Instructions For Digitrip Models 1150 And 1150 Trip Units .

I.L. 70C1036H01If you have any questions or need further information orinstructions, please contact your local representative orthe Customer Support Center at 1-800-356-1234.1.0 GENERAL DESCRIPTION OF DIGITRIP TRIP UNITSThe Digitrip Trip Units are breaker subsystems thatprovide the protective functions of a circuit breaker. Thetrip units are in removable housings, installed in thebreaker, and can be replaced or upgraded in the field bythe end user.This instruction book specifically covers the application ofDigitrip Trip Units, as illustrated in Figure 1.1, installed inMagnum and Magnum DS Breakers. Throughout thisInstructional Leaflet, the use of the term “MagnumBreakers” refers to both the Magnum and Magnum DSlow-voltage, AC power circuit breakers.The Magnum Digitrip line of trip units consists of the 1150for UL standards, and model 1150i for IEC standards.Throughout this Instructional Leaflet, the use of the termDigitrip 1150 trip units refers to both models unlessotherwise stated. There are three possible styles underthe DT 1150 (11LSI, 11LSIG, 11LSIA) and two stylesunder the DT 1150i (11IEC and 11IEC-EF).The Digitrip 1150 trip units may be applied on both 50 and60 Hz systems.Digitrip DT1150 family of trip units have two microprocessors in their design. The partitioning is such that oneprocessor is devoted totally to the task of current protection functions. This processor provides true RMS currentsensing for the proper coordination with the thermalcharacteristics of conductors and equipment. The Digitripanalyzes the secondary current signals from the circuitbreaker current sensors and, when preset current levelsand time delay settings are exceeded, will send aninitiating trip signal to the Trip Actuator of the circuitbreaker. The current sensors provide operating power tothe trip unit. As current begins to flow through the breaker,the sensors generate a secondary current which powersthe trip unit.Page 5mounted in the circuit breaker. The types of protectionavailable for each model are shown in Table 1.1.The Digitrip 1150 family of trip units provides five phaseand two ground (time-current) curve-shaping adjustments. To satisfy the protection needs of any specificinstallation, the exact selection of the available protectionfunction is adjustable. The short delay and ground faultpick-up adjustments can be set for either FLAT or I2tresponse. A pictorial representation of the applicabletime-current curves for the selected protection functions isprovided, for user reference, on the face of the trip unit asshown in Figure 1.1.NOTE: The Digitrip 1150 (11LSI style) and Digitrip 1150i(11IEC) are the two styles that can be used on 3-pole or4-pole circuit breakers for the protection of the neutralcircuit. Only these two styles can provide neutral protection, although all styles can provide neutral metering andalarming (see Figures 3.7, 3.8, and 3.9). Refer to theNational Electric Code (NEC) for the appropriate application for 4-pole breakers.1.2 Mode of Trip and Status InformationOn all DT1150 units, a green light emitting diode (LED),labeled Status, blinks approximately once each second toindicate that the trip unit is operating normally. This StatusLED will blink at a faster rate if the Digitrip is in a pick-up,or overload, mode.Red LEDs on the face of the 1150 family of trip units flashto indicate the cause, or trip mode, for an automatic tripoperation (for example, ground fault, overload, or shortcircuit trip). A battery in the Digitrip unit maintains the tripindication until the Reset button is pushed. The battery issatisfactory if its LED lights green when the Battery Checkbutton is pushed (see Section 6).NOTE: The Digitrip 1150 family provides all protectionfunctions regardless of the status of the battery. Thebattery is only needed to maintain the automatic tripindication.1.3 Installation and RemovalThe second microprocessor provides the display, communications, metering, harmonic calculations, alarming andauxiliary relay functions. These additional features requirethat auxiliary power be provided to the circuit breaker.1.1 ProtectionEach Digitrip DT1150 Trip Unit is completely self-contained and requires no external control power to operateits basic current protection functions. It operates fromcurrent signal levels derived through current sensorsEffective 8/18/991.3.1 Installation of the Trip UnitAlign the Digitrip unit with the molded guide ears on theplatform and spring clips of the Magnum Circuit Breaker.Before plugging into the black edge connector, allign thelong pins on the bottom of the Digitrip into the white, I1,connector. See Figure 1.2. .Press the unit into breakeruntil the PC board edge engages into the connector andthe spring clips engage over the Digitrip’s housing.

