The performance of nanocrystalline  core is determined by the  permeability of the strip used for the core and the size of the core (OD, ID, H)

• Derived from OD, ID, height H
• Cross sectional area of magnetic core：S = 1 / 2 (OD-ID) *H
• Magnetic circuit length L = π / 2 * (OD + ID)

Due to the gap between the strip layers in the process of core winding, the effective cross-sectional area

Se=f*S

If is the lamination coefficient or filling factor, which represents the proportion of metal materials in the actual core

Therefore, the performance of the magnetic core depends on Se and L

And the core weight W= ρ* Ve= ρ* Se*L

ρ Ideal density of nanocrystalline materials

Ve effective volume of core

When quoting, we usually choose f = 0.75 as the lamination coefficient according to the quality of the strip

During some production, the strip is relatively smooth, and the lamination coefficient reaches f = 0.80. Therefore, we only control the weight of the material during production, maintain the same effective cross-sectional area, and reduce the outer diameter when the inner diameter remains unchanged, please use these cores to test whether they have the enough performance for transformer.