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Oil immersed transformer

Discover high-performance oil-immersed distribution transformers engineered to optimize local power grids. Designed to step down primary voltage to safe, usable levels for end-users, our oil-filled distribution transformers serve as the reliable backbone of modern power distribution networks. Available in a wide range of kVA ratings and voltage classes, they feature optimized core designs, high-quality conductors, and premium insulating oil for superior cooling — ensuring minimal energy loss, excellent voltage regulation, and robust overload capacity. Built for long service life in residential, commercial, and light industrial applications, our oil-immersed distribution transformers deliver stable, efficient power delivery, essential for modern, responsive utility networks.

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Product Selection and Customization

Advanced Manufacturing Rooted in a Complete Industrial Ecosystem

Advanced Manufacturing Rooted in a Complete Industrial Ecosystem

Our advanced manufacturing factory operates at the heart of a full-category manufacturing ecosystem, giving us access to a complete supply chain — from raw materials and precision components to electrical testing equipment. This integrated ecosystem enables end-to-end production of pad mounted transformers, with strict quality control at every stage. Equipped with modern fabrication lines and professional testing facilities, we ensure every single phase and three phase pad mounted transformer meets international standards before delivery, providing reliable power solutions for residential, commercial, and industrial applications worldwide.

Factory Customization Services

We build single-phase and three-phase pad mounted transformers to order. Standard range: 25–2,500 kVA, primary voltage 15 kV, 25 kV or 35 kV, secondary voltage 120/240 V, 208Y/120 V or 480 V, 50 or 60 Hz. Custom options include impedance, off-circuit tap range (±2 × 2.5%), winding material, tank size, enclosure type, color/coating, bushings, load-break switches, fuses, and surge arresters. Units comply with ANSI/IEEE C57.12.20, C57.12.25, C57.12.26 and C57.12.38; UL certification available on request. Send your spec sheet or application details — our engineers return a full design with drawings and test data before production.
Factory Customization Services
High Efficiency and Energy Saving

High Efficiency and Energy Saving

Low-loss design cuts operating cost. Amorphous metal cores reduce no-load loss sharply versus conventional silicon steel, and material selection keeps load loss low. Units meet DOE 2016 efficiency and are built ready for DOE 2029 levels; three-phase efficiency is typically 97.9–99.3%. Lower losses mean less wasted heat and lower electricity bills over the transformer's life, with the biggest savings in continuous or lightly loaded service.

Safety, Stability, and Low Maintenance

Dead-front, fully enclosed construction with lockable, tamper-resistant compartments prevents contact with live parts (ANSI/IEEE compliant). The hermetically sealed, corrosion-resistant tank with mineral oil or FR3 oil maintains stable dielectric and thermal performance. Every unit is factory tested: ratio, impedance, no-load and load loss, induced voltage, and dielectric. The sealed design needs no oil sampling or reconditioning — only routine visual inspection. Design life: 25–30 years.
Safety, Stability, and Low Maintenance

Installation and Application Environment

The pad-mounted transformer is a versatile, field-proven solution for outdoor power distribution. Mounted on a concrete pad, it serves a wide range of applications-from residential communities and commercial complexes to rural networks and industrial sites -delivering steady, reliable performance across diverse climates. Its factory-integrated design enables rapid deployment and immediate commissioning with minimal on-site work. Engineered for safe, durable service, it only requires the installation site and surroundings to meet the following conditions:
Temperature Range -40℃ ~ +55℃
Temperature Range
-40℃ ~ +55℃
Humidity Adaptation 0 ~ 100% RH
Humidity Adaptation
0 ~ 100% RH
Seismic Resistance Level IEC 60068-2-57
Seismic Resistance Level
IEC 60068-2-57
Altitude ≤3000m
Altitude
≤3000m

Production Process

1、Drawing/Design Engineering
1.Drawing/Design Engineering
Define equipment functions and parameters based on customer requirements​​​​​​​.
2、Raw Material Procurement & Incoming Inspection
2.Raw Material Procurement & Incoming Inspection
Silicon steel sheets, copper wire, insulation materials, steel plates​​​​​​​.
3.Core Manufacturing
3.Core Manufacturing
Silicon steel cutting, and stacking​​​​​​​.
4、Coil Winding
4.Coil Winding
Automatic winding, interlayer insulation treatment.
5、Enclosure Fabrication
5.Enclosure Fabrication
Enclosure welding and anti-rust treatment.
6、Insulation & Active Part Assembly
6.Insulation & Active Part Assembly
Insulation treatment, lead wire assembly.
7、Vacuum Drying & Varnish Impregnation
7.Vacuum Drying & Varnish Impregnation
Vacuum dehumidification, varnish impregnation and curing.
8、Final Assembly
8.Final Assembly
Enclosure and accessory installation, sealing test.
9、Factory Acceptance Inspection
9.Factory Acceptance Inspection
Full routine tests.
Testing and Certification​​​​​​​
  • EU CE Certificate of Conformity (UDEM)
  • Quality Management System Certificate (ISO 9001)
  • Test Report
  • ASTA Type Test Certificate (Intertek)
  • Environmental Management System Certificate (ISO 14001)

Order Process

Customer Needs Analysis & Parameter Confirmation
​​​​​​​Customer Needs Analysis & Parameter Confirmation
Type, kVA, voltages, impedance, cooling, standard (IEC/IEEE/ANSI), qty, destination datasheet, drawings, lead time​​​​​​​.
Order Confirmation
PI, contract, payment terms，OEM Details，brand logo, serial no., label language, local marks.
Order Confirmation

Stock Available in Warehouse?