I.L. 70C1036H01Page 6Figure 1.2 Installation of the Digitrip Unit into a Magnum Breaker (Side View)1.3.2 Rating Plug InstallationWARNINGDO NOT ENERGIZE THE MAGNUM BREAKER WITHTHE DIGITRIP REMOVED OR DISCONNECTED FROMITS CONNECTOR. DAMAGE TO INTERNAL CURRENTTRANSFORMERS MAY OCCUR DUE TO AN OPENCIRCUIT CONDITION.CAUTIONIF A RATING PLUG IS NOT INSTALLED IN THE TRIPUNIT, THE UNIT WILL INITIATE A TRIP WHEN IT ISENERGIZED.Insert the rating plug into the cavity on the right-handside of the trip unit. Align the three pins on the plug withthe sockets in the cavity. The plug should fit with a slightinsertion force.Effective 8/18/99

I.L. 70C1036H01Page 7To remove the trip unit from the circuit breaker, deflect thetop and bottom spring clips to release the unit from thesteel mounting plate. Pull the unit to disengage the tripunit’s printed circuit board connectors J0 & I1 from thecircuit breaker (see Figure 1.2 and Appendix C).1.4 WiringThe internal components of the breaker and their connection points to the secondary contacts, are shown in thebreaker master connection diagram provided as AppendixC.1.5 Plexiglass CoverA clear, tamper-proof plexiglass door sits on the breakercover. This door, if sealed, allows the settings to beviewed but not changed, except by authorized personnel.The plexiglass cover meets applicable tamper-proofrequirements. The cover is held in place by two coverscrews. Security is insured by the insertion of a standardmeter seal through the holes in both of the cover retentionscrews. The plexiglass cover has an access cutout for theView Functions group of pushbuttons and the Battery Testpushbutton.1.6 DT 1150 Power/Relay ModuleFigure 1.3 Installation of the Rating Plug and MountingScrewCAUTIONDO NOT FORCE THE RATING PLUG INTO THECAVITY.Use a 1/8" (3 mm) wide screwdriver to tighten the M4screw and secure the plug and the trip unit to the circuitbreaker (see Figure 1.3). Close the rating plug door.CAUTIONTHE M4 SCREW SHOULD BE TIGHTENED ONLYUNTIL IT IS SNUG. DO NOT USE A LARGE SCREWDRIVER. A 1/8" (3 mm) WIDE SCREWDRIVER BLADEIS ADEQUATE.1.3.3 Trip Unit/Rating Plug RemovalTo remove the rating plug from the trip unit, open therating plug door. Use a 1/8" (3 mm) wide screwdriver toloosen the M4 screw. Pull the door to aid in releasing therating plug from the unit.Effective 8/18/99The Power/Relay Module (see Figure 1.4) is a standardaccessory for the Digitrip 1150 model. The module isinstalled on the molded platform under the trip unit in theMagnum Circuit Breaker. The module covers the followinginput voltage ratings: 120 VAC, 230 VAC, and 24/48 VDC.The burden of the Power/Relay Module is 10VA.1.6.1 Auxiliary PowerWhen the module is wired and supplied with propervoltage, it will provide an auxiliary power supply so thatthe DT 1150’s (LED) display will be functional even whenthe circuit breaker has no load. A Digitrip 1150 unitwithout auxiliary power will not display any data.1.6.2 Alarm ContactsA second function of this module is to provide either a tripor alarm output contact via the two customer programmed relays within the module. An assortment ofrelay functions can be assigned to these relays. See theAux Relay programming in Appendix D-15 and AppendixF. Each relay is a normally open contact with a programming identification of RELAY A and RELAY C. On thebreaker schematic these are labeled ATR Alarm andATR latch. The ATR latch is a latching relay that will holdcontact status even if Auxiliary

