Eaton Digitrip 520V User manual

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Page 1
I.L. 66A7534H04
1.0 GeneralDescriptionofDigitripTripUnits ................. 2
1.1 Protection ............................................................... 3
1.2 ModeofTripandStatusInformation ........................ 3
1.3 InstallationandRemoval.......................................... 3
1.3.1 InstallationoftheTripUnit............................ 3
1.3.2 Installationofthe Rating Plug....................... 3
1.3.3 TripUnit/Rating Plug Removal...................... 4
1.4 InstallingtheCHType-VCurentSensors................. 5
1.4.1 Installation of the Rating Plug...................... 5
1.4.2 CH Type-V Current Sensor Functiionality .... 5
1.5 PlexiglassCover ..................................................... 5
1.6 GroundAlarm/PowerSupply Module (520MCV)....... 5
1.6.1 Auxilary Power ............................................ 7
1.6.2 GroundAlarm .............................................. 7
1.6.3 Ground Fault Trip ........................................ 7
1.6.4 Ground FaultAlarm ..................................... 7
1.7 DisplayFeature(520MCV) ...................................... 7
1.8 UL,CSAandCERecognition.................................. 8
2.0 GeneralDescriptionof VCP-T,VCP-TR
andT-VAC,T-VACRCircuit Breakers....................... 8
2.1 General ................................................................... 8
2.2 LowEnergyTripActuator ........................................ 9
2.3 GroundFaultProtection .......................................... 9
2.3.1 General ........................................................ 9
2.3.2 Zero SequenceSensing ............................... 9
2.3.3 ResidualSensing......................................... 9
2.3.4 GroundFaultSettings................................ 10
3.0 PrinciplesofOperation .......................................... 12
3.1 General ................................................................. 12
3.2 TripandOperationIndicators................................. 12
3.3 ZoneInterlocking ............................................. 12, 28
4.0 Protection Settings ............................................... 14
4.1 General ................................................................. 14
4.2 LongDelayCurrentSetting ................................... 14
4.3 LongDelayTimeSetting ....................................... 14
4.4 ShortDelayCurrentSetting................................... 15
4.5 ShortDelay TimeSetting ...................................... 15
4.6 InstantaneousCurrentSetting ............................... 15
4.7 GroundFaultCurrentSetting................................. 16
4.8 GroundFaultTimeDelaySetting .......................... 16
4.9 INCOM(520MCV).................................................. 16
4.9.1 Breaker InterfaceModule (BIM) .................. 16
4.9.2 Remote MasterComputer .......................... 16
4.9.3 INCOM NetworkInterconnections .............. 17
5.0 TestProcedures .................................................... 18
5.1 TestPrecautions ................................................... 18
5.2 When to Test ........................................................ 18
5.3 FunctionalFieldTesting ........................................ 18
5.3.1 Field Test Kit............................................... 18
5.3.2 Handheld Functional Test Kit...................... 19
5.3.2.1 Description of HandheldTest Kit...... 19
5.3.2.2 Test Procedure................................ 19
5.3.2.3 Currents .......................................... 19
5.3.2.4 Batteries ......................................... 19
5.4 PerformanceTesting of DigitripTripUnits .............. 19
5.4.1 General ...................................................... 19
5.4.2 Testing using MS-2 MultiAMP®Tester....... 19
5.4.2.1 Description of MS-2 Tester .............. 19
5.4.2.2 Primary Injection Testing ................. 20
5.4.2.3 Secondary InjectionTesting............. 21
6.0 Battery ................................................................. 23
6.1 General ................................................................. 23
6.2 Battery Check ....................................................... 23
6.3 Battery Installation and Removal ........................... 23
7.0 FrameRatings
(SensorRatingsandRatingPlugs)....................... 24
8.0 RecordKeeping .................................................... 24
9.0 References............................................................ 24
9.1 MediumVoltageTypeVCPCircuit Breakers.......... 24
9.2 Time-CurrentCurves .............................................. 24
AppendixA Zone Interlocking Examples..................... 28
AppendixB TroubleshootingGuide ............................ 30
Appendix C Typical Breaker Master
Connection Diagram................................ 32
Appendix D MODBUS Translator Wiring .................... 33
Manufacturer’sStatement ............................................. 34
I.L. 66A7534H04
Instructions for Digitrip Models 520V and 520MCV
for use only in Cutler-Hammer Type VCP-T, VCP-TR
and T-VAC, T-VACR Circuit Breakers
Table of Contents

Effective 8/2006
Page 2 I.L. 66A7534H04
WARNING
DO NOTATTEMPT TO INSTALL OR PERFORM
MAINTENANCE ON EQUIPMENT WHILE IT IS
ENERGIZED.DEATH ORSEVERE PERSONALINJURY
CANRESULTFROMCONTACT WITHENERGIZED
EQUIPMENT. ALWAYS VERIFY THAT NO VOLTAGE IS
PRESENTBEFORE PROCEEDING.ALWAYSFOLLOW
SAFETYPROCEDURES. CUTLER-HAMMERIS NOT
LIABLE FOR THE MISAPPLICATION OR
MISINSTALLATION OF ITS PRODUCTS.
WARNING
OBSERVEALLRECOMMENDATIONS,NOTES, CAU-
TIONS,AND WARNINGS RELATING TO THE SAFETY
OFPERSONNELANDEQUIPMENT.OBSERVEAND
COMPLYWITHALLGENERALAND LOCAL HEALTH
ANDSAFETY LAWS,CODES,ANDPROCEDURES.
NOTE:The recommendations andinformationcontained
hereinarebasedonexperienceandjudgement,but should
notbeconsidered to be all inclusive ortocover every
application or circumstance which may arise.
NOTE: Ifyouhave any questions or need additional
informationorinstructionsconcerningtheoperationor
installation of this device, please contact your local
representativeorthe Cutler Hammer Customer Support
Center.
1.0 GENERAL DESCRIPTION OF DIGITRIP TRIP UNITS
TheDigitripTrip Unit is a breakersubsystemthat provides
theprotective functions for a circuitbreaker.The trip units
areinremovable housings, installed in thecircuitbreaker,
andcan be replacedor upgraded inthe field by the
customer.
Thisinstruction book specifically covers the applicationof
the Digitrip Trip Units (See Figure 1.1) installed in Type
VCP-T, VCP-TR,T-VACorT-VACRMediumVoltage
CircuitBreakers.
Figure 1.1 Digitrip Trip Unit with Rating Plug
TheDigitrip 520V and 520MCV trip unitsmay be applied
on both 50 and 60 Hertz systems. It detects the power and
frequency and adjusts itself automatically.
TheDigitrip520Vand520MCVareselfpoweredandself
protecting trip units designed to function only with the
associatedCHType-Vcurrentsensors.

