Patent ID: 7521916

Claim:
Apparatus for the detection of a primary current in a protection current range with a current sensor, the protection current range having an upper protection current limit, and the apparatus comprising a current sensor which generates a voltage signal, the same current sensor is suitable for measuring current in a metering current range with an upper metering current limit, wherein the apparatus further comprises a passive, analog attenuation element and a voltage-limited electronic element, which has an upper electronic element protection voltage limit and an upper electronic element metering voltage limit, the electronic element metering voltage limit being smaller than the upper electronic element protection voltage limit and which electronic element is suitable to measure a secondary protection voltage signal with measuring precision within a protection voltage range having an upper protection voltage limit, the protection voltage signal being generated from a primary protection current, and which is suitable to measure a metering voltage signal within a metering voltage range with an upper metering voltage limit, the metering voltage signal being generated from a metering current, and the metering voltage limit being smaller than the protection voltage limit, the same electronic element being suitable to measure a protection and metering voltage signal and wherein for a voltage signal in the protection voltage range, which signal exceeds the upper electronic element protection voltage limit, an electrical connection from the current sensor to the passive, analog attenuation element is present, the attenuation element attenuating the protection and metering voltage signals by an attenuation factor, the attenuation factor being larger than unity and the protection voltage signal divided by the attenuation factor being smaller than or equal to the upper electronic element protection voltage limit, or for a voltage signal in the metering voltage range, which signal exceeds the upper electronic element metering voltage limit, an electrical connection from the current sensor to the passive, analog attenuation element to the current sensor is present, the attenuation element attenuating the protection and metering voltage signals by an attenuation factor, the attenuation factor being larger than unity and the metering voltage signal divided by the attenuation factor being smaller than or equal to the upper electronic element metering voltage limit.