Limitations of levitation by iron-cored electromagnets

We present simple "best-case" calculations of power/lift and lift/weight ratios for iron-cored electromagnetic levitation systems using either the attraction between controlled electromagnets and ferromagnetic guideway members or the repulsion between a.c. electromagnets and guideway conductors. Although power/lift ratios are low, the practical engineering restrictions of conductor current density, iron flux density and magnet size result in poor lift/ weight ratios and limit operation to low suspension heights.