User manual 09/2009 - Schneider Electric

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User manual 09/2009 - Schneider Electric

The Protection FunctionShort Time ProtectionPresentationShort time protection on Micrologic 5 and 6 trip units is adapted to protecting all types of electricaldistribution application against short-circuit currents.It is identical for Micrologic 5 and 6 trip units.Operating PrincipleShort time protection is definite time:• It incorporates the possibility of an I 2 t inverse time curve function• It can be configured as the Isd pick-up and the tsd trip time delay.Tripping curve:No. Parameter Description1 Ir Long time protection pick-up3 Isd Short time protection pick-up4 tsd Short time protection time delay5 I 2 t Inverse time curve function (ON or OFF)Setting the Short Time Protection (Micrologic 5)The Isd pick-up can be set as follows:• On the Micrologic trip unit, preset by the Isd dial and fine-tuned on the keypad• Via the communication option using the RSU software, preset by the Isd dial on the Micrologic trip unitand fine-tuned via the RSU softwareThe tsd time delay can be set as follows:• On the Micrologic trip unit, set on the keypad• Via the communication option using the RSU softwareThe tsd time delay setting incorporates activation/deactivation of the I 2 t option.Setting the Short Time Protection (Micrologic 6)The Isd pick-up and tsd time delay can be set as follows:• On the Micrologic trip unit, set on the keypad• Via the communication option using the RSU softwareThe tsd time delay setting incorporates activation/deactivation of the I 2 t option.LV434104 09/2009 43

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