A superposition method is developed to calculate electrodynamic separators with a travelling magnetic field. The general solution is obtained by adding several more simple solutions in one-dimensional and two-dimensional terms. A one-dimensional mathematical model of a linear asynchronous motor is regarded as a basic one. Several equations are derived to make necessary calculations. The method developed has been successfully tested in comparing with the results of the experimental investigation of separators int he wide frequency range of reversal magnetization (30-1000 Hz), with a great variety of relationships between plates and separators.