| 摘要 |
The invention concerns a protective device against fault currents which, with a triggering arrangement, performs at least the functions of detecting a fault current and or triggering power-down of the network to be protected. The triggering arrangement is adjusted so as to maintain the triggering fault current, particularly in case of fault current frequency, in the triggering arrangement, outside the most strict quartic curve (A), corresponding to the protection of persons in case of indirect contact, below the triggering quartic curve (B), corresponding to protection against fire, the triggering quartic curve (B) satisfying the relationship: IGrenz(f)/I DELTA n=F(f)=B=const., wherein IGrenz(f)=WBrand/UNetz. In said relationships, IGrenz(f) represents the limit fault current permissible for the corresponding frequency, where there is still no risk of fire; I DELTA n represents the nominal triggering fault current at the frequency of the network taking into consideration the protection of persons; WBrand represents the power limit in watt required for protection against fire; UNetz represents the network voltage to be protected and F(f) represents what is called the frequency factor.
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