Core loss: what it is and how to specify it
Core loss is the power dissipated as heat when the core is magnetised, measured in W/kg at a defined frequency and flux density (e.g. 1.5 T at 50 Hz). Lower loss means less heating and higher efficiency. For grain-oriented silicon steel, loss depends mainly on grade thickness and domain refinement; for nanocrystalline it is roughly an order of magnitude lower at high frequency.
What determines core loss
Material: grain-oriented (GOES) grades are specified by loss at 1.7 T/50 Hz, e.g. 23Q110, 27Q100, 30Q120 — the number roughly indicates W/kg × 100.
Thickness: thinner strip (0.23 mm vs 0.30 mm) reduces eddy-current loss but costs more and is harder to cut.
Frequency: hysteresis loss scales with f, eddy loss with f². Above a few kHz, ferrite or nanocrystalline wins.
Stress: cutting and winding introduce stress; annealing after cutting restores loss to near material values.
How to state a requirement
Give frequency, flux density, allowable temperature rise and annual quantity. We then recommend grade, thickness and whether annealing is required.
FAQ
Is lower core loss always better?
Not always — thinner, higher-grade steel costs more. Balance loss against material cost and the value of saved energy over the product life.
