Are you curious about what types of cores are available? As a manufacturer of transformer accessories, we have 20 years of experience and we have a deep understanding of core products. We offer EI cores for small transformers, as well as cores for large oil-immersed transformers, as well as other C-type cores, amorphous cores, etc. When choosing a transformer core for your application, choosing the right core construction type (EI Core or C Core) can have a significant impact on efficiency, performance, and production costs. Both are widely used in power transformers, inductors, and magnetic components, but they differ in structure, magnetic properties, and ease of assembly.
1. What Is an EI Core?
An EI Core is made up of two types of laminations: "E" shaped and "I" shaped sheets. These laminations are stacked together to form a closed magnetic circuit. It's one of the most commonly used core structures in transformer manufacturing.
-Features of EI Core:
Made from silicon steel, amorphous, or nanocrystalline material
Low cost and easy to mass-produce
Widely used in power transformers, control transformers, and small inductors
Ideal for 50Hz–400Hz applications
2. What Is a C Core?
A C Core is typically made from rolled strips of silicon steel, amorphous, or nanocrystalline material, cut into a "C" shape and paired to form a closed magnetic loop. Unlike EI cores, C cores have fewer air gaps and higher magnetic continuity.
-Features of C Core:
Fewer joints = lower core losses and noise
Better for medium-frequency or energy-efficient applications
Easy to open and close for coil insertion
Often used in current transformers, audio transformers, and high-efficiency power systems
EI Core vs. C Core: A Practical Comparison
| Feature | EI Core | C Core |
|---|---|---|
| Structure | Laminated E and I sheets | Two half "C"-shaped blocks |
| Magnetic Loss | Higher due to air gaps | Lower due to better continuity |
| Assembly | Needs stacking and lamination | Easier to insert coils |
| Cost | Lower, ideal for mass production | Higher, more material waste in cutting |
| Applications | General-purpose transformers, control units | High-efficiency transformers, CTs |
| Frequency Range | 50Hz–400Hz (standard) | 50Hz–10kHz (with amorphous or nanocrystalline) |
| Customization | More flexible with punch-mold process | Limited size options, but high performance |
Which One Should You Choose?
1.Choose EI Core if your project prioritizes cost-effectiveness, standard frequency, and high-volume manufacturing. It's ideal for power transformers, small to medium capacity.
2.Choose C Core if you need higher efficiency, lower loss, and easier coil mounting. It's ideal for high-performance, low-noise, or high-frequency equipment.
For energy-saving transformer designs, we also recommend Amorphous C Cores, which reduce core losses by up to 70% compared to traditional silicon steel.
We Manufacture All Types of Transformer Cores
As a transformer core manufacturer, we offer:
- EI Cores: in various sizes and materials, including cold-rolled silicon steel, amorphous, and nanocrystalline
- C Cores: custom and standard, for energy-efficient or audio-frequency applications
- Toroidal Cores: for compact, low-leakage transformer designs
- Amorphous Cores: for distribution transformers, energy saving
- Core Assemblies: for oil-immersed transformer tanks