Eaton SBN-508 Instructions For Installation, Operation And Maintenance

Also see for Magnum SB Series: Technical product guide

Contents

26Instructions for Installation, OperatiMaintenance of Magnum SB InsulatedLow V oltage Power Circuit BreakeEATON CORPORATION www.eaton.comInstructional Leaflet IB2C12063H03Effective March 2012Rating PlugAll Magnum SB circuit breaker trip units use a fixed typerating plug The current rating of the rating plug must matchthe current rating of the integrally mounted current sensors(Figures 6 and 34 and Table 6) The rating plug performsseveral functions:1 It tells the trip unit what the rating is of the current sensorsA label on the front of the rating plug clearly indicates thatthe rating plug and sensors must have the same rating2 It determines the maximum instantaneous setting which isa function of the current sensor rating3 The National Electrical Code (NEC) requires that themaximum ground fault pickup value not exceed 1200amperes A properly matched rating plug accomplishes thisrequirement for higher ampere sensors by incorporatingcircuitry to identify that level by sensor ratingIf the rating plug is removed from the trip unit, the circuitbreaker will trip if it is carrying current Make certain the ratingplug is secured in position with its retaining screw Do nottorque the retaining screw beyond 15 In-OzRefer to Table 6 for a tabulation of the available rating plugsCurrent SensorsThree toroidally wound current sensors are installed at therear of the circuit breaker on the lower terminals (Figure 36)The sensors produce an output current proportional to the loadcurrent Under preselected conditions of current magnitudeand time, the sensors furnish the trip unit with a signal and theenergy required to trip the circuit breakerNeutral current sensors are available for customer installationThe additional sensor is not supplied with the circuit breakerand must be ordered separately They are wired to the trip unitthrough the secondary contacts of the circuit breakerRefer to Table 6 for a tabulation of the available current sensorratingsTestReceptacleRating PlugPop Out TripFlagAuxiliary PowerModule PortFigure 34. Digitrip RMS 1150 Programmable Trip Unit Installed inMagnum SB Circuit BreakerFigure 35. Hand Held Tester