A circuit breaker device for protecting a low-voltage electric circuit includes a mechanical break contact unit connected in series with an electronic interruption unit. The break contact unit is switchable by opening contacts to prevent current flow or by closing the contacts to allow current flow in the low-voltage circuit. The electronic interruption unit is switchable by semiconductor-based switching elements into a high-resistance state of the switching elements to prevent current flow or into a low-resistance state of the switching elements to allow current flow in the low-voltage circuit. The amplitude of the current in the low-voltage circuit is ascertained to provide instantaneous current values which are compared with at least one current threshold value, and if the threshold value is exceeded, prevention of current flowing in the low-voltage circuit is initiated. The at least one current threshold value is adjusted according to a temperature level of the circuit breaker device.

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