The article describes the equivalent circuit of a jointless rail circuit with one throttle transformer and derives equations for the analysis and synthesis of rail circuits when powered on one side. A mathematical model and analytical expressions are developed taking into account the resistance of the rails and the resistance of the insulation. The coefficients of a rail four-poul with one throttle transformer supply voltage on the one hand. The calculated expressions of the four-terminal devices and the sensitivity criteria of the rail circuit when a single line breaks, as well as the minimum transmission resistance, are presented and derived
