110kV SS11 Series Three-Phase Three-Winding Oil-Immersed Power Transformer

1. Product Overview

The 110kV SS11 series three-phase three-winding oil-immersed power transformer is an energy-saving transmission and transformation equipment developed on the basis of S11 low-loss technology with a three-winding structure.

It is used for power conversion and distribution at multiple voltage levels: 110kV high voltage, 35kV/10kV medium voltage, and 10kV/6kV low voltage.

Meaning of SS11:

• First S: Three-phase

• Second S: Three-winding

• 11: Low-loss performance level (no-load loss reduced by ≥30% compared with S9)

• 110kV: Rated high voltage class

This product complies with national standards GB 1094, GB/T 6451, GB 20052-2020 and international standard IEC 60076.

It is widely used in 110kV substations, regional power supply centers, large industrial parks, metallurgy, chemical industry, new energy collection stations and other multi-voltage power supply scenarios.

2. Model Definition & Structural Features(Customizable)

2.1 Model Definition

SS11–Capacity/110

• S: Three-phase oil-immersed

• S: Three-winding structure

• 11: Low-loss level

• 110: High voltage rated 110kV

2.2 Structural Features

• Three-winding structure: HV + MV + LV, capable of outputting 110kV, 35kV, 10kV simultaneously

• Three-limb or five-limb core with uniform magnetic circuit

• Three-winding capacity can be allocated as 100%/100%/100% or 100%/50%/50%

• Fully sealed oil-immersed structure, with corrugated tank or capsule sealing

• Suitable for complex power supply systems with multi-power, multi-load and multi-voltage levels

3. Core Technical Parameters

3.1 Rated Capacity

• HV winding: 6300～63000kVA

• MV winding (35kV/10kV): Equal to HV or proportionally allocated

• LV winding (10kV/6kV): Equal to HV or proportionally allocated

3.2 Rated Voltage

• HV: 110kV / 115kV / 121kV (±2×2.5% off‑load tap changing)

• MV: 35kV or 10kV

• LV: 10kV or 6kV

3.3 Connection Group

• Standard: YNyn0d11

• Optional: YNd11, YNyn0, YNynd11

3.4 Short-Circuit Impedance (Typical)

• HV–MV: 10.5%～14%

• MV–LV: 6.5%～8%

• HV–LV: 10.5%～14%

3.5 Loss Characteristics

• No-load loss: ≥30% lower than S9, meets Class 2 energy efficiency

• Load loss: Complies with GB/T 6451

• No-load current: ≤0.5%

3.6 Insulation Level

• Lightning impulse: 450kV (peak)

• Power-frequency withstand voltage: 200kV (RMS)

3.7 Cooling Mode

• ONAN (Oil Natural Air Natural)

• ONAF (Oil Natural Air Forced)

• OFAF/ODAF available for large capacity

3.8 Noise Level

• ONAN: ≤65dB(A), can be optimized to ≤60dB(A)

3.9 Ambient Conditions

• Ambient temperature: -30℃～+45℃

• Altitude: ≤1000m (plateau type customizable)

• Humidity: ≤95% (at 25℃)

4. Structural & Technological Features

4.1 Core

• High-permeability grain-oriented cold-rolled silicon steel (0.27–0.30mm)

• Multi-step step-lap joint, hole-free binding

• Three-limb or five-limb structure: low magnetic resistance, low vibration, low noise

• Phosphating and painting for moisture and rust resistance

• Seamless wound core available for lower loss and noise

4.2 Three-Winding Structure

• HV: Multi-layer cylindrical type, reliable insulation, high short-circuit strength

• MV: Spiral or continuous type, good heat dissipation, uniform current distribution

• LV: Foil or spiral type, suitable for heavy current

• Oxygen-free copper conductors, low loss, high conductivity

• Vacuum drying and impregnation, low partial discharge

• End reinforcement for excellent sudden short-circuit withstand capability

4.3 Tank & Sealing

• High-quality steel welding, ultrasonic testing, zero leakage

• Corrugated tank or capsule sealing, fully sealed against oxidation

• Anti-corrosive painting

• Oil conservator / capsule for oil volume compensation

• Oil-resistant & aging-resistant gaskets

4.4 Insulation System

• Composite insulation: pressboard + transformer oil + epoxy parts

• Vacuum drying, low moisture content

• Partial discharge ≤100pC

• Insulation class A (105℃)

4.5 Protection System

• Buchholz relay (light alarm, heavy trip)

• Pressure relief valve

• Oil level gauge

• Analog / digital thermometer

• Optional: DGA online monitoring, temperature monitoring, automatic fan control

4.6 Cooling System

• ONAN: natural convection, energy-saving, low noise

• ONAF: automatic fan control, improved overload capacity

• Intelligent temperature control: over-temperature alarm, fan linkage

5. Core Advantages

1. High Efficiency & Energy Saving

• No-load loss reduced by ≥30% vs. S9

• Significantly lower annual power cost

• Ideal for long-term light-load / no-load operation

• In line with national “dual carbon” policy

• Simultaneous multi-voltage output: 110kV, 35kV, 10kV

• Suitable for multi-power, multi-load systems

• Reduces equipment quantity and investment

• Optimized core, noise ≤65dB(A)

• Fully sealed, no oil leakage, no volatile pollution

• Eco-friendly transformer oil

• High winding rigidity

• Stable core and clamping structure

• Withstands sudden short-circuit impact

• Oil isolated from air, stable oil quality

• No frequent oil replacement or filtration

• Maintenance cost reduced by over 60%

• Resistant to high/low temperature, humidity

• Customizable for plateau, anti-corrosion, coastal salt-fog

• Outdoor protection IP33

• Design life ≥30 years

• High-quality materials & strict manufacturing

• Full routine test before delivery

6. Application Scenarios

1. Power Grid

   110kV substations, regional power supply centers, urban distribution network upgrading

2. Industrial Enterprises

   Metallurgy, chemical, mining, cement, large industrial park step-down substations

3. New Energy Stations

   PV power 110kV collection stations, wind farm 110kV boosting stations

4. Urban Construction

   Commercial complexes, rail transit, airports, high-speed rail stations, residential districts

5. Special Environments

   Plateau, cold regions, coastal salt-fog, chemical corrosive environments

7. Installation, Operation & Maintenance

7.1 Installation

• Stable, level foundation with good ventilation

• Reliable earthing (earthing resistance ≤4Ω)

• Standard and firm HV/LV connections

7.2 Operation

• Monitor oil temperature, oil level, current, voltage

• Avoid long-term overload

• Keep radiators clean

7.3 Maintenance

• Routine: check oil level, oil condition, appearance

• Periodic: oil test, insulation test, partial discharge test

• Long-term outage: run fans periodically, inspect insulation