| US 7,521,916 B2 | ||
| Apparatus for the detection of a current and method for operating such an apparatus | ||
| Bernhard Deck, Weilheim (Germany); Bruno Sabbattini, Zürich (Switzerland); and Richard Bloch, Nussbaumen (Switzerland) | ||
| Assigned to ABB Research Ltd, Zurich (Switzerland) | ||
| Filed on Dec. 19, 2007, as Appl. No. 12/3,042. | ||
| Application 12/003042 is a continuation of application No. PCT/CH2005/000357, filed on Jun. 29, 2005. | ||
| Prior Publication US 2008/0136403 A1, Jun. 12, 2008 | ||
| Int. Cl. G01R 1/10 (2006.01) | ||
| U.S. Cl. 324—110 | 38 Claims |
| 1. 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.
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