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Entry type: FAQ, Entry ID: 21655969, Entry date: 05/30/2005
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3VF3 to 3VF8: Tolerances of the overcurrent release in compliance with IEC 947-2

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QUESTION:
3VF3 to 3VF8: Tolerances of the overcurrent release in compliance with IEC 947-2

ANSWER:
The tolerances of the short-circuit release are + - 20 according to § 7.2.1.2.4. Test currents with corresponding release times are defined for the overload release. The pairs of values are different, depending on whether a device or motor protection or circuit-breakers are meant. Attached you will find both tables (Switching, Protection, and Distribution in Low-Voltage Networks Manual page143, Publicis publisher, order no. A19100-L531-B671(page and order no. refer to German Version)). The tolerances of the release time of the overload releases of the circuit-breakers for the motor protection are between triple and sixfold the current setting + - 20 %.
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