S20-M 1250 kVA 11 kV ONAN Distribution Transformer

1. Main Heading and Overview
The 1250 kVA oil immersed transformer is one of the most widely specified capacities in medium-voltage power distribution. SUNENG manufactures this transformer in the S20-M series, a low-loss product line engineered for continuous outdoor service in utility networks, industrial plants, mining sites, and large commercial facilities.

2. Structure and Design

Low-loss grain-oriented silicon steel core reduces no-load losses over the transformer’s service life.

4. FTypical Applications
Typical applications include step-down substations of 10 kV and 11 kV networks, industrial power distribution, renewable energy collection stations, infrastructure projects, and commercial building substations .

Reference component and partner-factory production images. Components, conservator and breather availability depend on the selected design.

Test Control Panel

Steel control panel operating routine-test circuits (ratio, insulation resistance, dielectric) for safe, standard-compliant testing.

Flange Connection

High-strength bolted flange with machined sealing face and oil-resistant gasket — a leak-free oil path for the long run, and easy to open when service is needed.

Finished Porcelain Bushings

Multi-shed porcelain bushings increase creepage distance to cope with outdoor dust and rain.

Transformer Core and Clamp Structure

Painted steel clamps and tie rods hold the laminations tight to cut noise, with single-point core earthing to prevent floating discharge.

Heat Dissipation Panel

Pressed or welded steel fins, phosphated and powder-coated, enlarge the radiating surface and release heat by natural oil convection.

Silica Gel Breather

The silica gel breather is installed at the end of the conservator breathing pipe. The color-indicating silica gel inside appears blue/purple when dry and turns pink once saturated, allowing a quick visual check for replacement. As the oil volume expands and contracts, the breather continuously filters the air entering the conservator and prevents moisture from reaching the transformer oil — a key component for maintaining insulation performance. The oil cup at the bottom allows oil-level observation and dust separation.

Oil-Immersed Transformer Production Line

Reference image from the partner factory. Standardized line covering assembly, drying, oil filling and painting ensures batch consistency and short lead times for export orders.

10 kV Distribution Transformer Testing Area

Reference image from the partner factory. Finished S11/S13/M units are tested one by one before dispatch, verifying electrical and insulation performance with test reports supplied.

Typical application scenarios. The installations shown are examples; voltage, capacity and mounting arrangement require project-specific confirmation.

Pole-Mounted Transformer: Rural Supply

Where used: Serves scattered rural loads such as village supply and irrigation wells — pole-mounted for minimal land use, fast installation and low cost.

Outdoor Substation: Regional Grid

Where used: Main-transformer bays of 35–110 kV substations, stepping down and distributing power to cities, towns and industrial load centers.

Solar Power Station: Grid Connection

Where used: Steps up PV inverter output to 10/35 kV for grid connection, coping with strong UV, wide temperature swings and day-full / night-light duty.

Industrial Park: Factory Supply

Where used: Supplies industrial parks, plants and mine processing facilities — production lines, large motors and compressors — with dust-resistant, continuous heavy-load capability.