| 摘要 |
The invention relates to an electronic ballast for operating a discharge lamp LA, in which a pump circuit D6, C8, C9, L1 charges an intermediate circuit capacitor C6 from the AC voltage of a converter V1, V2. A voltage limitation circuit R8, R3, D5, R4, R5, C3, SD is connected in parallel with the intermediate circuit capacitor C6. A dissipation element R8 in the voltage limitation circuit R8, R3, D5, R4, R5, C3, SD converts electrical energy into thermal energy when a maximum value for the voltage across the intermediate circuit capacitor C6 is exceeded. The current through the measuring resistor R3 is measured as the voltage UC3 across said measuring resistor R3, is detected in a delay circuit R4, R5, C3 and is used to control a shutdown device SD for the converter V1, V2.
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