- Model: S11 / S13 / S20 / S22
- Rated capacity: 15–31500 kVA
- Service voltage: 6 / 11 / 20 kV
- Cooling: ONAN
- Sealed, conservator-free design
The S20 Series Oil-Immersed Distribution Transformer is a fully-sealed, high-efficiency power distribution solution engineered for modern utility, industrial, and commercial applications. It combines a low-loss core design that complies with national energy-efficiency standards with a robust corrugated tank construction that eliminates the need for an external conservator. The result is a compact, maintenance-reduced transformer built to perform reliably in demanding environments.
This transformer is designed for customers who prioritize energy savings, low maintenance, and long service life—key decision factors for U.S. utilities, data centers, renewable energy projects, and industrial facilities.
Key Features
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Fully-Sealed Design – No external conservator required; the corrugated tank accommodates oil expansion and contraction internally.
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Low-Loss Core – Meets or exceeds national energy-efficiency standards (e.g., DOE 2016 / IEEE C57.12.00 efficiency levels).
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Corrugated Tank Construction – Enhances sealing integrity and weather resistance; ideal for harsh, humid, or coastal environments.
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High Sealing Performance – Prevents oil leakage and moisture ingress, reducing maintenance and environmental risk.
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Weather-Resistant Finish – Coated for UV, corrosion, and temperature resistance for outdoor installation.
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Compact Footprint – Space-saving design suitable for pad-mount, pole-mount, or vault installations.
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Low Noise Operation – Optimized core and tank design for reduced audible noise.
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Long Service Life – Designed for 20–30+ years of reliable operation with minimal intervention.
Technical Specifications (Typical Range)
| Parameter | Specification |
|---|---|
| Type | Oil-immersed, fully-sealed distribution transformer |
| Series | S20 |
| Rated Capacity | 30 kVA – 2,500 kVA (custom ranges available) |
| Primary Voltage | 2.4 kV – 34.5 kV (typical) |
| Secondary Voltage | 120/240 V, 277/480 V, 347/600 V, etc. |
| Frequency | 50 Hz / 60 Hz |
| Phase | Single-phase and three-phase |
| Cooling Method | ONAN (Oil Natural Air Natural) |
| Impedance | 4% – 6% (standard) |
| Efficiency | Meets DOE 2016 / NEMA TP-1 / IEEE C57.12.00 |
| Insulation Class | A / E / B (depending on configuration) |
| Temperature Rise | 55°C / 65°C (standard) |
| Tap Changer | Off-circuit tap changer (typically ±2 × 2.5%) |
| Tank Material | Corrugated steel, coated for corrosion resistance |
| Cooling Fluid | Mineral oil or environmentally friendly ester oil |
| Protection | Sealed tank, pressure relief valve, optional Buchholz relay |
| Standards | IEEE, ANSI, NEMA, DOE, UL (as applicable) |
Applications
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Utility Distribution – Overhead and pad-mounted distribution networks.
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Commercial Buildings – Shopping centers, office complexes, hospitals.
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Industrial Facilities – Manufacturing plants, warehouses, mining operations.
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Renewable Energy – Solar farms, wind turbine step-up/step-down stations.
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Data Centers – Reliable, low-loss power distribution for critical loads.
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Infrastructure – Airports, railways, water treatment plants.
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Residential Developments – Community distribution in harsh climates.
Benefits for U.S. Customers
Energy Efficiency & Cost Savings
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Lower no-load and load losses reduce electricity costs over the transformer’s life.
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Complies with DOE 2016 efficiency standards and supports utility rebate programs.
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Ideal for states with strict energy codes (e.g., California, New York, Washington).
Reliability & Maintenance
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Fully-sealed design minimizes oil oxidation and moisture ingress.
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No conservator means fewer components to inspect or maintain.
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Corrugated tank reduces stress on seals and gaskets.
Environmental & Safety
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Reduced risk of oil leakage; optional ester oil for biodegradable operation.
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Pressure relief and fault protection options available.
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Quiet operation suitable for residential and urban installations.
Installation Flexibility
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Compact and lightweight compared to traditional conservator-type transformers.
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Suitable for pad-mount, pole-mount, and vault installations.
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Corrosion-resistant finish for coastal, desert, and humid environments.
Frequently Asked Questions (FAQ)
Q1: What makes the S20 Series different from traditional oil-immersed transformers?
A1: The S20 Series uses a fully-sealed corrugated tank that eliminates the external conservator. This reduces maintenance, improves sealing, and enhances weather resistance while maintaining low-loss performance.
Q2: Does the S20 Series meet U.S. energy efficiency standards?
A2: Yes. The S20 Series is designed to comply with DOE 2016 efficiency requirements and can be configured to meet NEMA TP-1, IEEE C57.12.00, and applicable UL standards.
Q3: Can the S20 Series be used in coastal or humid environments?
A3: Absolutely. The corrugated tank and corrosion-resistant coating provide excellent protection against moisture, salt spray, and temperature extremes.
Q4: What cooling method does the S20 Series use?
A4: Standard cooling is ONAN (Oil Natural Air Natural). Other cooling classes (ONAF, OFAF) can be provided for higher capacity or specialized applications.
Q5: Is an external conservator required?
A5: No. The corrugated tank design accommodates oil expansion and contraction internally, eliminating the need for a conservator.
Q6: What voltage classes are available?
A6: Typical primary voltages range from 2.4 kV to 34.5 kV, with secondary voltages from 120 V to 600 V. Custom configurations are available.
Q7: What oil is used in the S20 Series?
A7: Standard mineral oil is used, but environmentally friendly ester oil (FR3 or equivalent) is available for applications requiring biodegradability and higher fire safety.
Q8: How long is the expected service life?
A8: With proper installation and minimal maintenance, the S20 Series is designed for 20–30+ years of reliable service.
Q9: Can the S20 Series be used for renewable energy projects?
A9: Yes. It is well-suited for solar and wind applications, including step-up and step-down configurations, due to its low losses and robust sealing.
Q10: What certifications are available?
A10: The S20 Series can be supplied with UL, CSA, IEEE, and DOE compliance documentation. Specific certifications depend on the configuration and destination market.
