Shinenergy Dry Type Transformers Manufacturing Process

Dry type transformers are widely used in applications that demand safety, environmental protection, and low maintenance, such as commercial buildings, data centers, and renewable energy systems. Unlike oil-immersed types, they require no liquid insulation and offer reduced fire risk. But performance doesn’t just come from design. It’s the Transformer Manufacturing Process—how the core is stacked, how the coils are wound, how the insulation is applied—that determines whether a transformer performs reliably for 20 years or fails prematurely.

At Shinenergy, we believe that manufacturing quality defines transformer quality. In the sections below, we walk through each step of our dry type transformer production process, from materials to testing, to show how reliability is built from the inside out.

Dry Type Transformer

Transformer Manufacturing Process Overview

The Dry Type Transformer Manufacturing Process involves a series of precise and controlled steps—from raw material preparation to final testing and packaging. Each stage plays a critical role in shaping the transformer’s electrical performance, thermal behavior, and mechanical durability.

Here is a simplified view of Shinenergy’s dry type transformer production process:

Dry Type Transformer Manufacturing Process

Step-by-Step Dry Type Transformers Manufacturing Process

Transformer Core Stacking – Precision Assembly of the Magnetic Circuit

The transformer core is the magnetic heart of any dry type transformer. At Shinenergy, we utilize a stacked core transformer design, assembled with precision to ensure minimal no-load loss, low vibration, and optimal performance.

Our Dry Type Transformer Manufacturing Process begins with high-grade CRGO (cold-rolled grain-oriented) silicon steel laminations, which are CNC-cut into precise dimensions. These laminations are then stacked layer by layer on a dedicated transformer core stacking table, forming a step-lap joint configuration that reduces magnetic flux leakage and minimizes noise.

For mid- to large-capacity units, we use a semi-automated transformer core stacking machine to ensure consistent alignment, stacking height accuracy, and reduced manual variation. This equipment supports the precise layering and positioning of laminations while controlling both the core geometry and air gap distribution. In OEM projects, Shinenergy also provides customized production support with our OEM transformer core stacking machine platform.

To ensure high assembly quality, Shinenergy implements three critical controls during the core stacking process:

• Thickness consistency control to maintain magnetic uniformity;
• Flatness control to eliminate local deformation and gaps;
• Torque control during core clamping to ensure mechanical stability without inducing stress.

Once stacking is complete, the entire core assembly is clamped, dried, and coated with rust-preventive oil to enhance durability, especially in humid or coastal environments.

By investing in modern stacking technology and rigorous process control, Shinenergy ensures every transformer core stacking operation supports long-term reliability, electrical efficiency, and quiet operation, laying a solid magnetic foundation for each dry type transformer.

Dry Type Transformers Coil Winding – Custom Coil Winding for Optimal Electrical and Thermal Performance

The coil winding process is one of the most critical stages in Transformer Manufacturing Process. At Shinenergy, we apply advanced coil winding technology to ensure each transformer meets the highest standards of electrical integrity, thermal stability, and mechanical durability.

Conductor Materials & Insulation

Our windings are made from high-purity copper or aluminum conductors, selected based on customer specifications and operating environments. We apply Class F or H insulation systems, using heat-resistant polyester films, mica tape, and epoxy-coated fiberglass to ensure long-term dielectric strength.

Winding Structure & Method

• Low Voltage (LV) windings are typically constructed using foil winding machines, forming flat, wide coils with strong short-circuit withstand capacity and improved heat dissipation.

• High Voltage (HV) windings are executed using multi-layer helical or barrel winding techniques, allowing precise voltage control and enhanced axial mechanical strength.

Advanced Coil Winding Machines

All coils are wound using CNC-controlled coil winding machines. These high-precision systems ensure:

• Accurate turn count and conductor spacing;
• Consistent winding tension to avoid insulation damage;
• Automated placement of layer-to-layer insulation and cooling channels.

For large or customized transformers, we deploy transformer coil winding machines capable of handling variable conductor sizes, customized pitch control, and programmable interlayer insulation patterns. This enables Shinenergy to provide fully custom coil winding solutions for complex industrial applications.

Quality Control & Preprocessing

Every coil undergoes dimensional verification and resistance measurement before proceeding to further stages. Coils are then pre-dried at 110–130°C for 8–12 hours to eliminate residual moisture and stabilize their mechanical form. In high-power applications, air ducts or ventilation spacers are embedded between winding layers to promote convection and reduce hot spots.

