High-Efficiency Oil-Filled Distribution Transformers | CWS

Powering Industries with Reliable & Energy-Saving Solutions

CWS designs and manufactures high-performance distribution transformers (up to 1000 KVA / 1 MVA) for industrial, commercial, military and utility applications.

Types of Distribution Transformers

• Dry-type and oil-filled transformers
• Single-phase and three-phase configurations
• Voltage support from 120V to 22,900V

Transformer Technologies

1. Conventional Silicon Steel Core Transformers

• Grain-oriented silicon steel lamination
• Available as oil-filled (Mineral Oil or FR3) or dry-type
• Fail-safe construction with long service life

2. Amorphous Metal Transformers (AMT)

• 75% lower core losses using Metglas or nanocrystalline cores
• Ideal for variable load applications like renewable energy
• Preferred by industry leaders such as Shell Oil

Why Choose CWS Transformers?

• High Efficiency - Reduced core & copper losses
• Custom Designs - Tailored to industrial and utility needs
• Durability - Long-lasting dielectric fluids in oil-filled designs
• Future-Ready - Supports AMT technology for sustainability

Technical Specifications

Feature	Conventional (Si-Fe)	Amorphous (AMT)
Core Material	Grain-oriented silicon steel	Metglas/Nanocrystalline
Core Loss	Standard	75% Lower
Efficiency at Low Load	Moderate	Excellent
Size	Compact	Larger

Applications

• Utility distribution
• Military and industrial installations
• Oil & gas fields
• Renewable energy infrastructure

Medium Voltage Oil-Filled Transformers

MV oil-filled transformers operate from 2.4 kV to 34.5 kV and support up to 69 kV. Used in utilities, industry, and commercial power, they use mineral oil or FR3 esters for efficient insulation and cooling.

Primary Applications

• Utility distribution networks (e.g., 34.5 kV -> 4.16 kV)
• Industrial plants and commercial buildings
• Renewable energy grid interfacing

Typical Ratings

• Voltage Classes: 5-35 kV
• Power: 500 kVA to 20 MVA
• Cooling Types: ONAN, ONAF, KNAN

Advantages of Oil-Filled vs. Dry-Type

Feature	Oil-Filled	Dry-Type
Cooling	Better	Air-cooled
Voltage	Up to 345 kV	Up to 35 kV
Lifespan	30+ years	20-30 years
Cost	Lower for high ratings	Higher
Maintenance	Oil checks	Minimal
Fire Risk	Higher	Lower

Maintenance Practices

• Oil testing (DGA - Dissolved Gas Analysis)
• Infrared inspections
• Bushing and winding resistance checks
• Leak detection

Future Trends

• Biodegradable ester fluids
• IoT-based smart monitoring
• Compact, modular designs