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CAUTION
CONNECTINGTHISTRIP UNIT TO CURRENT SEN-
SORSOTHERTHAN CH TYPE-V MIGHT DAMAGEOR
DESTROYIT.
Alltripunit models are microprocessor-basedACprotec-
tiondevicesthatprovide true RMS current sensing for the
propercoordinationwiththe thermal characteristics of
conductorsandequipment.The primary function of this
Digitrip trip unit is circuit protection. The Digitrip analyzes
thesecondarycurrent signals from the CH Type-Vcurrent
sensorsand,when preset current levels andtimedelay
settings are exceeded, will send an initiating trip signal to
the TripActuator of the circuit breaker, causing it to “open.”
In addition to the basic protection function, the Digitrip
520Vand520MCVprovidemodes of trip indication such
as: •LongTimetrip(overload)
•ShortTimetrip
•Instantaneoustrip
•Ground(Earth)Faulttrip
TheCHType-Vcurrentsensorsprovidethepowertothe
trip unit.As current begins to flow through the breaker, the
sensorsgenerateasecondary current which powers the
trip unit. No auxilary power is needed to trip the circuit
breaker.
TheDigitrip520Vand520MCVtripunitshavefivephase
andtwoground(time-current)curve shaping adjustments.
To satisfy the protection needs of any specific installation,
theexactselection of the available protection function
adjustments is necessary. The short delay and ground
fault pick-up adjustments can be set for either FLAT or I2t
response.Apictorial representation of the applicable time-
currentcurvesfor the selected protection functionsis
provided,foruser reference, on the face ofthetrip unit as
shown in Figure 1.1. The user chooses the settings
according to the needs of his application. (See Sections
4.0 & 9.2)
1.1 Protection
TheDigitrip trip system; including associated CH Type-V
currentsensors,require no external control power to
operatetheirprotection systems. They operate from
currentsignallevelsderived through the CH Type-Vcurrent
sensors.
Status LED will also blink at a faster rate if the Digitrip is
ina“LongPick-up” (overload) mode.
Four red LEDs on the face of the trip units flash to indicate
the cause of trip for an automatic trip operation... i.e.:
LongDelay(overload),Short Delay,Instantaneousor
Ground(Earth) Fault.Abattery, inside the rating plug
compartment of the Digitrip unit, maintains the trip indica-
tion until the Reset/Battery Test button is pushed. The
battery is satisfactory if its Battery Check LED lights
green when the Battery Check button is pushed (See
Section 6).
NOTE: TheDigitripunitprovidesallprotectionfunctions
independant of the status of the battery. The battery is
used only to maintain the automatic trip indication.
1.3 Installation and Removal
1.3.1 Installation of the Trip Unit
Align the Digitrip unit with the guide pins and spring clip of
the circuit breaker. Press the unit into the breaker until the
pins on the trip unit seat firmly into the connector housing
and the unit clicks into place (see Figure 1.2).
1.3.2 Installation of the Rating Plug
Insert the rating plug into the cavity on the right-hand side
of the trip unit. Carefully align the three pins on the plug
with the sockets in the cavity. The plug should fit with a
slightinsertionforce.
WARNING
DONOT CLOSE THECIRCUITBREAKER WHEN THE
DIGITRIPIS REMOVED OR DISCONNECTED.DAMAGE
TOASSOCIATEDCURRENTTRANSFORMERS MAY
OCCURDUE TO AN OPEN CIRCUITCONDITION.
THERE IS NO PROTECTION FOR THE LOAD CIRCUIT.
CAUTION
IF ARATING PLUG IS NOT INSTALLED IN THE TRIP
UNIT, THE UNIT WILL INITIATE A TRIP WHEN IT IS
ENERGIZED.INADDITIONTHEINSTANTANEOUS LED
OF THE DIGITRIP TRIP UNIT WILL LIGHT DUE TO A
MISSING OR BAD RATING PLUG.
1.2 Mode of Trip and Status Information
A green light emitting diode (LED), labeled Unit Status in
Figure 1.1, blinks approximately once each second to
indicate that the trip unit is operating normally. This Unit

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Figure 1.2 Installation of the Digitrip Unit into Breaker (Side View)
Mounting Boss
Steel Mounting Plate
Guide / Rejection Pin
Dimple
Pin 1
Connector K2
M-4 x 80mm
Mounting Screw
Pin 1 - Connector K1
Rating Plug
(3 Pins)
0.045 Dia. Pins Exiting
Digitrip Housing
Spring Clip
Wires with
Connectors
Digitrip 520V / 520MCV
0.045 Dia. Pins Exiting
Digitrip Housing
Trip
Actuator
Connector I1
J3 (3 point)
J4 (4 point)
Connectors
GroundAlarm/Power
Supply Module
(520MCV option only)
Figure 1.3 Installating the Rating Plug & Mounting Screw
CAUTION
DO NOT FORCE THE RATING PLUG INTO THE CAVITY.
USE A 1/8" (3MM) WIDE SCREWDRIVER TO TIGHTEN
THEM4SCREW AND SECURE THE PLUGAND THE
TRIP UNIT TO THE CIRCUIT BREAKER (See Figure 1.3).
CLOSETHERATINGPLUG DOOR.
CAUTION
THEM4SCREW SHOULD BE TIGHTENED ONLYUNTIL
IT IS SNUG BECAUSE THERE IS NO STOP. DO NOT
USE A LARGE SCREWDRIVER. A 1/8" (3mm) WIDE
SCREWDRIVERBLADE ISADEQUATE.
1.3.3 Trip Unit/Rating Plug Removal
To remove the rating plug from the trip unit, make sure the
circuit breaker is open. Now open the left side of the rating
plugdoor.Use a 1/8" (3mm) widescrewdrivertoloosen and
removetheM4x80mm mounting screw.Pull the rating plug
from the trip unit.
To remove the trip unit from thecircuitbreaker,remove the
breakercoverscrewsusinga10mmdriver.Deflect the
spring clip under the trip unit to release the unit from the
steel mounting plate. Pull the unit straight forward to
disengagethetwo 9-pin connectors from the circuitbreaker
control circuit. (See Figure 1.2).

