How Do Different Cores Impact Transformer Functionality?

Transformers are one of the most crucial elements in the vast network of electrical power systems, serving as the silent workhorses that ensure the efficient transmission and distribution of electrical energy. The core of a transformer plays a crucial role in its functionality, affecting its efficiency, performance, and overall effectiveness. Hence, in this blog, we will explore several common types of transformer cores on the market, unveiling their impact on the performance of these indispensable machines.

1. Silicon Steel Iron Cores

Silicon steel is the most commonly used material for transformer cores. It is an alloy of iron with a small percentage of silicon, which enhances its magnetic properties. Generally, it is available in two main grades:

Grain-Oriented (GO) Silicon Steel: designed with a specific grain structure that enhances magnetic properties This type of core effectively reduces hysteresis and eddy current losses, making it suitable for power transformers and low-frequency applications.

Non-Grain-Oriented (NGO) Silicon Steel: usually exhibits uniform magnetic properties in all directions, typically used in applications where the magnetic flux is more random or multi-directional, like toroidal transformers.

2. Ferrite Cores

Ferrite cores are made from a mixture of iron and various metal oxides, which results in a material with high electrical resistance.

This characteristic allows ferrite cores to exhibit lower hysteresis losses compared to their magnetic counterparts. Additionally, ferrite cores can be molded into intricate shapes, allowing for compact and lightweight transformer designs.

However, it needs attention that ferrite cores are not ideal for low-frequency applications, as their permeability decreases significantly at lower frequencies. They are commonly found in applications such as switch-mode power supplies, telecommunications, electronic ballasts, and radio frequency (RF) transformers.

3. Amorphous Metal Cores

Amorphous steel, or metallic glass, is an innovative core material that is increasingly used in transformers due to its superior energy efficiency.

Unlike conventional crystalline steel, which has a regular atomic structure, amorphous steel has a disordered atomic structure that reduces the magnetostriction effect — an undesirable property where the material changes shape under magnetic influence. This reduction in magnetostriction leads to lower energy losses and higher efficiency. A well-designed amorphous transformer core shows:

Extremely low hysteresis losses (up to 70% less than silicon steel transformer core)

Higher efficiency, especially at light loads

More brittle and harder to work with than crystalline metals

Therefore, amorphous metal cores are mainly applied in:

Applications:

High-efficiency distribution transformers

Green energy applications

Where energy savings justify higher initial costs

As the demand for more sustainable energy solutions grows, the use of amorphous steel cores in transformers would have a lot of room for development.

4. Powdered Iron Cores

Powdered iron cores are made from tiny particles of iron that have been powdered and then pressed together under heat and pressure to form a solid core. This core material is typically mixed with insulating materials to create a composite that optimizes its magnetic properties and minimizes losses. In general, the particle size, density, and the type of insulation used can be varied to tailor the core’s performance for specific applications. Powdered iron cores can impact the transformer’s functionality in terms of:

Efficiently channel magnetic field lines, contributing to better transformer and inductor performance.

Lower saturation point compared to ferrite or silicon steel, which can handle a moderate range of flux densities.

Reduce eddy current losses because of the insulation between the particles.

Applications:

Inductors in switching regulators

RF transformers

Noise filter chokes

Buck and boost converters

Summary

Transformer cores play a critical role in determining the performance and efficiency of transformers. Magnetic cores, commonly made from silicon steel, offer excellent magnetic properties, making them ideal for power distribution transformers. Ferrite cores and powered iron cores are preferred for high-frequency applications, while amorphous cores significantly reduce eddy currents and hysteresis losses, widely used in energy-efficient transformer applications.

By selecting the appropriate core, engineers can optimize the performance and efficiency of transformers, ensuring reliable and safe power transmission across various applications.