User manual 09/2009 - Schneider Electric

The Protection FunctionIsd Pick-Up Setting ValueThe Isd pick-up setting value is expressed in multiples of Ir.The default Isd pick-up setting value is 1.5 Ir (minimum dial value).The table below shows the setting values (preset by a dial) and setting ranges (set on the keypad) of theIsd pick-up:Type of SettingPreset by a dial(Micrologic 5)Setting range on the keypad (1)Step: 0.5 IrThe accuracy range is +/- 10%.Value or Setting Range (xIr)1.5 2 3 4 5 6 7 8 101.5 1.5/2 1.5...3 1.5...4 1.5...5 1.5...6 1.5...7 1.5...8 1.5...10(1) For Micrologic 6 trip units, the setting range value on the keypad is: 1.5...10 Ir.tsd Time Delay Setting ValueThe table below indicates the setting values for the tsd time delay with the I 2 t OFF/ON option expressedin second(s) and the associated non-tripping and breaking times expressed in milliseconds (ms):ParameterValuetsd with I 2 t OFF (s) 0 0.1 0.2 0.3 0.4tsd with I 2 t ON (s) — 0.1 0.2 0.3 0.4Non-tripping time (ms) 20 80 140 230 350Maximum breaking time (ms) 80 140 200 320 500The default tsd time delay setting value is 0 s with I 2 t OFF.I 2 t ON/OFF FunctionThe I 2 t inverse time curve function is used to improve circuit breaker discrimination. It is particularlynecessary when a protection device using inverse time only, for example a fuse protection device, isinstalled downstream.Example:The figures below illustrate an example of discrimination between a Compact NSX630 upstream, and agG-250 A fuse downstream (calculation performed by the Ecodial software):I 2 t OFFt(s)I 2 t ONt(s)NS800N - Micrologic 5.0 A - 800 ANS800N - Micrologic 5.0 A - 800 AgG - 250 AgG - 250 AI (A)I (A)Total discrimination between the protections is provided by using the I 2 t ON function on the short timeprotection.44 LV434104 09/2009