250kVA 10kv 400V Three Phase Oil Immersed Distribution Transformer Ynyn0 Onan

You are here: Home » Products » Distribution Transformer » 250kVA 10kv 400V Three Phase Oil Immersed Distribution Transformer Ynyn0 Onan

250kVA 10kv 400V Three Phase Oil Immersed Distribution Transformer Ynyn0 Onan

YAWEI manufactures reliable **250kVA three-phase oil immersed distribution transformers** for medium-voltage power distribution systems. Designed for a **10kV primary voltage and 400V secondary voltage**, this transformer provides stable and efficient voltage conversion for a wide range of electrical distribution applications.

With extensive transformer manufacturing experience, YAWEI supplies distribution transformer solutions to customers in international markets. The transformer adopts an **ONAN (Oil Natural Air Natural) cooling system**, using insulating oil for electrical insulation and natural circulation for heat dissipation. Its **YNyn0 connection group** is suitable for distribution networks requiring a neutral point on both the high-voltage and low-voltage sides.

The 250kVA transformer is suitable for residential, commercial, agricultural, industrial, and utility distribution systems where dependable medium-voltage to low-voltage power conversion is required.

Quantity:
Availability:





Inquire Add to Basket

Model:
S-250-33/0.4
Brand:
YAWEI
Code:
-

250kVA Distribution Transformer 10kv to 400v transformer Three Phase Oil Filled Transformer

PRODUCT CATEGORY

>> Product Introduction

>> Technical Parameters

>> Product Uses

>> Product Operate Guide

>> FAQ

Overview

The 250kVA 10kV/400V three-phase oil immersed distribution transformer is designed to provide dependable power conversion between medium-voltage distribution networks and low-voltage electrical systems. With a 10kV rated primary voltage, 400V secondary voltage, YNyn0 connection group, and ONAN cooling, it offers a practical solution for a variety of power distribution projects.

The oil immersed structure combines electrical insulation and heat dissipation within a compact transformer system, making the unit suitable for long-term operation under normal outdoor or indoor installation conditions, subject to the applicable project requirements.

Core Advantages & Operational Benefits

Reliable Three-Phase Power Distribution

With a rated capacity of 250kVA, the transformer is designed to supply balanced three-phase electrical loads in medium- and low-voltage distribution networks. The 10kV/400V configuration is suitable for converting utility distribution voltage into a commonly used low-voltage power supply.

Efficient ONAN Cooling System

The transformer uses ONAN cooling, in which transformer oil naturally circulates through the tank as temperature changes. Heat generated by the core and windings is transferred through the insulating oil and dissipated naturally through the tank surface, providing a simple and dependable cooling arrangement without forced cooling equipment.

Oil-Immersed Insulation Structure

The active components are immersed in insulating oil, providing effective electrical insulation while helping transfer operating heat away from the windings and core. This design has been widely adopted for distribution transformer applications because of its straightforward construction and reliable operating characteristics.

Practical 10kV/400V Configuration

The 10kV primary and 400V secondary voltage configuration makes this transformer suitable for stepping down medium-voltage utility power for use by low-voltage electrical equipment. It can serve a broad range of conventional distribution applications.

Designed for Long-Term Operation

YAWEI combines carefully selected magnetic core materials, winding components, insulating materials, and a robust tank structure to support dependable transformer operation. Manufacturing and factory inspection procedures are applied throughout the production process to maintain consistent product quality.

>> Technical Parameters

Type	Three‑phase oil‑immersed distribution transformer
Model	S20-M-250kVA
Installation	Outdoor
Altitude	≤1000m
Rated Power	250 kVA KVA or others
Cooling Method	ONAN
Primary Voltage	10 kV
Secondary Voltage	0.4 kV
Rated Frequence	50/60HZ
Insulation oil	Mineral oil
Tapping Range	±2×2.5%/±5%
Temperature rise℃)	65 K
Connection Group
Total weight(kg)	Depends on final design

Industry Applications

The 250kVA 10kV/400V oil immersed distribution transformer can be used in a wide range of power distribution environments. Typical applications include residential communities, commercial buildings, factories, agricultural facilities, rural electrification projects, infrastructure facilities, and utility distribution networks.

It can supply power to lighting systems, motors, building electrical equipment, agricultural machinery, small industrial loads, and other low-voltage consumers. Its three-phase configuration makes it particularly suitable for distribution systems serving multiple types of electrical loads.

