Distribution Transformers

S20 Series 10 kV Oil-Immersed Transformer

Product Overview

S(B)20-M Series

Product Overview
S20 Series three-phase oil-Immersed transformers as the next-generation energy-efficient power equipment, it achieves a breakthrough in energy efficiency with 30% lower no-load losses and 25% reduced load losses compared to the S13 series. Featuring a core constructed from high-permeability grain-oriented silicon steel laminations with stepped-lap joints, the design minimizes hysteresis and eddy current losses, resulting in a 40% reduction in no-load current.
The fully sealed corrugated tank design automatically compensates for oil volume fluctuations caused by temperature changes through elastic deformation of the corrugated sheets. This hermetic structure eliminates the need for an oil conservator, enabling maintenance-free operation and extending service life to over 35 years.

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Model Definition

Features

● Voltage level: 10～35/0.4kV.

● Capacity: 30～3150kVA.

● High-Efficiency Energy Optimization: Leveraging next-generation energy-saving technologies, this design significantly reduces no-load and load losses compared to traditional models, meeting industry-leading efficiency standards. It substantially cuts long-term operational energy costs, making it ideal for high-load power applications with strict energy consumption control requirements.

● Low-Magnetic Loss Core Technology: Utilizes high-permeability grain-oriented silicon steel laminations with stepped-lap joint technology to minimize hysteresis loss and no-load current, reducing core heating and excitation energy loss.

● Fully Sealed Maintenance-Free Design: The corrugated tank automatically compensates for oil volume fluctuations through elastic deformation, isolating oil from air contact. This eliminates the need for an oil conservator or regular oil changes.

● Low-Noise Eco-Friendly Operation: Incorporates noise-dampening lamination technology and low-noise fans, ensuring minimal no-load and load noise levels that comply with requirements for noise-sensitive areas like urban residential zones and hospitals.

● Compact Space-Saving Structure: Features a minimized cabinet volume and footprint, suitable for space-constrained environments such as high-rise building switchrooms and subway traction substations.

● Full-Process Sealing Assurance: The tank undergoes leak testing to ensure zero leakage risk throughout the product’s lifecycle.

Range of application

Widely applicable to high-rise buildings, commercial centers, subways, airports, railway stations, industrial and mining enterprises, drilling platforms, and oil production platforms. Specifically suitable for locations with strict fire-prevention requirements (such as flammable/explosive zones) and harsh environments. Also ideal for power supply and lighting in residential areas, commercial streets, industrial sites, and rural communities.

Technical specifications

Rated capacity (kVA)	Rated voltage			Vector group	No-load loss (W)				Load loss (W)			No-load current (%)				Impedance voltage (%)
Rated capacity (kVA)	HV (kV)	Tapping range (%)	LV (kV)	Vector group	11#	13#	20#	22#	11/13#	20#	22#	11#	13#	20#	22#	Impedance voltage (%)
30	6 6.3 6.6 10 10.5 11	±5 or ±2×2.5	0.4	Dyn11 or Yyn0	100	80	70	65	630/600	505/480	455/430	0.3	0.3	0.24	0.23	4
50					130	100	90	80	910/870	730/695	655/625	0.24	0.23	0.24	0.23
80					180	130	115	105	1310/1250	1050/1000	945/900	0.22	0.18	0.21	0.20
100					200	150	135	120	1580/1500	1265/1200	1140/1080	0.21	0.16	0.21	0.20
125					240	170	150	135	1890/1800	1510/1440	1360/1295	0.2	0.15	0.19	0.18
160					280	200	180	160	2310/2200	1850/1760	1665/1585	0.19	0.14	0.18	0.17
200					340	240	215	190	2730/2600	2185/2080	1970/1870	0.18	0.12	017	0.16
250					400	290	260	230	3200/3050	2560/2440	2300/2195	0.16	0.12	0.14	0.13
315					480	340	305	270	3830/3650	3065/2920	2760/2630	0.16	0.11	0.13	0.12
400					570	410	370	330	4520/4300	3615/3440	3250/3095	0.16	0.11	0.13	0.12
500					680	480	430	385	5410/5150	4330/4120	3900/3710	0.16	0.1	0.12	0.11
630					810	570	510	460	6200	4960	4460	0.15	0.09	0.12	0.11	4.5
800					980	700	630	560	7500	6000	5400	0.15	0.09	0.1	0.1
1000					1150	830	745	665	10300	8240	7415	0.14	0.09	0.1	0.09
1250					1360	970	870	780	12000	9600	8640	0.13	0.08	0.1	0.09
1600					1640	1170	1050	940	14500	11600	10440	0.12	0.07	0.09	0.08
2000					1940	1360	1225	1085	18300	14640	13180	0.11	0.09	0.09	0.08	5.5
2500					2290	1600	1440	1280	21200	14840	13360	0.11	0.08	0.09	0.08	5.5
3150					2750	2180			24100			0.11	0.08			6

Note:

1. The load loss with two values in the table, the value on the left is applicable to the Dyn11 vector group, and the value on the right is applicable to the Yyn0 vector group.

2. The above data is subject to change due to technical improvement.

Oil-Immersed Transformer Components

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.

Oil-Immersed Transformer Applications

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.