High Permeability Iron Core Toroidal Transformer
Oct 15, 2025
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toroidal iron core
A toroidal iron core is a common magnetic component made of magnetic materials in a closed toroidal structure. It is widely used in electromagnetic devices such as transformers and inductors.
It is usually made of soft magnetic materials with high magnetic permeability, such as silicon steel sheets, amorphous alloys, or ferrites. These materials feature low hysteresis loss and eddy current loss, which enhance the efficiency and reliability of power electronic equipment.

ring core Feature
- Closed Magnetic Circuit: The magnetic circuit of a toroidal iron core is closed without air gaps. This results in low magnetic reluctance, which effectively reduces magnetic losses, ensures uniform magnetic flux distribution, and avoids flux concentration caused by air gaps in traditional iron cores.
- Symmetry: The toroidal iron core has a high degree of geometric symmetry. This symmetry makes the magnetic field distribution inside the core more uniform, enabling better electromagnetic coupling and improving the efficiency of the device.
- Low Magnetic Leakage: Due to the closed magnetic circuit without air gaps, the toroidal iron core has minimal magnetic leakage. This not only reduces energy loss but also minimizes interference with external circuits.
toroidal core Advantages
- Low Loss: The soft magnetic materials used in toroidal iron cores have low hysteresis loss and eddy current loss. They can still maintain high efficiency at high frequencies, making them suitable for high-frequency switching power supplies and inverters.
- High Magnetic Permeability: High magnetic permeability means the core can withstand higher magnetic flux density. This reduces the volume and weight of the core, facilitating the miniaturization and lightweight design of power electronic equipment.
- Low Noise: The closed magnetic flux path of the toroidal iron core ensures uniform magnetic flux density distribution. As a result, it generates low electromagnetic noise during operation, making it suitable for noise-sensitive applications such as audio amplifiers and communication devices.
Transformer core Application
Uninterruptible Power Supply (UPS):
Used as isolation transformers and energy storage inductors in UPS systems. It can provide a stable output voltage to ensure the normal power supply of loads.
Inverters:
Applied in inverters of solar photovoltaic systems and electric vehicle charging stations to convert direct current (DC) to alternating current (AC). Its efficiency and low-loss characteristics help improve the overall performance of the inverter.
Switching Power Supplies:
Serves as transformers and filter inductors in switching power supplies. It enables energy conversion at high frequencies, reduces the size and weight of the power supply, and enhances conversion efficiency.
Audio Amplifiers:
Used as audio transformers in audio equipment. It can effectively isolate grid interference, provide a pure audio signal, and ensure pure and natural sound quality.
toroidal core specification
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| Magnetic core size(mm) | Protective box size(mm) | Effective cross-sectional area Ae(mm2) | Magnetic path length Ie(mm) | Maximum DC overcurrent class (A) |
||||||
| id | od | ht | ID | OD | HT | |||||
| 14 | 19 | 6.5 | 12 | 22 | 8 | 11.86 | 51.81 | 20 | ||
| 14 | 20 | 10 | 12 | 22.3 | 11.4 | 29.68 | 52.29 | 40 | ||
| 16 | 21 | 10 | 15 | 24 | 12.3 | 24.85 | 57.41 | 60 | ||
| 16 | 23 | 8 | 15 | 24 | 9.7 | 20.44 | 61.23 | 60 | ||
| 16 | 23 | 10 | 15 | 24 | 12.3 | 34.62 | 59.92 | 60 | ||
| 17 | 22 | 10 | 15.3 | 24.4 | 12.3 | 24.86 | 60.59 | 60 | ||
| 17 | 21 | 8 | 15.3 | 24 | 9.7 | 25.56 | 60.67 | 60 | ||
| 17 | 23 | 8 | 15.3 | 24.4 | 9.7 | 26.89 | 61.34 | 60 | ||
| 18 | 23 | 10 | 16.4 | 24.4 | 12.3 | 29.78 | 60.38 | 70 | ||
| 18 | 24 | 9 | 16.4 | 25 | 11.2 | 34.78 | 60.89 | 70 | ||
| 18 | 25 | 10 | 16.4 | 25.9 | 12.3 | 37.97 | 64.56 | 70 | ||
| 19 | 24 | 9 | 17.3 | 25 | 11.2 | 40.39 | 65.32 | 80 | ||
| 19 | 25 | 10 | 17.3 | 26 | 12.3 | 39.42 | 62.31 | 80 | ||
| 19 | 26 | 10 | 17.3 | 27.3 | 12.3 | 48.32 | 69.56 | 80 | ||
| 20 | 25 | 10 | 18.5 | 26.3 | 12.3 | 39.29 | 70.32 | 90 | ||
| 20 | 28 | 10 | 18.5 | 29 | 12.3 | 45.76 | 73.88 | 90 | ||
| 20 | 32 | 10 | 18.5 | 32.3 | 12.3 | 58.91 | 78.75 | 90 | ||
| 21 | 29 | 10 | 18.2 | 31.3 | 12.3 | 39.65 | 77.19 | 100 | ||
| 21 | 26 | 8 | 18.3 | 27.4 | 9.7 | 46.54 | 78.32 | 100 | ||
| 21 | 28 | 10 | 18.3 | 30 | 12.3 | 50.39 | 77.45 | 100 | ||
| 22 | 28 | 10 | 20.5 | 30 | 12.3 | 49.32 | 79.89 | 120 | ||
| 22 | 32 | 10 | 20.5 | 33.4 | 12.3 | 43.58 | 73.43 | 120 | ||
| 23 | 32 | 10 | 21.3 | 33.4 | 12.3 | 44.56 | 74.56 | 120 | ||
GNEE Featured Products
Gnee provides premium iron cores to the world. Our cores can be selected in a wide range of materials, shapes, applications, manufacturing techniques, etc., to meet customers' diverse demands. Explore our wide product range now~
Manufacturing Process

1. Raw Material Sourcing

2. Slitting

3. Punching

4. Laminating

5. Core Forming

6. testing
GNEE EC
Founded in 2008 and located in Anyang in China, Gnee Electric is a high-tech enterprise specializing in researching and manufacturing iron core products.
The company currently occupies over 20,000 square meters and employs more than 200 people, including over 80 professionals. After more than 18 years of development, we have built our own magnetic material production base and independently develope, produce, and sell various kinds of iron cores. The common types include silicon steel cores, motor cores, transformer cores, toroidal iron cores, special-shaped cores, custom cores, and others. Our cores are widely applied in different sectors including transformers, motors, mutual inductors, voltage stabilizers, welding machines, magnetic amplifiers, and instrumentation, providing diverse core solutions to global customers.

30+
Types of Products
18k+
Happy Clients
Why Choose GNEE EC?
GNEE EC was founded in 2008, which is a National High-tech Enterprise & Famous Brand Enterprise in China, developing into a professional manufacturer and supplier of high-quality iron cores.
18+
Over 18 years of success in the iron core industry;
National High-tech Enterprise & Famous Brand Enterprises in China;
200+
Over 200 employees;
The R&D team has more than 80 experienced engineers and the production team has more than 100 skilled staffs;
35+
Annual turnover up to 35 million dollor per year;
Owns many sets of highly automatic winding, annealing, and assembling machines;
1,000+
Over 1000 customers in domestic and overseas markets;
core Products are exported to more than 70 countries in the world;
Gnee Iron Core Factory Overview






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