By integrating modern coil winding machines, expert craftsmanship, and rigorous process control, Shinenergy ensures that every winding contributes to the transformer’s low loss, low noise, and long-life operation.

Dry Type Transformers Pre-Assembly – Structural Integration Before VPI

The transformer pre-assembly stage is a critical transition point where individual components—core, coils, structural parts, and terminals—are mechanically and electrically integrated prior to vacuum pressure impregnation (VPI). At Shinenergy, we follow a tightly controlled dry type transformer assembly process to ensure the reliability, insulation integrity, and mechanical stability of every unit we produce.

Coil to Core Assembly

Once the coils are dried and shaped, they are carefully aligned and positioned onto the iron core. This coil to core assembly must achieve precise axial centering to maintain uniform magnetic flux distribution and avoid stress concentrations. Any misalignment can lead to partial discharges, hot spots, or mechanical failure over time.

Shinenergy uses custom insulating supports for transformer coils and precision-guided positioning frames to ensure accuracy and minimize handling stress. For larger units, we employ rail-mounted lifting jigs to safely lower coils into position without damaging insulation surfaces.

Mechanical Clamping and Structural Stabilization

After mounting, the structure is fixed using a combination of:

• Pressboards, fiber-reinforced spacers, and compression rings to secure the coil radially;
• End blocks and vertical rods to counter axial forces;
• Torque-calibrated fasteners, which provide consistent, controlled pressure to avoid deformation.

This stage of mechanical clamping in transformer assembly is crucial for ensuring vibration resistance and mechanical integrity during transport and operation.

Lead Connection and Routing

At this point, transformer lead connections are temporarily routed and fixed in preparation for final termination. We pay close attention to:

• Conforming to standard creepage and clearance distances;
• Using flexible copper or tinned braids to absorb thermal expansion;
• Protecting insulation at all bends and terminations.

If the design includes thermal monitoring, we embed transformer temperature sensors such as PT100 probes or thermal relays at key hot spots inside the windings.

Pre-VPI Surface Cleaning and Inspection

Before the assembly enters the VPI chamber, all external and internal surfaces are cleaned of debris, metal particles, or grease. Our inspection checklist includes:

• Verification of alignment in the Dry Type Transformers assembly;
• Fastener torque re-check;
• Confirmation of mechanical and dielectric clearances.

Through precise pre-assembly, Shinenergy ensures that every component is mechanically secured, aligned, and ready for uniform epoxy impregnation. This process guarantees that the resin can fully penetrate the structure, forming a solid dielectric barrier and improving thermal performance for long-term dry type transformer reliability.

Dry Type Transformers Vacuum Pressure Impregnation Process for Dry Type Transformers

What is vacuum pressure impregnation? Commonly referred to as VPI (vacuum pressure impregnation), this is a critical insulation method widely used in dry type transformer manufacturing. The process enhances the dielectric strength, moisture resistance, and mechanical rigidity of the entire coil-core assembly by infusing it with vacuum pressure impregnation resin under carefully controlled conditions.

At Shinenergy, we use a fully automated vacuum pressure impregnation system integrated into our production line to ensure every vacuum pressure impregnated dry type transformer meets the highest standards of safety and reliability.

Step-by-Step VPI Process

The vacuum pressure impregnation process for transformers consists of three key phases:

Vacuum Extraction Phase
The complete coil-core assembly is placed into a sealed vacuum pressure impregnation tank, where air and moisture trapped inside the insulation and winding gaps are removed. This ensures maximum resin penetration and prevents voids that may lead to partial discharge.

Resin Impregnation Phase
A low-viscosity, thermosetting vacuum pressure impregnation resin is introduced into the chamber. The resin flows into the windings, filling micro-crevices throughout the structure.

Pressurization Phase
The chamber is then pressurized to 3–6 bar, forcing the resin deep into the coil layers. This improves bonding and mechanical integrity between the vacuum pressure impregnation winding, insulation layers, and structural components.

The entire process is managed using Shinenergy’s proprietary vacuum pressure impregnation equipment, ensuring uniformity and resin saturation across all transformer sizes and voltage ratings.

Curing in Oven

Following impregnation, the transformer is transferred to a curing oven where it is heated to 130–150°C for up to 12 hours. This polymerizes the resin, converting it into a solid insulating shell that locks in the coil’s geometry and protects against moisture, dust, and chemical agents.

 Why VPI?