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1.4 Installing the CH Type-V Current Sensors
Theinternalcomponentsofthecircuitbreaker,andhow
they are wired out to the breaker secondary contacts are
shown in Figures 1.4, 1.5, 1.6 and 2.3.Also refer to the
masterconnectiondiagramprovidedinAppendixC.
1.4.1 Installation Procedure
TheCHType-VCurrentSensors/RatingPlugKitsupplied
with this breaker must be installed and wired by the user.
The installation steps are as follows:
a. PRIMARY- Mount one CH Type-V current sensor on the
insulatedbushingbehindthecircuit breaker. The bushing
must be rated for the system Lightning Impulse Withstand
Voltage (LIWV), and the ground (earth) shield terminalor
ground(earth) shield surface must be connectedto the
ground(earth)bus. Confirm that the polarity mark (reddot)
on the front of the current sensor faces the circuit breaker.
b.SECONDARY- Connect secondary terminals ofthe
current sensor to the correct terminals in the switchgear
control circuit using #14AWGType SIS wire. Terminal X1
is the one nearest to the polarity mark. Refer toAppendix
CfordistinctionbetweenFixedandDrawoutvariations.
Consultmanufactureriflengthof wire to device exceeds 12
feet(3.7m).
c. Use ring terminals on current sensor terminals. Use
AMP #66598-2 female sockets to connect to breaker’s
secondaryconnector.
d.Ground(Earth) the non polarity terminalof each sensor.
AlsoGroundthe bushing shield surfaces.
e. Install rating plug into the Digitrip 520V and 520MCV trip
units for the matching CHType-V current sensors.Also
attach the additional rating plug label to the circuit breaker
enclosureasafuturereferenceindicatingwhichCHType-V
current sensors used in this application.
1.4.2 CH Type-V Current Sensor Functionality
ThethreeCHType-V currentsensorsareinstalledexternal
to the circuit breaker over the main circuit conductors by
meansof bushingsequipped with a ground shield. The
currentsensor rating defines the breakerrating (In)...i.e.
1200A:1Asensorsare used on a 1200Aratedbreaker.
Therearefourauxiliarycurrenttransformerswitharatioof
10:1which further step down the ratedcurrent to 100 milli-
amperes, which is equivalent to 100% (In) to the Digitrip.
Theprimarycurrentsensors produce an output signal
proportionaltothe load current and furnish the Digitriptrip
unitswith the information and energy requiredto trip the
circuitbreakerwhen functional protection settings are
exceeded.
IftheCHType-V current sensors and circuitbreaker
enclosurelabelare changed to a different ratio, therating
plug must also be changed. The associated rating plug
must match the current sensors installed and as specified
onthe circuit breaker enclosure label.Refer to Figure 2.3
forCHType-Vcurrentsensorsavailable.
1.5 Plexiglass Cover
Aclear, tamper-proof,plexiglass door sits on the breaker
cover. This doorallows the settings to beviewed but not
changed,exceptbyauthorized personnel. The plexiglass
covermeetsapplicable tamper-proofrequirements.The
cover is held in place by two screws. Security is insured
by the insertion of a standard meter seal through the holes
inbothofthe cover retention screws. The plexiglass cover
has an access hole for the Reset/Battery Test push
button.
1.6 Ground Alarm/Power Supply Module (520MCV
Models Only)
TheGroundAlarm/PowerSupplyModule(SeeFigure 1.7)
is a required accessory to enable communications on the
Digitrip520MCVmodel.The module can be installed
beneath the metal mounting plate of the trip unit in the
MagnumCircuitBreaker.The module covers the following
inputvoltageratings: 120 VAC(7802C83G11),230 VAC
(7802C83G12),24-48VDC(7802C82G12) and125VDC
(7802C8213). TheburdenofthePower/Relay Module is
10VA.
Figure1.4 CHType-V Current SensorInstallation

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Figure 1.5 Secondary Block “A” Connections
Figure 1.6 Secondary Block “B” Connections