In-Stock · Picking & Dispatch

In-Stock · Picking & Dispatch

Production & QC

Production & QC

Raw Material Inspection, Core Cutting & Stacking, Winding & Insulation, Vacuum Drying, Tank Fabrication & Assembly, Oil Filling & Treatment, Routine Tests, Type Tests , Inspection Reports, Test Certificates, FAT, QC Photos & Videos
Dispatch Preparation

Dispatch Preparation

Export Packing, Desiccant & Breather, Lifting Lugs & Skid Base, Shipping Marks, Packing List, Loading Plan & Photos, Cargo Survey, Insurance, Export Documents (Invoice, PL, CO), Customs Clearance, Booking Confirmation
Shipping

Shipping

Transport Mode (Sea/Air/Rail/Road), Container & Vessel Loading, Fumigation Certificate, Bill of Lading, Shipping Advice, ETD/ETA, Incoterms (FOB/CIF/DDP), Onboard & Lashing Photos
Transport Tracking & Feedback

Transport Tracking & Feedback

Vessel/Container Tracking, Voyage Monitoring, Port Discharge, Destination Customs Clearance, Arrival Notice, Status Updates, Delay/Issue Alerts, Customer Feedback, Claims Handling
Customer Receives Goods

Customer Receives Goods

Unloading & Visual Inspection, Checklist vs Packing List, Damage/Shortage Check, Photo Evidence, Delivery Receipt Sign-off, Storage Advice (Oil Level, Breather), Installation Readiness
Acceptance & After-Sales

Acceptance & After-Sales

 
Weilai Electric boasts a team of experienced engineers providing full-lifecycle support—ranging from transformer design consultation and technical drawings to on-site guidance and after-sales service—ensuring customer peace of mind at every stage of the project.

Specific services include: commissioning support, on-site testing (turns ratio, insulation, oil sample analysis), acceptance certification, warranty coverage, technical support, spare parts supply, maintenance guidance, handling of complaints and claims, and feedback management for long-term cooperation.
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FAQ

  • Q What is a new energy transformer?

    A "New energy" or renewable-energy transformers are specially engineered units for solar (PV) plants, wind farms, battery energy storage systems , EV charging infrastructure and distributed generation. They include:
    Step-up transformers
    ● that raise inverter output (e.g. 600 V–1,500 V DC side / low-voltage AC) to medium-voltage collection levels (e.g. 33–35 kV)
    Containerized or skid-mounted transformer stations
    ● that integrate transformer, switchgear and auxiliary systems in one transportable unit
    Green transformers
    ● using environmentally friendly insulating fluids (natural esters) and high-efficiency core designs 

  • Q What is a pad-mounted transformer?

    A A pad-mounted transformer — often called a padmount or "box-type" transformer — is a ground-mounted distribution transformer enclosed in a locked steel cabinet installed on a concrete pad. It connects underground primary cables to underground secondary cables, which is why it is the standard solution for underground residential distribution (URD) and commercial underground power systems.

  • Q What is a dry-type transformer?

    A A dry-type transformer cools its windings with ambient air instead of liquid — it is also called an air-cooled or ventilated transformer. Enclosure vents allow air to flow over the core and coils. Because air is a less effective cooling medium than oil, dry-types run at higher average winding temperatures and use solid insulation such as aramid paper or cast resin instead of fluid.

  • Q What is an oil-immersed transformer?

    A An oil-immersed transformer — also called a liquid-filled, oil-filled  transformer — uses dielectric fluid to cool, insulate and lubricate its internal components. The most common fluids are mineral oil, FR3 natural ester and silicone. Common configurations include pad-mounted, pole-mounted and substation transformers.

  • Q What is a distribution transformer?

    A A distribution transformer is the final voltage-conversion device between the utility distribution network and the end user. It steps down medium distribution voltage to the low voltage used by homes, businesses and industrial equipment (e.g. 120/240 V, 480 V, 600 V).
The Group's core businesses cover high-end manufacturing and industrial fields such as chemical products, transformers, and electrical equipment, with transformers and other electrical equipment being the Group's strategic leading industries.

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 Tel: +86-18356911563
 Add: Shunhua Road Subdistrict, Lixia District, Jinan City, Shandong Province
 Opening Hours： 
work every day 9:00–18:00
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