30–2500kVA S13-M Oil-Immersed Distribution Transformer

The S13-M Fully Sealed Oil-Immersed Distribution Transformer is engineered by JiangSu Dingxin Electric as a next-generation, low-loss replacement for the legacy S11 series. It uses a fully oil-filled sealed (omniseal) corrugated oil tank that is permanently sealed yet has built-in elasticity to accommodate the thermal expansion of the insulating oil, removing the need for a separate conservator and providing maintenance-free long-term operation.

Compared with the S11, the S13-M series achieves an average 30% reduction in no-load loss and an average 5% reduction in load loss, delivering significant energy savings across its service life. The transformer is equipped with a pressure relief valve (activates at 35 Kpa) and, for units of 800 kVA and above, signal thermometers and gas relays for full protection.

Model Naming Convention (S13-M):

• S — Three phases

• 13 — Performance level code (Series 13, latest generation)

• M — Omniseal (fully sealed) construction

• Advanced Winding Structure — Optimized winding design improves electrical performance, reduces stray losses, and supports stable operation under varying load conditions.

• Strong Mechanical and Shock Resistance — Robust winding clamping and tank structure deliver high short-circuit withstand capability, ideal for networks with frequent switching transients.

• Excellent Drying and Insulation — Premium insulating oil combined with a fully sealed tank prevents moisture ingress, keeping the dielectric strength stable over decades of service.

• Optimized Tank Design — Corrugated fin oil tank provides a large radiating surface area, enabling effective natural oil cooling (ONAN) and silent operation.

• Maintenance-Free Operation and Long Lifespan — Fully sealed construction eliminates oil contact with outside air, removing the need for routine oil sampling, drying or filtering.

• Comprehensive Protective Service — Pressure relief valve (activates at 35 Kpa) for fault pressure release and alarm; signal thermometers and gas relays fitted to all units of 800 kVA and above, providing temperature tripping/alarm and light/heavy gas alarm.

Voltage Combination & Connection

Loss Specifications (19 Standard Ratings, S13 Series)

Compliance Standards

• IEC 60076-1 — Power transformers — General

• IEC 60076-3 — Insulation levels, dielectric tests and external clearances

• IEC 60076-5 — Ability to withstand short circuit

• IEEE C57.12.00 — General requirements for liquid-immersed distribution, power, and regulating transformers

• IEEE C57.12.90 — Test code for liquid-immersed distribution, power, and regulating transformers

• ANSI C57.12.10 — Safety requirements for transformers 600 V and below

Regular Service Conditions

• Installation: Indoor or outdoor

• Altitude: ≤ 1000 m

• Maximum ambient temperature: +40°C

• Maximum daily mean temperature: +30°C

• Maximum annual mean temperature: +20°C

• Minimum air temperature: −25°C

• Custom designs available for special operating conditions on request.

Energy-Saving Performance vs. S11

• No-load loss: Reduced by an average of 30% compared to S11 series (per IEEE C57.12.00 / IEC 60076 / IEC 50588)

• Load loss: Reduced by an average of 5% compared to S11 series (per IEEE C57.12.00 / IEC 60076 / IEC 50588)

EC 60076-1/3/5

IEEE C57.12.00

IEEE C57.12.90

ANSI C57.12.10

• Urban & rural distribution networks — 10 kV pole-mounted or pad-mounted distribution substations.

• Industrial plants — Manufacturing facilities, mining operations and process lines requiring reliable medium-voltage step-down.

• Commercial complexes — Shopping malls, office parks, hotels and large residential developments.

• Renewable energy — Solar / wind step-up auxiliary transformers and grid-connection distribution.

• Infrastructure projects — Airports, railway stations, ports, highways, water treatment plants.

• Remote & harsh-environment sites — Oil and gas fields, offshore platforms, desert and high-altitude installations (special versions on request).

• Replacement of legacy S7/S9/S11 units — Direct, low-loss drop-in replacement for network upgrades.

Q1. What is the difference between the S13-M and the S11 series? The S13-M series reduces no-load losses by an average of 30% and load losses by an average of 5% compared with the S11 series, both referenced to IEEE C57.12.00, IEC 60076 and IEC 50588.

Q2. What is the capacity range of the S13-M transformer? The S13-M series covers rated capacities from 30 kVA to 2500 kVA, with 19 standard power ratings.

Q3. What does "fully sealed" (omniseal) mean? The S13-M uses a fully oil-filled sealed design with a corrugated oil tank. The permanently sealed tank has its own elasticity to accommodate the thermal expansion of the oil, eliminating the need for a conservator and providing maintenance-free long-term operation.

Q4. Does the S13-M have a pressure relief device? Yes. When the internal pressure reaches 35 Kpa due to an internal fault, the pressure relief valve automatically activates to release pressure or send an alarm. When the pressure returns to normal, the transformer resumes normal operation.

Q5. What protective devices are fitted to S13-M transformers of 800 kVA and above? Transformers of 800 kVA and above are equipped with signal thermometers and gas relays, providing temperature tripping/alarm and light or heavy gas alarm.

Q6. What connection symbols are available? For units up to 500 kVA, Dyn11, Yzn11 or Yyn0 are available. The 630 kVA rating is typically Dyn11. For 800 kVA and above, both Dyn11 and Yyn0 are available.

Q7. Can the S13-M be installed outdoors? Yes. The S13-M is suitable for both indoor and outdoor installation, with an operating temperature range of −25°C to +40°C and altitude up to 1000 m.

Q8. What standards does the S13-M comply with? The S13-M complies with IEC 60076-1, IEC 60076-3, IEC 60076-5, IEEE C57.12.00, IEEE C57.12.90 and ANSI C57.12.10.

Need an S13-M fully sealed oil-immersed distribution transformer for your project? Contact JiangSu Dingxin Electric Co., Ltd. for datasheets, type-test reports, OEM/ODM service and competitive pricing.