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Figure1.7 GroundAlarm/PowerSupplyModuleforthe
520MCVTripUnit
1.6.1 Auxiliary Power
When the module is wired as shown in Figure 1.8, it will
provideanauxiliary power supply so that the 520MCV
liquidcrystaldisplay (LCD) will be functional evenwhenthe
circuit breaker has no load.ADigitrip 520MCV tripunit
without auxiliary power will not display data until load
currentreaches approximately 30% 1 phase or10%
3 phaseofthe (In) rating.
1.6.2 Ground Alarm
Asecond function of the moduleis to provide eithera
groundtripor ground alarm only outputcontactvia the
relay supplied in the module.An LED on the front of the
unitalsoprovidesan indication of ground fault trip.
1.6.3 Ground Fault Trip
WhentheGroundAlarm/Power Supply module isused,
thisunit will provide ground fault trip contacts when the
circuit breaker trips on a ground fault.You must then push
the Reset button on the Digitrip in order to reset the
contacts (See Figure 1.8, Note 3).
1.6.4 Ground Fault Alarm
Aground fault alarm alerts auser to a ground faultcondi-
tion without tripping the circuit breaker.AredAlarm Only
LED on the front of the trip unit will indicate the presence
ofagroundfault condition that exceeds the programmed
setting.
Thegroundfaultalarmrelayisenergizedwhentheground
currentcontinuouslyexceeds the ground fault pickup
setting for a time in excess of a 0.1 second delay. The
alarm relay will reset automatically if the ground current is
less than the ground fault pickup (See Figure 1.8, Note 4).
1.7 Display Feature (520MCV only)
TheDigitrip520MCV model has a user interface inaddition
tothe green and red LED tripindicators. This seven
elementdisplayperforms a metering function and canbe
used to monitor load currents.
When the Step button on the face of the trip unit is
pressed and released, the display will show PH 1, for
Phase 1 orA, and the current value. If the Step button is
not pressed again, the display will continue to show the
current value for Phase 1. Each time that the Step button
is pressed, the next monitored function will be displayed.
The other real time readings can be displayed in the
followingsequence:
PH 2 Phase 2 (B)
PH 3 Phase3(C)
PH 4 Neutral
PH 5 Ground
HI Highest phase current
OL Overload(Digitripinoverloadmode)
Pushing the Step button while the unit is in the OL
modewillhavetheunitagaindisplaytheoverload
currentvalue.
HELP Thismessagecan indicate more than one problem
with the trip unit. If the rating plug is missing, a
HELPmessageand an Instantaneous trip LED
lightwillbe observed. The rating plug needstobe
installed and the Instantaneous trip LED must be
cleared by pressing the Reset/Battery Test button.

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Digitrip 520MCV
Control Voltage Remote
Ground
Fault Trip
Ground
FaultAlarm
Ground Alarm / Power Supply Module
G-Alarm
K2-1
K2-3
K2-6
Output +
Output -
J3-1
J3-2
J3-3
J4-4
J4-3
J4-1
A-10
A-11
A14
A-15
G-ALM 1 G-ALM 2
ATR Volt.
ATR COM
J4-2
Contact Rating (resistive load)
AC 0.5A @ 230VAC
AC 1A @ 120VAC
DC 1A@ 48VDC
DC 0.35A@ 125VDC
Verify input voltage rating before energizing circuit.
When used in conjunction with a T. U. Cat.
5ARMVLSIG will indicate GF trip.
120 VAC
230 VAC
24-48 VDC
7802C83G01
7802C83G02
7802C82G02
Style
Number
Available
Input Voltages 2
2
1
3
7802C82G02
7802C82G03
125 VDC
3
1
2
Inaddition, the Digitrip 520MCV will displayand freeze the
magnitudeofthetrip value after a trip event if auxilary
powerisavailable.Use the Steppushbuttonto view each
phasevalue.Thehighestvalue that can be presented is
9999.Any fault currents greater than thisvalue will be
shown as “HI.” Pushing the Reset pushbutton will clear
this data.
Alsorelatedto the phase value after a tripeventarefour
dashes“----”.This message means that the microproces-
sor could not complete its writing of the trip event’s
magnitude into its non volatile memory.Apossible cause
of this would be the lack or loss of auxilary power during
thetripevent.
Figure1.8 WiringDiagramfor520MCVwithGround
Alarm/PowerSupplyModule
This message could also indicate that the trip unit
is out of calibration and should be replaced at the
earliestopportunity.
1.8 UL, CSA and CE Recognition
TheDigitrip520Vand520MCV Trip Units are a UL®
(UnderwritersLaboratories,Inc.) RecognizedComponent
under FileE146559foruse inTypeVCP-T, VCP-TR and
Type T-VAC,T-VACR Medium VoltageCircuit Breakers.
TheyhavealsobeentestedbytheCanadianStandards
Association (CSA).
ThisDigitrip520Vand 520MCV have also passed the IEC
947-2testprogramwhichincludesradiated and conducted
emissions testing. As a result, all units carry the CE mark.
2.0 GENERAL DESCRIPTION of VCP-T, VCP-TR or
T-VAC, T-VACR CIRCUITBREAKERS
2.1 General
Thecircuitbreakersaretrippedautomaticallyonoverload
and fault current conditions by the combined action of
threecomponents:
1. Thesensors,whichmeasurethecurrentlevel
2. TheDigitripTripUnit,which provides a tripping signal to
the TripActuator, when current and time delay settings
areexceeded.
3. Thelow-energyTripActuator,which actually tripsthe
circuitbreaker.
Thisarrangementprovidesa very flexible system, covering
a wide range of tripping characteristics described by the
time-currentcurvesreferencedinSection9.2.

