| 摘要 |
PCT No. PCT/DE90/00272 Sec. 371 Date Sep. 20, 1991 Sec. 102(e) Date Sep. 20, 1991 PCT Filed Apr. 6, 1990 PCT Pub. No. WO90/12439 PCT Pub. Date Oct. 18, 1990.The invention concerns a device for a.c. cut-in limitation of a power-supply unit with inductive reactance. The device has a series-connected first a.c. switch and a phase-angle control circuit by means of which a time lag can be introduced in the connection between the primary winding and the mains a.c. voltage at the point in time that cut-in takes place. The control electrode of the first a.c. switch of the floating phase-angle control circuit is connected to the output of a control circuit by means of which a trigger voltage, which is synchronized with the mains a.c. voltage, is generated, when the power-supply unit is switched in, at a selectable phase angle between 90 and 0 degrees before a zero passage of the main a.c. voltage. The trigger voltage can be suppressed before the zero passage of the mains a.c. voltage is reached in order to switch off the power-supply unit. A capacitor connected in parallel with the power-supply unit enables the residual magnetism to be set before or after each switching in or out of the unit so that the power-supply unit can always and under any condition be switched in without the peak cut-in exceeding the load current.
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