Cast Coil Dry Type Transformer Structure

1. Core Component 1: Iron Core – The Magnetic Circuit Backbone

(1) Material Selection

(2) Structural Types

• Core-Type Iron Core (Most Common):
  • Composed of iron core columns (where windings are sleeved), iron yokes (connecting the top/bottom of core columns), and clamping devices (steel plates + bolts to fix the core).
  • Advantages: Simple structure, easy winding assembly, and lower material consumption. CHH Power’s 30kVA–300kVA dry-type transformers (e.g., SCB13 series) all use this structure, suitable for general industrial and commercial power distribution.
• Shell-Type Iron Core:
  • The iron core surrounds the winding on all four sides, like a “shell” protecting the winding.
  • Advantages: High mechanical strength (resistant to short-circuit forces). However, it has a complex manufacturing process and higher material costs, so CHH Power only uses it for special scenarios (e.g., high-voltage dry-type transformers for power transmission).

(3) CHH Power’s Optimization

2. Core Component 2: Winding – The Circuit Core

(1) Material & Insulation

• Conductor: CHH Power primarily uses high-purity oxygen-free copper wires (99.95% purity) for windings. Copper has lower resistivity than aluminum, reducing load loss (energy loss during operation). For cost-sensitive scenarios, CHH Power also provides aluminum wire windings with optimized cross-sections to ensure performance.
• Insulation: Windings are wrapped with Class F or H heat-resistant insulating materials (e.g., epoxy resin, polyimide film). These materials withstand temperatures up to 155°C (Class F) or 180°C (Class H), ensuring safe operation even in high-temperature environments (e.g., indoor power distribution rooms with poor ventilation).

(2) Structural Types

• Concentric Winding (Mainstream):
  • HV and LV windings are concentrically sleeved on the iron core column. The LV winding (with smaller insulation requirements) is placed inside, and the HV winding is outside.
  • Advantages: Compact structure, uniform magnetic flux distribution, and low leakage inductance. Used in CHH Power’s standard dry-type transformers (e.g., 10kV/0.4kV 200kVA models).
• Overlapping Winding (Special Scenarios):
  • HV and LV windings are arranged in layers along the axial direction of the iron core column, overlapping each other.
  • Advantages: Smaller axial size, suitable for transformers with strict height limits (e.g., underground substations). CHH Power customizes this structure for specific project needs.

(3) CHH Power’s Manufacturing Control

3. Key Auxiliary Components (Dry-Type Transformer-Specific)

(1) Insulation Bushings

• Function: Isolate and support the winding leads, allowing them to safely pass through the transformer enclosure and connect to external circuits.
• CHH Power’s Design: Uses epoxy resin insulation bushings (for medium voltage) or silicone rubber bushings (for high voltage). These bushings have high dielectric strength (≥30kV/mm) and good moisture resistance, suitable for indoor and semi-outdoor environments.

(2) Cooling System

• Natural Air Cooling (AN): For small-capacity transformers (≤100kVA). Heat generated by the iron core and windings is dissipated naturally through convection and radiation.
• Forced Air Cooling (AF): For medium-to-large capacity transformers (≥150kVA). CHH Power installs axial cooling fans (with temperature control) on the transformer enclosure. When the winding temperature exceeds 100°C, the fans start automatically, increasing cooling efficiency by 30% and allowing the transformer to handle 120% of rated load for short periods.

(3) Temperature Control & Protection System

• Function: Monitor winding temperature in real time and trigger protection measures to prevent overheating.
• CHH Power’s Configuration: Equips a three-phase winding temperature controller with:
  • Real-time temperature display (accuracy ±1°C).
  • Automatic fan control (start/stop based on temperature).
  • Over-temperature alarm (130°C) and tripping (150°C) functions, ensuring the transformer shuts down safely if temperatures are too high.

(4) Enclosure

• Function: Protect internal components from dust, moisture, and mechanical impact; reduce operational noise.
• CHH Power’s Options:
  • IP20 Enclosure: For indoor use (prevents 12.5mm+ solid object intrusion).
  • IP23 Enclosure: For semi-outdoor use (adds rainproof design).
  • Material: Cold-rolled steel sheet (painted with anti-corrosion coating) or stainless steel (for corrosive environments, e.g., coastal areas).

4. CHH Power’s Structural Advantages

1. High Efficiency: Low-loss silicon steel cores and copper windings reduce no-load and load losses, meeting Class 1 energy efficiency standards.
2. Safety & Reliability: Oil-free design eliminates fire and leakage risks; Class H insulation and temperature protection ensure long-term stable operation (service life ≥20 years).
3. Flexibility: Customizable enclosures, cooling systems, and voltage ratios adapt to diverse scenarios (e.g., data centers, hospitals, industrial plants).