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2.2 Low-Energy Trip Actuator
Themechanicalforce required to initiate the tripping action
ofthecircuit breaker is provided bya special low-energy
TripActuator.Thisdevice is located behind the molded
platformonwhich the Digitrip units aresupported.(See
Figure1.2)TheTripActuatorcontainsapermanentmagnet
assembly, moving and stationary core assemblies, a
spring, and a coil. Nominal coil resistance is 25 ohms and
the black lead is positive. The circuit breaker mechanism
automatically resets the TripActuator each time the circuit
breakeropens.
When the TripActuator is reset by the operating mecha-
nism, the moving core assembly is held in readiness
againstthe force of the compressed spring bythe perma-
nent magnet. When a tripping action is initiated, the low-
energyTripActuator coil receives a trippingpulsefrom the
Digitriptripunit. This pulse overcomes the holding effectof
thepermanentmagnet, and the moving core isreleasedto
upset the trip latch of the circuit breaker mechanism.
2.3 Ground Fault Protection
2.3.1 General
Whenemployinga ground fault scheme, thedistribution
system characteristics (i.e. system grounding, number of
sources, number and location of ground points, etc.) must
beconsideredalong with the manner andlocationin which
the circuit breaker is applied to the system. These ele-
ments are discussed in Sections 2.3.2 through 2.3.4.
The Digitrip uses two modes of sensing to detect ground
faultcurrents:residual and zero sequence (SeeTable 2.1).
The breaker’s secondary contact inputs B-6, B-7, that
wereshownin Figure 1.6, are usedto configure the
breakercell positions for the two schemes.Having no
jumperfrom B-6 to B-7 programsthe unit for a residual
groundfault scheme, while installing ajumper from B-6 to
B-7programstheunitforzerosequenceconfiguration. If
present, this jumper resides on the stationary side of the
switchgearassembly.The propercurrent sensor input is
requiredon the external sensor inputterminals B-4, B-5 of
thebreaker secondary contacts.
Figure2.1 ZeroSequenceCurrentTransformer
2.3.2 Zero Sequence Sensing
ZeroSequenceSensing,alsoreferredtoasvectorial
summation, is applicable to mains, feeders, and special
schemesinvolvingzoneprotection.AnoptionalCHType-V
ZeroSequencecurrent transformer (SeeFigure2.1),having
tapsfor100Aand200Aratings isavailableforthis
application.Thetorroidalsensor has a 4.8” I.D. (12.192cm)
with a 7.6” O.D. (19.304cm). Its style number
69C3016G01.(SeeFigure 2.3 andAppendixC)
2.3.3 Residual Sensing
Residualisthestandardoperatingmodeofground fault
sensing. This mode utilizes one current sensor on each
phase conductor (See Figure 2.2). If the system neutral is
grounded,but no phase toneutral loads are used, the
Digitripincludes all ofthe components necessary for
groundfaultprotection.Thismodeofsensingvectorily
sumstheoutputsof the threeorfour individual CHType-V
currentsensors.Residualgroundfaultsensingfeatures
areadaptabletomainandfeederbreakerapplications.
Ground (Earth)
Fault
Sensing Method
Breaker Secondary
Contacts Req’d Figure
Ref
Digitrip GF
Sensing
Element Used
Residual No Jumper 2.2 element R5
Zero Sequence Jumper B6 to B7 2.3 element R4
Table 2.1 Digitrip Sensing Modes

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Figure 2.2 Breaker Using Residual GF Sensing
In this scheme, all breaker secondary currents (at the 100 mAlevel) are summed together at the PC
board donut transformer to sense ground fault via element R5.
Do not jumper secondary contacts B-6, B-7. This will defeat the residual ground fault protection.
2
1
Notes:
Source
R5
Digitrip 520V
or 520MCV
1
K2-8
Load
K1-4
K1-3
10:1
10:1 AUX. CT
K2-9
K1-5
K1-2
Black
Trip
Actuator
+
-
L
B
L
C
L
A
K1-6
K1-7
K1-8
K1-9
CSA1
A-4
A
-19 CSA2
A-5 CSB1
A
-20 CSB2
A-6 CSC1
A
-21 CSC2
X1
X2
B-5
B-4
R/1
R/1
CAUTION
IFTHE PHASE CONNECTIONSAREINCORRECT,A
NUISANCE TRIPMAY OCCUR. ALWAYS OBSERVE THE
POLARITYMARKINGSONTHE INSTALLATIONDRAW-
INGS.TOINSURE CORRECT GROUND FAULT EQUIP-
MENTPERFORMANCE, CONDUCT FIELDTESTSTO
INSUREPROPER GROUND FAULTFUNCTIONALITY.
2.3.4 Ground Fault Settings
Theadjustmentofthe ground fault functional settings
(FLAT response or I2t) is discussed in Section 4.8. The
effect of these settings is illustrated in the ground fault
time-currentcurvereferencedinSection9.The residual
ground fault pick-up settings are from 0.25x, 0.3x, 0.35x,
0.4x, 0.5x, 0.6x, 0.75x and OFF.

