Method and apparatus for avoiding power-up current surge

Abstract

A method and apparatus for avoidance of power-up current surge upon activation of a current supply device under inductive effect. An alternating-current switch is connected in series with the current supply device and a phase cut-in circuit is provided for enabling adjustable connection of the current supply device with the mains alternating voltage starting with the instant of powering up with equal-size unipolar phase segments. A switching unit is provided for activation of the phase cut-in circuit so that a predetermined number of the equal-size unipolar segments can be produced. An oppositely poled half wave which follows in time immediately is switched with an ignition signal of 170 to 180 degrees. In the phase cut-in circuit, respectively, an ignition signal is produced at the predetermined phase cut-in angle in the half waves following this half wave. Accordingly, independently of the remanence of the current supply device, as determined by a preceding deactivation, it is safely ensured in a simple manner with a small number of electronic components, for example, that a brightening of dimmed low-voltage illuminating systems is effected or that a welding transformer is switched on without the occurrence of a power-up peak current.

Dependencies are inferred from the claim text.