Home Industry Insights Dry Type Transformer Complete Manufacturing Process: Step-by-Step Factory Production Guide

Dry Type Transformer Complete Manufacturing Process: Step-by-Step Factory Production Guide

This article walks through every step of cast resin dry type transformer manufacturing, from silicon steel coil feeding, core lamination, winding vacuum casting, full assembly to multi-stage factory performance tests. Real workshop photos show our standardized production system and strict quality control standards for 30kVA–20000kVA dry transformers.

Dry type cast resin transformers have become the mainstream power distribution equipment for hospitals, subways, data centers, commercial complexes and new energy projects due to fire resistance, low noise and zero oil leakage advantages. As a professional Chinese manufacturer featured on our Products page supplying 30kVA to 20000kVA SCB18 series dry transformers up to 35kV voltage level, Zhongxin General shares our full standardized production workflow with real on-site factory photos, covering silicon steel core processing, epoxy winding casting, overall assembly and multi-layer quality testing.

1. Silicon Steel Raw Material Processing (Core Manufacturing Stage)

The iron core determines transformer loss, noise and energy efficiency, so our silicon steel processing workshop implements full traceability quality control from raw feeding to finished core storage.

Step 1: Silicon Steel Coil Feeding

Our workshop uses overhead travelling cranes to hoist large silicon steel coils and transport raw materials onto automatic uncoiling equipment, realizing automated raw material feeding without heavy manual handling.

Worker uses overhead crane to lift silicon steel coil to uncoiling machine — *Raw silicon steel coil loading for transformer core production*

Step 2: CNC Automatic Silicon Steel Cutting

Professional operators calibrate numerical control cutting machines to realize precise automatic shearing of silicon steel sheets, ensuring consistent sheet sizes for subsequent core lamination.

Operator debugs CNC automatic silicon steel cutting equipment — *Automatic cutting machine for transformer silicon steel raw material*

Step 3: Dimensional Sampling Inspection

After cutting, quality inspectors use precision measuring tools to randomly test silicon steel dimensions and strictly control machining tolerances within national and IEC standards, consistent with the strict QC standards we apply to all cast resin dry transformers.

Worker uses measuring tool to inspect silicon steel sheet dimension tolerance — *Manual sampling inspection to control machining tolerance*

Step 4: Inspection Data Filing

All measured dimensional data of silicon steel sheets are recorded and stored electronically. Every batch of raw materials has complete quality records to achieve full lifecycle traceability for every finished transformer, which you can verify in our on-site project records from Case Studies archive.

Inspector records silicon steel dimension data for traceability — *Test data recorded for full quality traceability*

Step 5: Qualified Silicon Stacking

Silicon steel sheets passing inspection are sorted and stacked neatly according to different size specifications to avoid mixed specifications during lamination.

Qualified silicon steel sheets stacked neatly by specification — *Sorted qualified silicon steel semi-finished products*

Step 6: Partitioned Raw Material Storage

Our workshop sets independent storage zones for each silicon steel specification with clear identification labels, improving picking efficiency and preventing raw material mixing errors.

Different specification silicon steel stored in marked partition zones — *Classified silicon steel storage ar ea with clear identification labels*

1.1 Transformer Core Assembly & Insulation Treatment

Step 7: Layered Core Lamination

Technicians stack silicon steel sheets layer by layer following strict technical parameters to build the integral transformer iron core body, minimizing magnetic leakage and no-load loss — a core advantage of our high-efficiency SCB18 dry transformers compared with traditional products.、

Workers laminate silicon steel to assemble transformer core body — *Layered lamination process for dry transformer iron core*

Step 8: Steel Frame Compression Fix

After lamination, install the outer steel frame and fully tighten all bolts to compress the whole core tightly, eliminating gaps between silicon layers.

Steel frame installed and bolts tightened to compress transformer core — *Iron core compression and fixing with steel support frame*

Step 9: Core Insulation Coating

Special insulating anti-rust paint is evenly brushed over the entire core surface to enhance insulation performance and prevent moisture corrosion. This insulation process is identical to the standard we adopt for the dry transformers delivered to the Xinjin Hospital power project.

Brushing insulating protective coating on transformer core surface — *Insulation paint applied to iron core for corrosion protection*

Step 10: Insulating Tape Secondary Binding

Wrap the whole core with high-strength insulating binding tapes for secondary shaping and fixation, stabilizing the core structure under long-term operation.

Transformer core wrapped with insulating tape for secondary fixation — *Iron core secondary shaping with insulation bandage*

2. High & Low Voltage Winding Production (Core Link of Dry Transformer)

Cast resin winding is the core component distinguishing dry transformers from oil immersed transformers. Our vacuum casting process complies with EU Tier 2 energy efficiency standards specified in EU Regulation No. 548/2014.

Step 11: Thin Foil Winding Machine Operation

Before coil formal production, operators operate professional foil winding machines to wind coils evenly, maintaining consistent wire tension and neat wire arrangement for standardized winding work.

Operator operates professional foil winding machine to produce transformer coils with even wire tension — *Foil winding machine in operation for transformer coil manufacturing*

Step 12: Copper Busbar Docking Assembly

Workers precisely connect winding coils with copper busbars, ensuring low contact resistance and stable current transmission during operation. The matching HV/LV busbars and switch cabinets can be viewed on our HV/MV/LV Switchgear product page.

Worker connects winding coil with copper busbar accurately — *Precise assembly of coil and copper component*

Step 13: Precision Coil Winding

Specialized winding equipment completes fine winding for high voltage and low voltage coils separately, strictly following design turns and wire diameters.

