The Birth of A Dry-type Transformer

• Core Construction: The Transformer's 'Skeleton'
  The core is the heart of the transformer's magnetic circuit. Its quality directly impacts the transformer's no-load loss and noise level.

• Material Selection & Cutting: High-quality cold-rolled grain-oriented silicon steel is typically used. This is often laser-etched to help reduce hysteresis losses. The steel is then cut to the required shape and dimensions using a cutting line.

• Stacking & Clamping: Modern processes often use "step-lap" stacking and a 45-degree fully mitered joint structure. This effectively reduces losses at the joints and the air gaps, thereby lowering no-load loss, no-load current, and core noise. The assembled core is securely clamped with special fixtures and is sometimes coated with a moisture and rust-resistant material.

  
  

• Coil Winding & Insulation: The Transformer's 'Heart'
  The windings form the electrical circuit of the transformer, making their manufacturing process critical.

• Winding Process: High-voltage (HV) windings are typically wound using high-speed winding machines to ensure concentricity and tightness, which is crucial for the transformer's short-circuit withstand capability. Depending on the capacity and voltage, low-voltage (LV) windings may be foil-wound or wire-wound.

• Tap Leads: The tap leads for the HV winding must be precisely positioned according to the design, with correct length, soldering, and reliable insulation wrapping to prevent issues like short circuits or assembly problems.

  
  

• ️ Insulation Processing: The Critical 'Protective Layer'
  This stage is especially critical for resin-cast dry-type transformers.

• Pre-Drying: The windings and other insulation components are pre-dried before casting to remove moisture.

• Vacuum Resin Casting: This involves pouring a mixed epoxy resin compound into a mold containing the windings under a vacuum environment. The vacuum removes air bubbles, ensuring the resin penetrates completely and forms a dense insulation system, which is key to controlling partial discharge.

• Curing: After casting, the unit is heated under a strictly controlled temperature profile to cure the resin. Proper casting and curing ensure the transformer is resistant to moisture, fire-proof, and has high mechanical strength.

  
  

• ⚙️ Assembly & Testing: The Final 'Health Check'
  This involves assembling the insulated windings, core, and other components.

• Turns Ratio Measurement & Winding Resistance Test

• No-Load Loss & Load Loss Test: Verifies energy efficiency levels. For instance, an SCB13-type dry-type transformer has significantly lower no-load and load losses compared to older models.

• Applied Voltage & Induced Voltage Withstand Tests: Checks the main and inter-turn insulation strength.

• Partial Discharge Test: Advanced manufacturing processes can result in very low partial discharge levels.

• Core & Coil Assembly: The core and coils are assembled, and internal connections are made.

• Final Assembly & Attachment Installation: This includes installing cooling fans, temperature control devices, protective enclosures, etc.

• Routine Tests: These are essential to ensure the transformer meets standards and design specifications. 

  
  

• Packaging & Shipping
  Finally, based on the transformer's size and shipping distance, appropriate packaging materials and methods (e.g., wooden or steel crates) are selected to ensure the product is protected from damage during transit.

Summary

In essence, the creation of a high-quality dry-type transformer is the result of the combined effect of design, materials, craftsmanship, and quality control. The manufacturer's meticulous attention to material selection (e.g., high-grade silicon steel, high-conductivity copper, quality insulation) and every manufacturing process (e.g., core stacking, coil winding, insulation processing) collectively guarantees the final product's performance and reliability.