I.L. 70C1036H01Page 81.6.2.3 Block Close RelayAlso in this module is a relay that can block the remoteclosing of a circuit breaker after a trip condition. ThisBlock function is enabled by programming the Aux RelayB. See Appendix D-15.1.7 StandardsThe Digitrip 1150 Trip Units are listed by the UnderwritersLaboratories, Inc. , UL File E52096, for use in MagnumCircuit Breakers. These same units are also listed by theCanadian Standards Association (CSA) under file LR43556.All Digitrip units have also passed the IEC 947-2 testprogram which includes radiated and conducted emissiontesting. As a result, all units carry the CE mark.2.0 GENERAL DESCRIPTION OF MAGNUM CIRCUIT BREAKERS2.1 GeneralMagnum Circuit Breakers are tripped automatically onoverload or fault current conditions by the combinedaction of three components:1. The Sensors, which measure the current levelFigure 1.4 Power/Relay 1150 Trip Unitpower is lost to the breaker. It does require AuxiliaryPower for resetting. The resetting of these relays requiresdepressing the RESET pushbutton on the front panel ofthe Digitrip 1150.1.6.2.2 Ground AlarmA ground fault alarm is one of nine programmable alarmspossible and can provide an early warning of a groundfault condition in process via alarm LED.In additional, an alarm relay can be programmed to beenergized. The alarm relay will reset automatically if theground current is less than the ground alarm pickupsetting.2. The Digitrip Trip Unit, which provides a tripping signalto the Trip Actuator when current and time delaysettings are exceeded3. The low-energy Trip Actuator, which actually trips thecircuit breakerFigure 2.1 shows this tripping circuit for a typical MagnumBreaker. This arrangement provides a very flexiblesystem, covering a wide range of tripping characteristicsdescribed by the time-current curves referenced inSection 9.2.The automatic overload and short circuit tripping characteristics for a specific circuit breaker are determined bythe ratings of the installed current sensors with a matching rating plug and the selected functional protectionsettings. Specific setting instructions are provided inSection 4.On the LSIA style unit, a red ALARM ONLY LED (seeFigure 3.3) will indicate the presence of ground faultcurrent, when is in excess of GROUND PICKUP setting.Ground tripping will not occur with the LSIA style unit.Effective 8/18/99

I.L. 70C1036H01Page 9When the functional protection settings are exceeded, theDigitrip unit supplies a trip signal to the Trip Actuator. As aresult, all tripping operations initiated by the protectionfunctions of the Digitrip Trip Unit are performed by itsinternal circuitry. There is no mechanical or direct magnetic action between the primary current and the mechanical tripping parts of the breaker, thus externalcontrol power is not required for overload or fault currenttripping.WARNINGIMPROPER POLARITY CONNECTIONS ON THE TRIPACTUATOR COIL WILL DEFEAT THE OVERLOADAND SHORT CIRCUIT PROTECTION, WHICH COULDRESULT IN PERSONAL INJURY.located under the black molded platform on which theDigitrip unit is supported. The Trip Actuator contains apermanent magnet assembly, moving and stationary coreassemblies, a spring and a coil. Nominal coil resistance is25 ohms and the black lead is positive. The circuitbreaker mechanism assembly contains a mechanismactuated reset lever and a trip lever to actuate the trippingaction of the circuit breaker.When the Trip Actuator is reset by the operating mechanism, the moving core assembly is held in readinessagainst the force of the compressed spring by the permanent magnet. When a tripping action is initiated, the lowenergy Trip Actuator coil receives a tripping pulse fromthe Digitrip unit. This pulse overcomes the holding effectof the permanent magnet, and the moving core is released to trigger the tripping operation via the trip lever.2.3 Ground Fault ProtectionOBSERVE POLARITY MARKINGS ON THE TRIPACTUATOR LEADS AND CONNECT THEM PROPERLYUSING THE INSTRUCTIONS PROVIDED.Only the Digitrip 1150 cat# 11LSIG and Digitrip 1150i cat#11IEC-EF provide ground fault protection.2.2 Low-Energy Trip Actuator2.3.1 GeneralThe mechanical force required to initiate the trippingaction of a Magnum Circuit Breaker is provided by aspecial low-energy Trip Actuator. The Trip Actuator isWhen the Digitrip 1150 family includes ground faultprotection features, the distribution system characteristics(for example, system grounding, number of sources,number and location of ground points, and the like) mustFigure 2.1 Tripping Circuit for a Typical Magnum Breaker (Partial)Effective 8/18/99