Compared to cast resin technology, vacuum pressure impregnation systems offer:

• Greater flexibility in winding configurations
• Lighter and more compact final structure
• Superior thermal cycling endurance
• Easier maintenance and repair options

As a result, every vacuum pressure impregnated transformer produced by Shinenergy features:

• Low partial discharge levels (<10pC)
• Excellent moisture resistance
• High mechanical strength under dynamic loads

Summary

The VPI vacuum pressure impregnation process is more than just an insulation step—it’s a critical barrier against failure. By leveraging advanced vacuum pressure impregnation machines, proven resins, and tightly controlled parameters, Shinenergy ensures each vacuum pressure impregnated dry type transformer delivers dependable performance in demanding industrial environments.

Final Assembly – From Functional to Complete

After vacuum pressure impregnation (VPI) and curing, the dry type transformer enters its final stage of production: final assembly and finishing. This phase transforms the functional core-and-coil structure into a fully operable, protected, and transport-ready transformer unit.

At Shinenergy, we follow a standardized yet flexible final assembly process to accommodate varying application requirements and customer specifications.

Installation of Cooling and Monitoring Components

Depending on the design, natural air cooling (AN) or forced air cooling (AF) systems are applied.

Key components installed during this step include:

• Cooling channels and air ducts between windings or along outer surfaces to facilitate convection.
• Axial or radial cooling fans, mounted externally and controlled via thermal relays for intelligent temperature regulation.
• Temperature monitoring devices such as PT100 sensors, analog thermostats, or digital thermal controllers, placed near the hottest points of the coil.
• Over-temperature protection relays, connected to alarm systems or fan starters to prevent thermal overload.

These components not only improve the transformer’s thermal performance but also extend service life and reduce maintenance needs.

Protective Enclosure and Terminal Box Installation

Shinenergy transformers are equipped with protective enclosures according to the required ingress protection level (e.g., IP20, IP23, or IP54). These metal housings shield the internal components from dust, moisture, and mechanical damage, especially in outdoor or industrial settings.

We also install:

• LV and HV terminal boxes or busbar chambers for safe electrical connection;
• Grounding terminals with proper clearance;
• Optional anti-condensation heaters for high-humidity or coastal applications.

Finishing Touches: Labeling, Painting, and Packing

To ensure both aesthetics and traceability, every transformer undergoes the following finishing steps:

• Final surface cleaning and anti-corrosion treatment, including primer coating and paint finish with Shinenergy’s standard grey or customer-specified color.
• Application of identification nameplate, QR code tag, and inspection stickers.
• Functional testing labels and serialized manufacturing records are affixed to the unit.
• Protective packaging including shrink film wrap, foam padding, and reinforced export-grade wooden crates.

Before shipment, each unit is subjected to a final quality audit checklist and verified for conformity with customer order specifications, electrical configuration, and mechanical layout.

Conclusion

The final assembly process ensures that every dry type transformer from Shinenergy is not only electrically and mechanically complete but also safe, robust, and ready for immediate field deployment. From cooling systems to enclosure finishing, every detail is engineered for long-term performance, safety, and reliability in real-world environments.

Testing & Quality Control 

Every dry type transformer produced by Shinenergy is subjected to 100% routine testing and comprehensive reliability evaluation to ensure performance, safety, and long-term durability. We operate a fully equipped in-house laboratory with both power frequency and high-frequency test systems, supplemented by multiple environmental and mechanical stress simulation platforms.

Routine Electrical Tests (100% on All Units)

These are conducted in accordance with IEC 60076, GB/T 10228, and client specifications:

In-House Testing Platform

Shinenergy’s dedicated test stations are equipped with:

High Frequency Testing System

• Capacity: 100 kVA
• Max voltage: 1200V
• Max current: 240A
• Frequency range: 2kHz – 40kHz

Power Frequency Testing System

• Capacity: 1000 kVA
• Max test current: 5000A
• DC bias test: up to 1500A (DPG mode)

These platforms support comprehensive product-level evaluation under both standard and simulated stress conditions.

