User manual 09/2009 - Schneider Electric

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User manual 09/2009 - Schneider Electric

The Protection FunctionProtection for Motor-FeedersPresentationMicrologic 6 E-M trip units on Compact NSX circuit breakers:• Provide protection for direct-on-line motor-feeders (direct-on-line starting is the most widely used typeof motor-feeder)• Integrate the basic protections (overload, short-circuit and phase unbalance) for the motor-feeder andadditional protections and/or specific options for motor applications• Allow protection and coordination of the motor-feeder components that comply with the requirementsof standard IEC 60947-2 and IEC 60947-4-1 (see the Compact NSX circuit breakers - User manual).DescriptionCompact NSX circuit breakers equipped with the Micrologic 6 E-M trip unit can be used to create motorfeedersto 2 devices.1A11B1C 321 Compact NSX circuit breaker equipped with a Micrologic 6 E-M trip unit1A Short-circuit protection1B Overload protection1C Ground fault current protection2 Contactor3 SDTAM Module OptionOperating StatesThe Micrologic 6 E-M trip unit considers the application to be operating as soon as the 10% of Ir pick-upis crossed in a positive direction by the motor current.2 operating states are considered:• Startup• Steady stateStartupThe Micrologic 6 E-M trip unit considers the application to be in startup mode according to the followingcriteria:• Start: As soon as the 10% of Ir pick-up is crossed in a positive direction by the motor current• End: As soon as the Id pick-up is crossed in a negative direction or at maximum after a td time delaydefined as follows:• If long time protection has not been activated (default scenario), the Id pick-up equals 1.5 Ir and thetd time delay equals 10 s (non-configurable values).Exceeding the 10 s time delay does not result in tripping.• If long time protection (see Long Start Motor Protection, page 71) has been activated, the Id pickupequals Ilong and the td time delay equals tlong (configurable values).Exceeding the tlong time delay results in long time protection tripping.NOTE: The Micrologic trip unit measurement electronics filters the subtransient state (first current peakof approximately 20 ms on contactor closing). This current peak is not therefore taken into account whenassessing whether the Id pick-up has been crossed.LV434104 09/2009 55

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