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Figure 2.3 Zero Sequence Sensing Scheme
Figure 2.4 Digitrip Phase Sensor (CH Type-V)
A
B
C
100A 69C3011H01 3.42 5.35 1.55
2
X
1
7
1
:
1
0
0
200A 3.42 5.35 1.55
1
7
1
:
2
0
0
250A 3.42 5.35 1.55
1
8
1
:
2
5
0
300A 3.42 5.35 1.55
1
8
1
:
3
0
0
400A 3.42 5.35 1.55
1
7
1
:
4
0
0
600A 3.42 5.35 1.55
1
8
1
:
6
0
0
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Effective 8/2006
Page 12 I.L. 66A7534H04
3.0 PRINCIPLES OF OPERATION
3.1 General
TheDigitrip520Vand520MCV trip units are designed for
circuitbreakerenvironmentswhere the ambient tempera-
turescan range from –30°C to+85°C,but rarely exceed
70°to75°C.If,however,temperatures intheneighborhood
of the trip unit exceed 85°C, the trip unit performance may
bedegraded. In order to insurethatthe tripping function is
notcompromisedduetoanover-temperaturecondition,the
Digitriptripunithasabuilt-inover-temperatureprotection
feature, factory set to trip the breaker if the chip tempera-
tureisexcessive.Ifover-temperature is the reason for the
tripthe red “Long Delay Time”LEDwill flash.
TheDigitrip520V and 520MCV use an integrated circuit
that includes a microcomputer to perform its numeric and
logicfunctions. The principles of operationofthe trip unit
areshownin Figure 3.1.
Allpowerrequired to operate the protection functionis
derivedfromtheCHType-Vcurrentsensorsintheenclo-
surebehindthe circuit breaker.(SeeFigure1.4)The
secondarycurrentsfromthese sensors provide the correct
inputinformation for the protection functions,as well as
trippingpower, whenever the circuit breaker is carrying
current.Thesecurrent signals develop analog voltages
acrossthe“currentviewing”resistors.Theresultinganalog
voltagesare digitized by the microprocessor.
Themicrocomputer continually digitizes these signals.
This data is used to calculate true RMS current values,
whicharethen continually compared with the protection
settings.Theembeddedsoftwarethen determines whether
toinitiate protection functions, including tripping the
breakerthroughtheTripActuator.
3.3 Zone Interlocking
CAUTION
IF ZONE INTERLOCKING IS NOT TO BE USED (I.E.,
ONLYSTANDARDTIME-DELAY COORDINATIONIS
INTENDED),THE ZONEINTERLOCKING TERMINALS
MUSTBE CONNECTED BY AJUMPER FROM TERMI-
NALB8 TO B9OF THE BREAKER SECONDARYTERMI-
NALS SO THAT THE TIME-DELAY SETTINGS WILL
PROVIDETHE INTENDEDCOORDINATION.
ZoneSelectiveInterlocking(or Zone Interlocking) is
standardfor the Digitrip trip unit on the “Short Delay” and
“GroundFault”protectionfunctions(See Figure 3.1). The
zone interlocking signal is wired via a single set of wires
labeledZoneIn(Zin)and Zone Out (Zout) along with a
“ZoneCommon” wire. TheZoneSelectiveInterlocking
function on the Digitrip has combined the logic interlocking
of “Short Delay” and “Ground Fault.” Azone out signal is
sentwheneverthegroundfaultpick-upisexceeded or
whenthe short delay pickup is exceeded.Zone Selective
Interlockingprovidesthefastestpossibletripping for faults
within the zone of protection of the circuit breaker and yet
alsoprovidespositivecoordinationamongallbreakersin
the system (mains, ties, feeders, and downstream break-
ers) to limit a power outage to only the affected parts of the
system. When Zone Interlocking is employed, a fault
within the zone of protection of the circuit breaker will
cause the Digitrip 520V and 520 MCV to simultaneously:
1)Trip the affected circuit breaker immediately
2)Send a signal to upstream Digitrip units to restrain from
trippingimmediately.Therestraining signal causes the
upstreambreakers to follow their setcoordination times,
so that the service is only minimally disrupted while the
fault is cleared in the shortest time possible.
Foranexampleofhow Zone Selective Interlocking may be
used, seeAppendixAof this Instructional Leaflet.
3.2 Trip and Operation Indicators
The LEDs on the face of the trip unit, shown in Figures 1.1
flash red to indicate the reason for any automatic trip
operation. Each LED is strategically located in the related
segmentofthe time-current curve depicted on the faceof
the trip unit. The reason for the trip is identified by the
segmentofthe time-current curve where the LEDis
illuminated.Followingan automatic trip operation, the
backup battery continues to supply power to the LEDs as
shown in Figure 3.1. The LED pulse circuit, shown in
Figure3.1,is provided to reduce battery burden and will
supply a quick flash of the trip LED approximately every 4
seconds. It is therefore important to view the unit for at
least 5 seconds to detect a flashing cause of trip indicator.
Following atrip operation, push the Reset/BatteryTest
button, shown in Figure 1.1, to turn off the LEDs and reset
the trip unit.
The green Unit Status LED, shown in Figure 1.1, flashes at
onesecond intervals to indicate the operationalstatus of
the trip unit. Once the load current through the circuit
breakerexceedsapproximately10 percent(3phase
power)ofthe current sensor rating, the greenLEDwill
flash on and off once each second to indicate that the trip
unitisenergizedandoperatingproperly.
NOTE:Asteady green Unit Status LED typically indicates
that a low level of load current, on the order of 5% of full
load, exists.

Effective 8/2006
Page 13
I.L. 66A7534H04
ABC
AUX CTs
Residual
Ground
Detection
Typical Phase or Ground Sensing Resistor
Bridge
Circuits Internal
Power
Supply
Trip Actuator
LED
Pulse
Circuit
Battery
+ 3V
FET
Trip
(See Section 1.2)
Trip LEDs
Rating Plug
Integrated
Processor
Custom
Designed
TA
Unit Status LED
(See Section 3.2)
(See Section 7.0)
(See Section 2.3) (See Section 3.3)
Zone Interlock
Circuitry ZIn
ZOut
Current Sensors
(See Section 1.4)
(See Section 4.0)
Protection Setting
4 bit Latch Chip
(See Section 6.0)
(See Section 2.2)
Figure 3.1 Block Diagram with Breaker Interface

Effective 8/2006
Page 14 I.L. 66A7534H04
4.0 PROTECTION SETTINGS
4.1 General
Before placing any circuit breaker in operation, set each
trip unit protection setting to the values specified by the
engineer responsible for the installation. Each setting is
made by turning a rotary switch, using a small screwdriver.
Theselected setting for each adjustment appearson the
trip unit label.
NOTE:The installedrating plugmust match the CHType-
V current sensors which establish the maximum continu-
ouscurrentrating of the circuit breaker(In). Instantaneous
andgroundcurrent settings are defined in multiplesof (In).
To illustrate the effectof each protection curve setting,
simulatedtime-currentcurvesare pictured on the face of
the trip unit. Each rotary switch is located nearest the
portionof the simulated time-current curve that it controls.
Should an automatic trip occur (as a result of the current
exceedingthepre-selectedvalue),theLEDintheappropri-
atesegment of the simulated time-current curvewill light
red, indicating the reason for the trip.
Theavailablesettings,alongwiththe effects of changing
the settings, are given in Figures 4.1 through 4.8. Sample
settingsare represented in box.
4.2 Long Delay Current Setting
Thereareeightavailable“LongDelaySettings”asillus-
trated in Figure 4.1. Each setting, called (Ir), is expressed
as a multiple (ranging from .4 to 1) of the current (In). The
nominal current pickup value is 110% of the setting.
NOTE: (Ir) is also the basis for the “Short Delay Current
Setting” (see Section 4.4).
Figure4.1 LongDelayCurrent Settings
4.3 Long Delay Time Setting
ThereareeightavailableLongDelayTimeSettings,as
illustrated in Figure 4.2, ranging from 2 to 24 seconds.
These settings are the total clearing times when the
currentvalueequals 6 times (Ir).
Figure 4.2 Long Delay Time Settings
NOTE: Inadditiontothestandard “Long Delay Protection
Element,”tripunitsalsohavea“LongTimeMemory” (LTM)
function, which protects load circuits from the effects of
repeatedoverloadconditions.Ifacircuit breaker is
reclosedsoonafter a Long Delay Trip, andthecurrent
againexceeds the Long Delay Setting, (Ir),the LTM
automatically reduces the time to trip to allow for the fact
that the load circuit temperature is already higher than
normalbecauseoftheprior overload condition. Each time
theoverloadcondition is repeated, the LTM causesthe
breaker to trip in a progressively shorter time. When the
load current returns to normal, the LTM begins to reset;
after about 10 minutes it will have reset fully, so the next
Long Delay trip time will again correspond to the setting
value.
NOTE: In certain applications, it may be desirable to
disable the LTM function. Open the test port located at the
lowerleft-hand front of the tripunit and use small, long-
nose pliers to move the LTM jumper inside the test port
(SeeFigure4.3) to itsInactiveposition.(TheLTM function
can be enabled again at any time by moving the LTM
jumper back to its original active position.)

