How an EMINSA transformer is built
From planning and design to final electrical testing, our manufacturing process is documented, controlled, and validated at every stage to ensure quality and compliance with IEEE/ANSI standards.
9 stages, 1 reliable transformer
Each unit goes through a structured, controlled, and documented process with Control Plan verification at every station, from raw materials to labeling and dispatch.
1Stage 1 of 9Electrical and mechanical design
Planning and Design
The process begins with the opening of the production order. The electrical design team defines all electrical characteristics of the transformer, and the mechanical design department develops its structural design based on those specifications. The software loads the complete model with the Bill of Materials for all supplies.
- Opening of production order (Planning)
- Software: model loading and Bill of Materials with all supplies
- Electrical Design: complete electrical characteristics of the transformer
- Mechanical Design: structural design based on electrical specifications
- Design review vs. quality controls before proceeding
2Stage 2 of 9LV and HV Station
Raw Material Inspection and Winding
Before starting the winding, a thorough review of raw materials is performed. Then insulating paper cutting and form manufacturing proceed, followed by low and high voltage winding with strict controls on number of turns, conductor mechanical tension, and interlayer insulation.
- Raw material inspection: magnetic lamination thickness and grade
- Verification of copper/aluminum certificates and insulation integrity
- Insulating paper cutting and form manufacturing (dimensional precision ± tolerance per drawing)
- Low Voltage (LV) Winding: number of turns, conductor mechanical tension, interlayer insulation
- High Voltage (HV) Winding: same critical quality controls
- Verification of Control Plan compliance before proceeding
3Stage 3 of 9Core cutting and assembly station
Magnetic Core Cutting and Assembly
The magnetic core is cut with controlled dimensional precision, verifying that burrs are below the permitted limit and that the lamination sequence is correct. Then the core is stacked and assembled with Step-Lap alignment, uniform compression, and specified clamping torque.
- Magnetic Core Cutting: dimensional precision (± specified tolerance)
- Burrs < permitted limit and correct lamination sequence
- Core Stacking and Assembly: Step-Lap alignment
- Uniform compression and clamping torque per specification
- Verification of Control Plan compliance before proceeding
4Stage 4 of 9Transport, pressing, and oven
Coil Pressing and Drying
Finished coils go through the Coil Pressing process, where the final measured height is controlled while respecting the nominal LV and HV dimensions. They then enter the drying oven at temperatures between 90 °C and 110 °C as designed for 12 hours, recording results in the oven temperature control checklist.
- Coil Pressing Process: avoid applying excessive force, verify final measured height
- Respect nominal LV and HV height of assembled coil; final measurement documented
- Transport of pressed coil to oven
- Oven parameters validated before loading the coil
- Coil Drying: 90 °C – 110 °C as designed, 12 hours
- Recording of results upon exiting oven in the 'Oven Temperature Control, Operational Checklist'
5Stage 5 of 9Core insertion, flange, and connections
Active Part Assembly (Pre-Tank)
The core is inserted and assembled into the coils with focus on axial centering, radial spacing, and mechanical fit. The flange is installed verifying the surface, gasket, and torque. Finally, external connections prior to tanking are made, correctly identifying terminals and respecting dielectric distances.
- Core insertion and/or assembly into coils: axial centering, radial spacing, mechanical fit
- Flange Installation: surface inspection, gasket verification, torque control
- External Connections Prior to Tanking: correct terminal identification
- Torque on bolted connections and dielectric distances verified
- Verification of Control Plan compliance before proceeding
6Stage 6 of 9Parallel process — cutting, welding, and painting
Tank Metalwork
In parallel with active part manufacturing, the metalwork department fabricates the tank through laser cutting of plates, forming/bending of walls and cover, complete structural welding, and surface preparation. After leak testing and dimensional inspection, the tank receives its paint system (primer, intermediate coat, and finish) and final mechanical inspection before being released by Quality.
- Laser Machine Cutting: pre-start inspections (Kick-off Checklist), cutting and dimensional verification
- Forming / Bending: shaping of sidewalls, cover, and dimensional inspection
- Complete Welding: structural welds, nozzle flanges, and reinforcements
- Grinding and surface preparation: weld smoothing, burr removal, cleaning
- Leak Test: air pressure test, soapy solution inspection, retention time
- Dimensional Inspection: tank height, flange flatness, radiator alignment, bolt hole positions
- Surface Preparation: sandblasting / shot blasting, roughness and cleanliness verification
- Paint Process: primer application, intermediate coat, final coat, and curing time control
- Final Mechanical Inspection: visual, dimensional, paint thickness report, leak test approval, and Quality release
7Stage 7 of 9Tank reception and tanking
Tanking
Once the tank is released by Quality (painted and cured), it is transported to the tanking area.
- Tank Reception from Metalwork (painted, cured, and released by Quality)
- Transport of approved tank to the tanking area
- Integration of the active part inside the tank
- Verification of Control Plan compliance
8Stage 8 of 9Oil Treatment & Tank Filling
Oil Treatment and Vacuum Filling
The dielectric oil is filtered and vacuum is applied to the tanked transformer. The vacuum filling process ensures complete insulation impregnation and the absence of air bubbles. The Oil Filtered & VA Vacuum and Oil Filling Visual Aids are followed.
- Oil Filtered: dielectric oil filtering and treatment
- VA Vacuum: vacuum application to the transformer before filling
- Oil Filling: vacuum filling for total insulation impregnation
- Following Visual Aids 'Oil Filtered & VA Vacuum and Oil Filling'
- Verification of Control Plan compliance before proceeding to testing
9Stage 9 of 9Testing, Inspection & Packaging
Electrical Testing, Final Inspection, and Dispatch
Each transformer undergoes a complete electrical testing protocol per IEEE C57 at the testing station. Once results are approved (Pass), cabinet assembly, final inspection and packaging, and finally labeling and packaging for dispatch proceed.
- Testing & Results: complete electrical tests per IEEE C57
- Verification of Control Plan compliance in testing
- Cabinet Assembly (approved by Control Plan)
- Final Inspection & Packaging: visual, dimensional, and finish inspection
- Labeling and Packaging: nameplate, packaging for transport and dispatch
Documented quality at every stage
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