
Frequently Asked Questions
What is a buried underground transformer?
A buried transformer (or underground substation) is a fully sealed distribution transformer designed for installation below ground level — in pits, vaults, or tunnels. Unlike pad-mounted units, it can operate while submerged under up to one meter of water for up to 120 days.
What is the difference between a pad-mounted transformer and an underground transformer?
Pad-mounted transformers sit on a concrete pad above ground, while underground distribution transformers are engineered for below-grade pits with IP68-rated sealed enclosures and waterproof cable connectors. The buried type suits flood-prone or space-constrained sites where above-ground units are infeasible.
What voltage options are available for your buried transformer underground substation?
Our S11-MD series covers 6kV, 6.3kV, 10kV, 10.5kV, and 11kV primary voltages with ±5% or ±2×2.5% tapping, stepping down to a 0.4kV secondary output.
Can the underground transformer operate continuously when submerged?
Yes. The fully sealed construction and waterproof HV/LV cable heads allow continuous operation even when completely submerged under one meter of water for up to 120 days.
Is the buried transformer suitable for residential areas?
Yes. Low magnetic noise from the step-lap core makes this underground residential transformer adaptable for neighborhoods where visible overhead equipment is undesirable and quiet operation is prioritized.
Can I obtain underground transformer diagrams and technical PDFs?
Yes. Contact us for detailed underground transformer diagrams, dimension drawings, load test reports, and complete S11-MD specification PDFs tailored to your project.
→ Request a Quote or Technical Datasheet for Your Buried Transformer