Effective 8/2006
Page 15
I.L. 66A7534H04
Connector
(Storage)
“LTMActive
”
Connector
(Bridging)
“LTM Inactive
”
Test
Kit
Test
Kit
(Also Recommended
Position for
Field Testing)
Digitrip Test Kit Port
Notch
Available Settings
1.5, 2, 3, 4, 6, 8, 10, M1
In Multiples of
Long Delay Setting (r)I
Short Delay
Setting
M1 Value is Specified on Rating Plug
2 x rI
Figure 4.5 Short Delay Time Settings
Five FLAT (.1, .3, .4, .st1,st2 seconds) and three I2t (.1*,
.3*, .5* seconds) response time delay settings are avail-
able. The I2t response settings are identified by an asterisk
(*). The time settings labeled st1 and st2 are based on the
rating plug. For 100A st1 and st2 =0.5s. For 200A through
400A, st1 = 0.5s and st2 = 1s. For rating plugs 600A and
greater, st1 =1s and st2 = 2s.The I2t response is appli-
cable to currents less than 8 times the ampere value of Ir
rating.For currents greater than 8x (Ir)theI2t response
revertsto the FLATresponse.
NOTE: Also see Section 3.3 - Zone Interlocking.
4.6 Instantaneous Current Setting
ThereareeightavailableInstantaneous current settings,
as illustrated in Figure 4.6. Six settings are in the range
from 2 to 10 x (In) the rating plug value, and the other two
settings are M1 x (In) and Off. The value that M1 has
depends upon the plug rating of the circuit breaker and is
specified both on the rating plug label and on the
applicabletime-currentcurvesreferencedinSection9.
Figure4.3 LongTimeMemory (LTM)Jumper
TheactionoftheLTMmustbeconsideredwhen performing
multiple Long Delay Time tests (See Section 5.4).
4.4 Short Delay Current Setting
Thereareeightavailable“ShortDelayCurrentSettings,”as
illustrated in Figure 4.4. Seven settings are in the range
from 1.5 to 10 times (Ir). However there exists an addi-
tional maximum setting M1 that is based on (In).It is set
for14x(In) for all rating plugs upto1250Aand 12X for
2000A,2500A.
REMINDER: (Ir)isthe“LongDelayCurrent Setting.”
Figure4.4 ShortDelay Current Settings
4.5 Short Delay Time Setting
Asillustrated in Figure 4.5, thereare two different “Short
Delay”responsecurveshapes:fixed time (FLAT)and I2t.
Theshapeselected depends on the type ofselective
coordinationchosen.TheI2tresponsecurvewillprovidea
longer time delay for current below 8 x Irthan will the FLAT
responsecurve.
.,.,., , 134st1st2
PLUG st1 st2
100A 0.5
200-400A
0.5
0.5 1.0
1.0 2.0
600-2500A

Effective 8/2006
Page 16 I.L. 66A7534H04
Figure4.6 InstantaneousCurrent Settings
4.7 Ground Fault Current Setting
Theeight“GroundFaultCurrentSettings”arelabeledwith
values from .25 to .75 x (In) and the other one is OFF.
(SeeFigure4.7).Thespecific“GroundCurrentSettings” for
each model are listed in Figure 4.7 and on the applicable
time-currentcurveforthecircuitbreaker.
Figure4.7 GroundFault Current Settings
4.8 Ground Fault Time Delay Setting
Asillustratedin Figure 4.8, there are twodifferentGround
Faultcurveshapes: fixed time (FLAT)or I2t response.The
shapeselecteddepends on the type of selective coordina-
tionchosen.The I2t response will provide a longertime
delay for current below 0.625 x In than will the FLAT
response.
Five FLAT (.1, .2, .3, .4, .5 seconds) and three I2t (.1*, .3*,
.5* seconds)responsetime delay settings are available.
The I2t response settings are identified by an asterisk (*).
The I2t response is applicable to currents less than 0.625
times the ampere rating of the installed rating plug (In). For
currentsgreater than 0.625 xIn theI2t response reverts to
theFLATresponse.
NOTE: Also see Section 3.3 - Zone Interlocking.
M1 value is specified on rating plug.
Setting Inst.
x nI
6
A
vailable Settings
2, 3, 4, 6, 8,
10, M1, OFF
In Multiples of
Rating Plug
Amperes ( n)I
Available Settings
0.25, .3, .35, .4,
.5, .6, .75, OFF
Gnd-Fault
Setting
x nI
.4
Figure 4.8 Ground Fault Time Delay Settings
4.9 INCOM (Digitrip 520MCV Models only)
INCOM communication to a host computer or a BIM is
possiblewiththe Digitrip 520MCV unit. The address range
is 001 through 999. The factory default address is 999 hex.
To set the desired address or to view the address, depress
andholdtheRESET/BATTERYTESTbutton forfive
seconds. Depress the STEP button to select a new
address. Users may simultaneously depress and hold in
theSTEPand RESET/BATTERYTESTbuttonsfor fast
advance.
4.9.1 Breaker Interface Module (BIM)
TheBreakerInterfaceModule(BIM)canbe used to
monitor up to 31 Digitrip 520MCV trip units. The accept-
ableaddressesare001through031.
4.9.2 Remote Master Computer
Whendesired,Digitrip 520MCV Trip Units can communi-
cate with a BIM or remote master computer (IBM PC
compatiblewithCutlerHammerInc. CONI card or MINT )
andusingPowerNetcommunication software version 3.20
orgreater.(See Figure 4.9 for typical wiring.)

