Eaton Magnum DS Technical Data Manual

Also see for Magnum DS: Instruction leaflet Instruction booklet Instructions Instructional Leaflet

Technical Data Effective: May 1998Page 14TD.44A.01.T.ECutler-HammerMagnum DSMetal-EnclosedLow-Voltage SwitchgearGroup Motor Feeder BreakersTypical loads for such circuits aremotor control centers. The feederbreakers may be either manually orelectrically operated as preferred, andare usually equipped with long andshort delay trip protection only forcoordination with the individual motorcircuit devices. The minimum longdelay pickup setting should be 115% ofthe running current of the largestmotor in the group, plus the sum of therunning circuits of all other motors.Motor Starting Feeder BreakersThese breakers are usually electricallyoperated, with long delay and instanta-neous tripping characteristics formotor running, locked rotor and faultprotection. The breaker sensor ratingshould be chosen so that the longdelay pickup can be set at 125% ofmotor full load current for motors witha 1.15 service factor, or at 115% for allother motors. Contactors are recom-mended for this application when thereare a number of daily operationsinvolved.When system short circuits are less than40 times the motor full load current, themotor breaker tripping characteristicshould include a short delay characteris-tic for greater fault protection.ApplicationFeeder Breakers – GeneralCircuit breakers for feeder circuit pro-tection may be manually or electricallyoperated, with long and short delay orlong delay and instantaneous type tripdevices, and trip settings, as requiredfor the specific circuit and load require-ments.Feeder breakers as selected in TablesA1 through A4 have adequate inter-rupting ratings, and are assumed tohave adequate continuous current rat-ings for maximum load demands.General purpose feeder breakers, suchas for lighting circuits, are usuallyequipped with long delay and instanta-neous trip devices, with the long delaypickup set for the maximum loaddemand in the circuit. Where arcingfault protection is required, the instan-taneous trip setting should be as lowas practicable consistent with inrushrequirements.www . ElectricalPartManuals . com