Quality Standards, Testing & Manufacturing Control

YAWEI follows controlled manufacturing and inspection procedures throughout the production of its three-phase oil immersed distribution transformers. Before shipment, each transformer undergoes applicable routine factory testing to verify its electrical and mechanical performance.

Depending on the project specification and applicable standards, testing may include voltage ratio, winding resistance, insulation performance, dielectric withstand, no-load characteristics, load-related performance, and other required inspections.

Quality management is implemented from incoming material inspection through core assembly, winding, insulation, tank manufacturing, oil processing, final assembly, and factory testing. This systematic approach helps ensure reliable performance and consistent product quality.

Why Choose YAWEI

With more than 30 years of experience in transformer manufacturing, YAWEI has developed extensive expertise in the production of distribution and power transformers for international customers.

Our engineering and production teams combine practical transformer design experience with controlled manufacturing processes and systematic testing. We can also provide customized solutions according to project requirements, including rated capacity, voltage ratio, frequency, connection group, impedance, tap range, cooling method, installation conditions, and applicable standards.

YAWEI is committed to providing reliable transformer products and professional technical support for residential, commercial, industrial, agricultural, and utility power distribution projects.

Generic Installation and Operation Instructions

The following instructions provide general guidance for installing and commissioning the 250kVA 10kV/400V oil immersed distribution transformer. Actual installation and commissioning must be performed by qualified electrical personnel in accordance with the manufacturer's technical documents, approved engineering drawings, local regulations, and applicable electrical safety standards.

1. Preparing the Installation Site

Before installation, inspect the designated location and confirm that the foundation or supporting structure is level, stable, and capable of carrying the transformer load. Provide sufficient working clearance, grounding facilities, ventilation, and safe access for installation, inspection, and maintenance.

2. Positioning and Securing the Transformer

Use suitable lifting equipment and approved lifting points to move the transformer into its designated position. Ensure that the transformer is correctly aligned and securely fixed before proceeding with electrical connections. Do not lift or move the transformer using components that are not designed for lifting.

3. Installing Transformer Components

Inspect the transformer, bushings, terminals, accessories, and other components for possible transportation damage. Install and secure the required accessories according to the manufacturer's drawings and technical instructions. Check all mechanical connections before energization.

4. Connecting the High- and Low-Voltage Wiring

Connect the 10kV high-voltage side and 400V low-voltage side according to the transformer nameplate, wiring diagram, and approved electrical design. Verify terminal identification, phase sequence, neutral connection, grounding, conductor clearances, and connection tightness before applying voltage.

5. Pre-Commissioning Inspection and Testing

Before energization, qualified personnel should complete the required visual, mechanical, and electrical inspections. Depending on the applicable specification, tests may include insulation resistance, winding resistance, voltage ratio, polarity or phase relationship, dielectric withstand, grounding continuity, and other routine tests.

The transformer should only be energized after all inspection and test results meet the specified requirements and the installation has been confirmed safe and complete.

>> FAQ

1. What are the main specifications of this 250kVA distribution transformer?

The transformer has a rated capacity of 250kVA, a 10kV primary voltage, and a 400V secondary voltage. It uses a three-phase YNyn0 connection group and an ONAN cooling system.
2. What is the meaning of YNyn0?

YNyn0 indicates the transformer winding connection configuration. The high-voltage and low-voltage windings both have neutral points, while the phase displacement between the two sides is 0°. This configuration can be selected for distribution systems where neutral points are required on both voltage levels.
3. What does ONAN mean in an oil immersed transformer?

ONAN stands for Oil Natural Air Natural. Transformer oil circulates naturally inside the tank and transfers heat from the core and windings to the tank surface, where the heat is dissipated naturally into the surrounding air.
4. Where can a 250kVA 10kV/400V transformer be used?

This transformer can be used for residential, commercial, agricultural, industrial, and utility distribution applications. Typical loads include building electrical systems, lighting, motors, agricultural equipment, and other low-voltage power consumers.
5. Can YAWEI customize the 250kVA transformer for a specific project?

Yes. YAWEI can customize transformer specifications according to project requirements, including voltage ratio, frequency, connection group, impedance, tap range, cooling method, enclosure configuration, installation conditions, and applicable international or local standards. Customers can provide their technical specifications for engineering review.