I. Product Overview

The 220kV oil‑immersed transformer is a high‑voltage large‑capacity oil‑immersed power transformer (maximum system voltage Um = 252kV). It is researched and manufactured in compliance with domestic and international standards including GB 1094, GB/T 6451 and IEC 60076. Transformer oil is adopted for insulation and heat dissipation. It serves as the core power transformation equipment for domestic 220kV regional transmission grids and power plant step‑up stations. The products mainly include two‑winding transformers, three‑winding transformers and three‑winding autotransformers, widely used for electric energy step‑up, step‑down and power allocation between different voltage levels.

II. Basic Structural Composition

Active Part
Core made of high‑magnetism cold‑rolled grain‑oriented silicon steel sheets with full‑mitred joints; oxygen‑free copper transposed‑conductor windings optimized by electric‑field and short‑circuit force simulation. Formed insulation parts and lead compression & fastening structure ensure anti‑seismic performance for overall transportation.

Tank and Cooling System
Sealed steel‑plate welded tank. Cooling modes include ONAF, OFAF and ODAF, with OFAF being the most common for large‑capacity units.

Insulating Medium
Mineral insulating oil (custom‑made environment‑friendly synthetic ester oil available) provides insulation, heat dissipation and arc extinction.

Auxiliary Fittings
High‑voltage and low‑voltage bushings, on‑load / off‑circuit tap‑changers, oil conservator, gas relay, pressure relief valve, oil level indicator, winding / oil temperature measuring devices, cooling fans, oil chromatography on‑line monitoring, partial discharge on‑line monitoring components, etc.

III. Core Product Features

Low Loss, Energy‑Saving and Environment‑Friendly: Integrated optimized design of core, windings and magnetic shield reduces no‑load loss and load loss, complies with national energy‑efficiency standards and cuts long‑term operating energy consumption.

Reliable Insulation and Low Partial Discharge Level: Adopts vacuum drying and vacuum oil‑filling processes, optimizes internal electric‑field distribution and strictly controls partial discharge value, suitable for long‑term continuous operation.

Excellent Short‑Circuit Resistance: Windings adopt transposed conductors with reinforced end‑part insulation and supports. Verified by short‑circuit mechanical check, it can resist sudden short‑circuit impacts from the power grid.

Controllable Temperature Rise with Short‑Time Overload Capacity: Optimized oil circuit layout restrains risk of oil flow electrification. Winding temperature rise meets national standard limits and can withstand specified short‑time overload.

Low Noise and Anti‑Leakage: Vibration‑damping core and sound‑insulated noise‑reduction tank structure; fully‑sealed structure reduces moisture absorption and leakage of insulating oil, lowering maintenance frequency.

Intelligent Monitoring Expansion: Supports installation of on‑line monitoring devices for oil chromatography, micro‑water, partial discharge and vibration. It can connect to smart substation monitoring platform to realize condition‑based maintenance.

IV. Typical Application Scenarios

• 220kV urban hub substations and regional load‑center substations

• Main step‑up transformers for generators of thermal power, hydropower and large‑scale photovoltaic / wind power collection stations

• Self‑owned substations of large‑scale metallurgical, chemical, coal and other industrial and mining enterprises

• New‑construction, capacity‑expansion and renovation projects of provincial‑crossing and inter‑regional 220kV main power grids

V. Explanation of Common Model Designations (Examples)

• SFP‑180000/220: Three‑phase, forced‑air‑cooled, two‑winding power transformer with 180 MVA capacity at 220kV high‑voltage level

• SSP‑240000/220: Three‑phase, forced‑air‑cooled, three‑winding transformer

• ODFPS‑150000/220: Single‑phase, oil‑directed forced‑air‑cooled autotransformer (large‑capacity units can be combined in single‑phase form)

Common Connection Groups: YNd11, YNad11 (for autotransformer)
Voltage Regulation Modes: Off‑circuit tap changing and on‑load tap changing