Abstract: A regulator includes a switching transformer (TR) whose primary winding is divided into two halves through which current flows alternatingly via one respective switching transistor (Q1, Q2). The pulses on the secondary side of the transformer are rectified to attain the output voltage. The output voltage is controlled by pulse width modulated driver pulses for the two switching transistors. A protective circuit (12) with immediate effect terminates the currently applied driver pulse when the current flowing through the conductive switching transistor reaches a critical current value. A protective circuit (14) with delay effect prevents the generation of further driver pulses upon a further increased overload, this prevention being limited with respect to time. The protective system directly is controlled by the primary current of the power regulator.