Transformer Manufacturing Process

The performance of any transformer begins with its magnetic core. KROS Electric Co., Ltd. utilizes high-grade Cold-Rolled Grain-Oriented (CRGO) silicon steel laminations, including Hi-B and laser-scribed grades sourced from tier-1 steel manufacturers worldwide.

Our automated shearing and step-lap core stacking technique ensures ideal magnetic flux distribution, drastically reducing core losses, excitation current, and acoustic noise levels.

• Precision multi-step lap miter joints for minimal flux distortion.
• Insulated lamination coating preventing eddy current losses.
• Rigid channel clamping ensuring zero vibration during continuous load.

We engineer High Voltage (HV) and Low Voltage (LV) coils using 99.99% pure electrolytic copper conductors. Coils are wound on automated precision winding machines under climate-controlled dust-free conditions to achieve strict dimensional accuracy.

Depending on electrical requirements, disc, helical, or cross-over winding configurations are applied with high-density pressboard insulation to easily withstand transient overvoltages and thermal expansions.

• Oxygen-free electrolytic copper with high conductivity.
• Thermally upgraded pre-compressed pressboard insulating materials.
• Optimized cooling ducts for uniform oil circulation and heat dissipation.

During active part assembly, the core, HV/LV windings, tap changers, and insulation structures are integrated into a single unified structure. Calculated axial and radial mechanical pressure is applied using torque-calibrated tie-rods and heavy steel end frames.

This rigid construction guarantees that KROS Electric transformers withstand severe electrodynamic stresses occurring during external short-circuit fault conditions.

• Calibrated mechanical clamping for short-circuit strength.
• Short lead connections to reduce stray losses and inductance.
• Rigid tap changer alignment for smooth ratio switching.

Moisture is the primary enemy of transformer solid insulation. Our state-of-the-art vacuum drying plant subjects the assembled active parts to high thermal processing combined with deep vacuum evacuation down to millibar levels.

This process completely eliminates residual moisture trapped deep inside paper insulation, dramatically elevating dielectric strength and prolonging operational service lifespan beyond 30+ years.

• Computer-monitored cycle time and vacuum level parameters.
• Elimination of air pockets and moisture to prevent partial discharge.
• Enhanced insulation power factor and insulation resistance values.

Transformer tanks are fabricated from heavy-gauge structural steel plates, shot-blasted to remove oxidation, and coated with multi-layer corrosion-resistant polyurethane paint systems. Tanks undergo stringent pressure-leak tests to ensure hermetic integrity.

Immediately after drying, active parts are placed inside tanks and filled with ultra-pure, degassed transformer insulating oil under deep vacuum conditions, preventing moisture re-absorption.

• Shot-blasted anti-corrosion tank surface treatment for harsh environments.
• Pressure and vacuum leak tested to prevent oil seepage.
• De-aerated oil filling for maximum dielectric breakdown voltage (BDV).