Precise winding processing on special transformer coil machine — *High-precision winding for high & low voltage coils*

Step 14: Winding Lead Sorting & Mold Fix

Coil outgoing leads are tidily arranged and fixed with dedicated casting molds to avoid displacement during high-temperature baking and resin pouring.

Winding leads sorted and fixed with tooling mold — *Organize coil leads and install fixed tooling molds*

Step 15: Oven Dehumidification Treatment

Molded windings are sent into constant temperature industrial ovens for long-time high-temperature dehumidification to eliminate internal moisture before vacuum casting.

Molded winding placed in oven for high temperature dehumidification — *Coil dehumidification before resin casting*

Step 16: Vacuum Epoxy Resin Casting & Curing

The core vacuum casting equipment injects insulating epoxy resin under negative pressure, then the whole mold enters high-temperature baking rooms for full resin solidification. Vacuum design eliminates internal bubbles to guarantee insulation safety, which is the core craft we used for the Europe export dry transformer order recorded in our European project case.

Vacuum casting machine inject resin then high temp curing — *Vacuum pouring and high temperature solidification of winding*

Step 17: Cured Winding Demolding

After complete resin curing, workers demold the integral high/low voltage winding components without damaging cast resin surfaces.

Demold fully solidified epoxy winding component — *Take out solidified winding from casting mold*

Step 18: Winding Surface Polishing & Trimming

Manual polishing removes burrs, uneven edges and surface defects on cast winding surfaces for a smooth finish.

Worker polishes and trims high-low voltage winding surface — *Manual fine trimming of cast coil surface*

Step 19: Qualified Winding Semi-Finished Goods

Fully trimmed and inspected windings become standard semi-finished parts waiting for overall transformer assembly.

Polished finished high & low voltage winding semi-products — *Inspected cast resin winding components ready for assembly*

3. Overall Transformer Assembly Process

All semi-finished cores and windings enter the general assembly workshop for systematic assembly. Many of our complete transformer solutions are integrated into prefabricated modular substations for mining, port and LNG energy projects.

Step 20: High & Low Winding Position Calibration

Workers align high voltage and low windings accurately according to design gaps before embedding into the iron core.

Precise alignment assembly of high and low voltage windings — *Accurate calibration for winding overall assembly*

Step 21: Embed Windings into Iron Core

Disassemble the top steel core frame, then place matched high-low voltage windings into the core inner cavity accurately. This assembly flow was fully applied to the 2 sets of SCB18 transformers shipped to CATL supply chain project in Zigong.

Worker disassembles top core to install windings inside iron core — *Fit high/low coils into transformer core interior*

Step 22: Reset & Fasten Top Core

Reinstall the disassembled top core and lock all bolts to form a complete transformer main body.

Reinstall and fasten top iron core after winding fitting — *Restore and lock transformer upper core component*

Step 23: High Pressure Internal Dust Cleaning

High-pressure air blowers clear all metal dust and debris inside the assembled transformer to avoid partial discharge risks.

High pressure air blower cleans internal transformer dust — *Dust removal for assembled transformer interior*

Step 24: Cooling Fan Installation

Mount matched heat dissipation fans at the transformer bottom to control operating temperature under full load.

Install cooling fans at dry transformer bottom — *Heat dissipation fan assembly procedure*

Step 25: Top Core Insulation Paint

Repaint the exposed top core with insulating coating for secondary moisture-proof and insulation protection.

Insulation protective paint brushed on top transformer core — *Anti-insulation paint for upper iron core*

Step 26: Full Manual Visual Inspection

Experienced technicians conduct a full surface and assembly inspection, trimming small assembly flaws to improve appearance and safety.

Staff full visual inspection of complete transformer unit — *Comprehensive manual check for assembly defects*

4. Multi-Stage Factory Performance Testing (Strict Quality Control)

All finished units pass strict electrical tests before delivery. For energy storage scenarios, we also match energy storage substation dedicated dry transformers with customized testing standards.

Step 27: Preliminary Electrical Performance Test

Professional portable instruments run initial tests on loss, impedance and insulation resistance.

Professional instrument initial performance test for finished transformer — Electrical parameter test before factory delivery

Step 28: Comprehensive Final Inspection

Large professional transformer test benches carry out full-range final detection, including no-load loss, load loss, partial discharge, insulation voltage, temperature rise and other IEC standard items. All test records are archived same as our large-capacity 35kV power transformer projects.

Large test equipment full comprehensive final inspection — *Complete electrical & safety final verification*

5. Finished Dry Transformer Storage & Delivery

Step 29: Qualified Finished Product Storage

All transformers passing full final inspection are centrally stacked in our finished goods warehouse, waiting for packaging and delivery to domestic and overseas projects. Browse all completed engineering projects in our Case Studies page to view more real delivery photos.

Batch of qualified finished dry transformers stacked neatly — *All-process completed certified dry transformers warehouse storage*

Why Choose Zhongxin General Dry Type Transformers?

Our dry transformer R&D and production team is led by Chief Engineer Mr. Li Xianming with 45 years transformer industry experience, specializing in cast resin dry transformers for nearly 30 years.We have introduced German iron core manufacturing technology and upgraded the SCB18 series products to comply with Tier 2 energy efficiency requirements stipulated in EU Regulation No. 548/2014.

We supply a full set of power distribution equipment covering:

Browse our factory overview and team profile for full details of our production capacity. All technical data of our products can be checked on our product catalog page.

If you need customized dry type transformers with specific kVA, voltage or impedance parameters, visit our Contact Us page to send your requirements and get technical drawings & factory quotations promptly.

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