110kV SZ11 Series Three-Phase Oil-Immersed Power Transformer with On-Load Tap-Changer

I. Product Overview and Model Definition

The 110kV SZ11 series three-phase oil-immersed power transformer with on-load tap-changer is an upgraded model of the S11 low-loss series. Its key advantage is on-load voltage regulation, which allows continuous voltage adjustment without power interruption, making it ideal for grids with frequent voltage fluctuations. It is a core equipment in 110kV power systems featuring high energy efficiency and stable voltage output.

This product complies with:

GB 1094.1-2013, GB/T 6451-2015, GB 20052-2020 and IEC 60076 international standards, reaching China’s Class 2 energy efficiency level or higher.

It is widely used in 110kV key substations, regional power supply centers, large industrial parks, urban distribution networks, and new energy integration projects.

Model Explanation

• S: Three-phase oil-immersed power transformer

• Z: On-load tap-changer

• 11: Low-loss series (no-load loss ≥30% lower than S9)

• 110kV: Rated high voltage

Example: SZ11-10000/110

10000 = rated capacity 10000 kVA

110 = rated high voltage 110 kV

II. Core Technical Parameters

1. Basic Parameters（customizable）

• Rated capacity: 6300–63000 kVA

• HV voltage: 110/115/121 kV

  Tap range: ±8×1.25% or ±10×1%

• LV voltage: 10.5 / 6.3 / 6.6 / 21 kV (customizable)

• Connection group: YNd11 (standard), YNyn0 (optional)

• Frequency: 50 Hz (60 Hz export type available)

• Short-circuit impedance: 10.5%–14% according to capacity

2. Loss and Efficiency

• No-load loss: ≥30% lower than S9 series

• Load loss at 75℃: meets GB/T 6451

• No-load current: ≤0.5%–0.6%

• Energy efficiency: Class 2 or above (Class 1 customizable)

3. On-Load Tap-Changer Parameters

• Voltage regulation under full load, no power interruption

• Tap range: ±8×1.25% (17 steps) or ±10×1% (21 steps)

• Switching time: ≤ 5 seconds per step

• Mechanical life: ≥ 300,000 operations

• Electrical life: ≥ 100,000 operations

• Manual / automatic / remote control supported

4. Other Key Parameters

• Insulation class: HV 450kV lightning impulse; LV 75kV

• Cooling: ONAN / ONAF / OFAF

• Noise level: 60–68 dB(A)

• Partial discharge: ≤ 100 pC

• Ambient temperature: -30℃ ~ +45℃

• Altitude: ≤ 1000m (up to 4000m customizable)

• Design life: ≥ 30 years

• Oil: 25# environmental transformer oil

III. Structure and Features

1. Core

High-permeability grain-oriented silicon steel, 45° step-lap joint, hole-free binding, low noise and low loss.

2. Windings

Oxygen-free copper conductors, cylindrical and spiral structures, high short-circuit strength, vacuum drying and impregnation.

3. On-Load Tap-Changer

Double transition resistors, arc-free switching, silver alloy contacts, integrated sealing, automatic and remote control.

4. Tank and Sealing

Q235B steel, fully sealed capsule/diaphragm structure, leak-proof, anti-corrosion painting, maintenance-free.

5. Protection System

Buchholz relay, pressure relief valve, oil gauge, thermometer, and optional DGA online monitoring.

6. Cooling System

ONAN, ONAF, OFAF with intelligent temperature control.

IV. Main Advantages

1. On-load voltage regulation

   Stable voltage without power cut, high power quality, ideal for unstable grids.

2. High efficiency and energy saving

   No-load loss reduced by over 30%, obvious electricity cost saving, short payback period.

3. Low noise and eco-friendly

   Low operating noise, fully sealed, non-polluting oil, suitable for residential and urban areas.

4. High short-circuit withstand capability

   Strong mechanical structure, high operation reliability.

5. Fully sealed and maintenance-free

   Stable oil quality, greatly reduced maintenance cost.

6. Wide applicability

   Adaptable to extreme temperatures, high humidity, plateau, coastal and corrosive environments.

V. Applications

• 110kV power grid substations

• Large industrial enterprises (metallurgy, chemical, mining, cement)

• Urban commercial and residential power supply

• Wind and solar PV power collection stations

• Plateau, low-temperature, coastal and corrosive environments

VI. Installation, Operation and Maintenance

Covers installation conditions, commissioning checks, real-time monitoring, load management, daily and periodic maintenance, tap-changer maintenance, and long-term storage rules.

VII. Supply and After-Sales Service

• Complete supply including transformer, bushings, tap-changer, protections, manual, test report

• Full factory test before delivery

• On-site installation guidance

• 1–3 years warranty

• 24-hour emergency service

• Technical training

VIII. Summary

The 110kV SZ11 series is a high-performance, energy-saving, reliable, low-noise and maintenance-free power transformer. It combines low loss and on-load voltage regulation, making it the optimal choice for 110kV power transmission, distribution, industrial power, urban grids and new energy projects.