I.L. 70C1036H01Page 10be considered along with the manner and location inwhich the circuit breaker is applied to the system. Theseelements are discussed in Sections 2.3.3 through 2.3.6.TESTS TO COMPLY WITH NEC REQUIREMENTSUNDER ARTICLE 230-95(C).2.3.3 Source Ground SensingThe Digitrip 1150 family uses three modes of sensing todetect ground fault currents: residual, source ground, andzero sequence (see Table 2.1). Magnum Circuit Breakerscan accommodate all three types except for 4-polebreakers. The breaker secondary contact inputs B-6 andB-7 are used to configure the breaker cell positions for thethree schemes. A jumper from B-6 to B-7 programs thetrip unit for either a source ground or zero sequenceconfiguration. Removing the jumper will program the unitfor a residual ground fault scheme. This jumper resideson the stationary side of the switchgear assembly. In allthree schemes, the proper current sensor input is required on the external sensor input terminals B-4, B-5 ofthe breaker secondary contacts.Table 2.1 Digitrip Sensing ModesGround (Earth)FaultSensing MethodBreakerSecondaryContacts Req’dResidualNo Jumper3 or 4 pole2.2, 2.3, 2.5, 2.9Digitrip GFSensingElementUsedelement R5Source GroundJumper B6 to B73 pole only2.7element R4Zero SequenceJumper B6 to B73 pole only2.8element R4ApplicableBreakersFigureReferenceDepending upon the installation requirements, alternateground fault sensing schemes may be dictated (seeFigures 2.6 and 2.7). The ground return method is usuallyapplied when ground fault protection is desired only onthe main circuit breaker in a simple radial system. Thismethod is also applicable to double-ended systems wherea midpoint grounding electrode is employed. For thismode of sensing, a single current sensor mounted on theequipment-bonding jumper directly measures the totalground current flowing in the grounding electrodeconductor and all other equipment-grounding conductors.In the CURRENT (protection) submenu, there is a setting(EXT GND CT RATIO) that enable the proper scaling ofground pickup and display of ground current if ExternalGround CT is employed. This screen is presented whenjumper B-6 to B-7 is presented on a trip unit equiped withGROUND. External Ground CT ratios of 10, 100, 200,400, 800, 1000 A:1 and “none” setting are selectable, with“none” defaulting to the plug In rating. With the correctratio selected the GF pickup settings are adjustable inAMPERES.Note: This information applies to Trip Units with Ground2.3.2 Residual Sensing2.3.4 Zero Sequence SensingResidual Sensing is the standard mode of ground faultsensing in Magnum Circuit Breakers. This mode utilizesone current sensor on each phase conductor and one onthe neutral for a 4-wire system (shown in Figures 2.2and 2.3). If the system neutral is grounded, and no phaseto neutral loads are used, the Digitrip 1150 with groundincludes all of the components necessary for ground faultprotection. This mode of sensing vectorially sums theoutputs of the three or four individual current sensors. Forseparately-mounted neutrals, as long as the vectorial sumis zero, then no ground fault exists. The neutral sensormust have characteristics and a ratio which matches thethree internally-mounted phase current sensors. Availabletypes of neutral sensors are shown in Figure 2.4. Residual ground fault sensing features are adaptable tomain and feeder breaker applications.Zero Sequence Sensing, also referred to as vectorialsummation (see Figure 2.8), is applicable to mains,feeders, and special schemes involving zone protection.Zero Sequence current transformers (4 1/2“ x 13 1/2“ [114mm x 342 mm] rectangular inside dimensions) areavailable with 100:1 and 1000:1 ratios. The EXT GND CTRATIO setting described above is applicable for zerosequence.2.3.5 Multiple Source/Multiple GroundA Multiple Source/Multiple Ground scheme is shown inFigure 2.9. In this figure, a ground fault is shown whichhas two possible return paths, via the neutral, back to itssource. The three neutral sensors are interconnected tosense and detect both ground fault and neutral currents.Call Cutler-Hammer for more details on this scheme.CAUTION2.3.6 Ground Fault SettingsIF THE SENSOR CONNECTIONS ARE INCORRECT, ANUISANCE TRIP MAY OCCUR. ALWAYS OBSERVETHE POLARITY MARKINGS ON THE INSTALLATIONDRAWINGS. TO INSURE CORRECT GROUND FAULTEQUIPMENT PERFORMANCE, CONDUCT FIELDThe adjustment of the ground fault functional settings(FLAT response or I2t) is discussed in Section 4.2.1.8.The effect of these settings is illustrated in the groundfault time-current curve referenced in Section 9.Effective 8/18/99

I.L. 70C1036H01Page 112.4 Current Sensors (Magnum Frames less than or equal to3200A)The three (3-pole) or four (4-pole) primary current sensors are installed internally in the circuit breaker on thelower conductors of the breaker. The current sensorrating defines the breaker rating (In). For example,2000A:1A sensors are used on a 2000A rated breaker.There are four auxiliary current transformers with a ratioof 10:1 which further step down the rated current to100 milliamperes, which is equivalent to 100% (In)

Magnum and Magnum DS Breakers. Throughout this Instructional Leaflet, the use of the term “Magnum Breakers” refers to both the Magnum and Magnum DS low-voltage, AC power circuit breakers. The Magnum Digitrip line of trip units