Reliability Testing (Sampling or Upon Request)

To evaluate robustness under real-world and extreme conditions, we conduct a range of reliability and durability tests, either in-house or with certified third parties:

• Overload Test – Simulates operation under thermal/electrical stress
• Partial Discharge (PD) Aging
• Thermal Shock Test – Rapid heating/cooling to verify structural integrity
• Environmental Test – Temperature/humidity cycling
• Salt Spray Test – Corrosion resistance (for coastal or marine environments)
• Drop Test – Simulates handling and transport impact
• Potting Glue Adhesion Test – Ensures bonding of critical components
• Core Loss Test – Validates lamination and magnetic performance
• Vibration Shock Test – 3-axis mechanical endurance (via third party)
• IP Rating Certification – Enclosure protection level (via third party)

Quality Management & Traceability

• Batch tracking system for all coils, cores, and key materials
• Digital test reports including full electrical test values per unit
• Dual verification for critical parameters like winding resistance, PD, and loss
• Independent final QA audit prior to labeling and packaging

Summary

At Shinenergy, we treat testing not just as a checkpoint, but as a foundation for performance. From power frequency withstand tests to thermal shock and drop testing, our integrated testing platform ensures every dry type transformer is safe, compliant, and field-ready. Whether for data centers, transportation, renewables, or industrial plants, we deliver verifiable reliability you can trust.

Why Manufacturing Matters– Precision Engineering Drives Long-Term Performance

The performance and reliability of a dry type transformer are not only determined by design, but more importantly, by how well it’s made. At Shinenergy, we believe that every detail in the Transformer Manufacturing Process directly affects three critical dimensions of transformer performance:

Temperature Rise – The Foundation of Load Capacity

Even with the same insulation class, two transformers with different manufacturing precision may exhibit vastly different operating temperatures. Poor core stacking, loose windings, or uneven resin impregnation can lead to local hot spots, accelerated insulation aging, and thermal fatigue.

Through optimized coil winding tension, precise VPI resin penetration, and carefully calibrated cooling channel design, Shinenergy ensures all transformers operate at lower average temperature rise—enabling higher overload capacity and longer insulation life.

Losses – Efficiency Built Into Every Layer

Transformer losses are split between no-load losses (core) and load losses (windings). These are not just theoretical—they translate directly into energy cost over time. Even a 1% reduction in loss can save thousands of dollars in energy bills over a transformer’s lifecycle.

Our process emphasizes:

• CRGO silicon steel core cutting with low burr and tight tolerance
• Uniform conductor cross-section and spacing during coil winding
• Vacuum pressure impregnation for consistent dielectric path

This results in transformers with optimized core loss, copper loss, and low total harmonic distortion (THD). Especially in sensitive environments like data centers or industrial drives.

Service Life – Build Quality That Endures

Every mechanical vibration, thermal cycle, or environmental shock accumulates stress in the transformer. That’s why mechanical rigidity and moisture protection are just as important as electrical parameters.

Our full process—from core clamping torque control to anti-corrosion coating, from drop tests to salt spray simulations—is designed to deliver dry type transformers that survive real-world operational fatigue over 20+ years.

The Value to Customers

High-quality manufacturing doesn’t just protect against failures—it delivers clear long-term ROI:

• Lower maintenance frequency
• Energy savings from reduced loss
• Extended service life = delayed replacement cost
• Stable power quality for sensitive equipment

(Optional) Case Example – Industrial HVAC System Upgrade, Germany

A German building automation company replaced aging oil-immersed transformers with Shinenergy’s 400kVA dry type models. After 3 years of operation:

• Measured load loss reduced by 8%
• Average coil temperature dropped 12°C under same load
• No thermal alarms or partial discharge events recorded

“The quality of the manufacturing was visible from the moment it arrived—no adjustments needed, plug-and-play with stable readings since day one.”

— Chief Electrical Engineer, HVAC Systems GmbH

At Shinenergy, we don’t see manufacturing as a back-end task—it’s the core enabler of safety, efficiency, and durability. When you choose a transformer, you’re not just buying specs—you’re buying the sum of every production detail behind it.

Conclusion

In the world of dry type transformers, design sets the blueprint, but manufacturing defines performance.

At Shinenergy, we believe that every layer of insulation, every coil winding, every clamp torque, and every test point contributes to the transformer’s ability to perform reliably under real-world conditions. From core stacking and coil winding to vacuum pressure impregnation and final testing. We pay attention to every detail because reliability is built—not assumed.

Our manufacturing process is not just about passing a checklist—it’s about creating long-term value for customers who demand performance, safety, and operational stability in the most critical environments.

Ready to Explore More?

Whether you’re sourcing for industrial upgrades, infrastructure projects, data centers, or specialized OEM applications. Shinenergy’s engineering team is here to help.

• Contact our technical experts for custom solutions
• Request a detailed product selection guide or datasheet
• Schedule a visit to our manufacturing plant to see how quality is built from the inside out

Let’s turn precision into performance—together.