Abstract: A high-efficiency self-regulated electronic ballast with a single characteristic curve for operating high-pressure sodium vapor lamps by means of an AC-to-DC converter circuit, a power factor correcting regulator circuit for reducing harmonic distortion, a high-frequency DC-to-AC converter circuit, a reducing autotransformer circuit with a current limiting inductor and an igniter, and a light-controlled switching circuit. The ballast is characterized in that it supplies a controlled high-frequency alternating voltage to the assembly of the limiting inductor and the lamp, whereby the ballast has a single characteristic curve, and in that the average power consumption of the lamp is determined on the basis of the single characteristic curve of the ballast within the standard regulation trapezoid defining the average consumption of the ballast/lamp assembly.