| 摘要 |
A blocking oscillator power pack is based on a conventional design in which the transformer supplied by way of a rectified line alternating voltage is provided with a first secondary winding which supplies an electrical device, as a load, by way of a further rectifier and with a secondary winding which serves for the supply of a control circuit. As a final control element, the control circuit contains a switching transistor by way of which the current in the primary winding of the transformer is adjusted. It has been shown, however, that an undesired rise of the secondary current is also possible due to a failure of the control circuit. In order to suppress such rise, a protective circuit is provided which remains inactive given intact operation of a control circuit. When, however, the current in the secondary circuit transgresses a prescribed maximum value, the protective circuit is initiated and inhibits the primary current flowing via the switching transistor until the malfunction in the control loop has been dismantled. In particular, the protective circuit has an inhibiting effect on the output of the control circuit.
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