Eddy Current Loss Calculator
Enter lamination thickness, frequency, flux density, stack volume and core constant to compute eddy-current (iron) loss P_e = K_e·f²·B²·t²·V (W).
Input Data
Results
At a glance:In an iron core, a changing magnetic field induces closed loops of eddy current that meet resistance and dissipate as heat — eddy-current loss (a part of iron/core loss). Classic formula P_e = K_e · f² · B² · t² · V, where K_e is a core constant (set by resistivity and unit choices), f the frequency, B the peak flux density, t the lamination thickness and V the core volume. Loss rises with the square of each of f, B and t, so thin laminations (or ferrite) cut it sharply; stacking plates with their planes perpendicular to the field breaks the eddy loops and is the standard fix.
Formula
Eddy loss: P_e = K_e · f² · B² · t² · V (W).
Loss density: W/kg = P_e ÷ (ρ·V) with ρ the core density.
Lamination rule: halving t cuts eddy loss to ¼.
$$P_e = K_e f^2 B^2 t^2 V$$$$w = \frac{P_e}{\rho V}$$How to Use
- Enter core constant K_e, frequency f, flux density B, lamination thickness t and core volume V.
- The tool returns eddy loss P_e and loss density, and a lamination note.
Case Studies
Transformer lamination comparison
K_e=1, f=50Hz, B=1T, V=0.001m³; t=0.5mm → P_e = 1×2500×1×0.00000025×0.001 ≈ 0.625W.
If t is halved to 0.25mm, P_e falls to ≈ 0.156W (¼) — thin laminations pay off fast.
At 60Hz instead of 50Hz the loss rises to ≈ 0.90W (×1.44), showing the f² dependence.
FAQ
Why laminate the core?
Eddy currents circulate in the plane perpendicular to the field. Stacking thin plates with their broad faces normal to the field cuts each loop's area, and thinner plates cut it further (loss ∝ t²), shrinking the induced current and heating.
Why does loss scale with frequency squared?
Faraday induction ∝ f gives an induced voltage ∝ f; eddy current ∝ f and I²R loss ∝ current², so power loss ∝ f². Same for B² (larger swing induces larger current).
Is this the whole iron loss?
No. Total iron loss = hysteresis loss + eddy-current loss; this tool computes the eddy part. Hysteresis depends on the B–H loop and frequency (≈ f·B^n); designers sum both for core loss.
Why use ferrite?
Ferrite has very high resistivity, so eddy currents are tiny and it suits high-frequency (switch-mode, RF) magnetics where laminated steel would overheat; its lower B saturates easily, so it is for high-f low-B use.
How does thickness change the optimum?
Thinner laminations cut eddy loss but add count, cost and stacking-factor (air gap) losses; very thin foil can also raise hysteresis. Pick thickness for the operating frequency and B per core-material datasheets.
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References
Content review: Calculatorism Science Team. Results are for reference only; please refer to the relevant authorities for the official figures.