Effective 8/2006
Page 17
I.L. 66A7534H04
These bursts of data can be captured and used in a variety
ofwaysdepending upon the manner in whichthemaster
computersoftware program is written. For example,all the
settingscanbeviewed via the master computer.Another
exampleis that the data fortheindividual phase current
valuesareavailableonthe network, but the software must
select the appropriate data, decode it and display it in a
usefulmanner. Following anover-currenttripoperation,the
sequenceof coded datavariesslightly.Thecause of trip,
thevalue,thephase(orground)currentresponsibleforthe
tripareavailableonthenetwork.
1
1
2
3
Notes:
Refer to Master Circuit Breaker Connection Diagrams in Appendix C.
Modular telephone connector, Type RJ11, supplied by user.
Ground shielding at computer and BIM as shown. Where devices
aredaisy-chained, interconnect shielding, but do not ground the connection.
100 ohm 1/2 watt carbon terminating resistor required at last breaker. See T.D. 17-513.
See Section 4.9 for programming INCOM function.
0 0 1 0 0 2
Cut-off Shield or connect to
unused customer
terminal -- Do not Ground.
Twisted Pair.
No. 18AWG.
Breaker
Interface
Monitor
(BIM)
C-H Coni. Card
Typical Magnum
Circuit Breaker
with Digitrip 520MCV Trip Unit 3 Digit INCOM Address
as displayed on Tripunit
H = 9600 Baud
See View A
Typical IBM
Compatible
Computer
View A
(Y)
(BL)
3
3
2
Figure4.9 INCOMNetworkwith Remote Master Computer or BIM
4.9.3INCOM Network Interconnections
INCOM sends bursts of data on a 92 to 115.2 kHz carrier
ata 9600 baud rateover twisted pair conductorsto
interconnectthemany devices comprising the network.
TheDigitrip520MCV will light the redLED shown in Figure
1.1whentransmittingonINCOM.
Recommendedcablespecifications:
• Cutler-HammerInc.cablecatalog#IMPCABLE,
Style#2A95705G01
• Belden9463cablefamily
• IdenticalCommscopeorQuabbincables

Effective 8/2006
Page 18 I.L. 66A7534H04
WARNING
ANY TRIPPING OPERATION WILLCAUSE DISRUPTION
OF SERVICEAND POSSIBLE PERSONAL INJURY,
RESULTING IN THEUNNECESSARYSWITCHING OF
CONNECTEDEQUIPMENT.
CAUTION
TESTING A CIRCUIT BREAKER WHILE IT IS IN-SER-
VICEAND CARRYING LOADCURRENTIS NOTRECOM-
MENDED.
TESTING OFACIRCUIT BREAKER THAT RESULTS IN
THETRIPPING OF THE CIRCUITBREAKERSHOULD
BEDONE ONLYWITH THECIRCUIT BREAKER IN THE
TESTORDISCONNECTED CELL POSITIONS OR
WHILE THE CIRCUIT BREAKER IS ON A TEST BENCH.
5.2 When to Test
ForDraw-Out Breakers, testing of theDigitriptrip unit prior
to start-up can best be accomplished with the circuit
breaker out of its cell or in theTest, Disconnected, or
Withdrawn(orRemoved)cellpositions.
NOTE: Sincetime-currentsettings are based on desired
system coordination and protection schemes, the protec-
tion settings selected and preset in accordance with
Section 4.0 should be reset to their as-found conditions if
alteredduringany routine test sequence.
Model Test Kit
Digitrip 520V
and 520MCV TestKit (140D481G02R, 140D481G02RR, 140D481G03,or G04) with Test Kit Adapter
8779C02G04
5.3 Functional Field Testing
5.3.1 Field Test Kit
Use the test receptacle to verify a functional load test of a
major portion of the electronic circuitry of the Digitrip trip
unit and the mechanical trip assembly of the circuit
breaker.The testing can determine the accuracy of the
desiredtripsettings by performing Long Delay, Short
Delay, and Ground Fault functional tests. The Cutler-
Hammerapproved test kitis listed below.
The test port is located on the front left-hand corner of the
trip unit (See Figure 1.1). To access the port, remove the
plexiglasscoverfrom the front of thecircuitbreaker.Using
a small screwdriver, gently pry up on the test port cover to
removethisitem.
CAUTION
BEFORE PLUGGING A TEST KIT INTO THE TEST
PORT, PLACE THE LTM JUMPER IN THE INACTIVE
POSITION (See Figure 4.3). AFTER TESTING, RE-
TURN THE LTM JUMPER TO ITS ORIGINAL POSITION.
Thetest kit authorized by Cutler-Hammer for use with the
Digitrip 520V and 520MCV, plugs into the test port of the
trip unit and provides a secondary injectionAC test current
that simulates the CH Type-V current sensors. Test kits
styles140D481G02R, 140D481G02RR,140D481G03or
G04, along with the Test KitAdapter 8779C02G04, can be
used to test the trip unit and circuit breaker.
CAUTION
PERFORMING TESTS WITHOUT THE CUTLER-
HAMMER-APPROVED TESTKIT MAYDAMAGE THE
DIGITRIP UNIT.
5.0 TESTPROCEDURES
5.1 Test Precautions
WARNING
DO NOT ATTEMPT TO INSTALL, TEST, OR PERFORM
MAINTENANCEON EQUIPMENT WHILE IT ISENER-
GIZED.DEATHOR SEVEREPERSONALINJURYCAN
RESULTFROM CONTACTWITHENERGIZED EQUIP-
MENT.
DE-ENERGIZETHECIRCUITANDDISCONNECT THE
CIRCUITBREAKER BEFOREPERFORMINGMAINTE-
NANCEOR TESTS.

Effective 8/2006
Page 19
I.L. 66A7534H04
5.3.2 Handheld Functional Test Kit
5.3.2.1 Description of Handheld Test Kit
A battery powered test kit is also available and capable of
testing trip elements for Digitrip 520V and 520MCV units,
includingpowerup,InstantaneousTrip,ShortDelayTrip,
andGround(Earth) Fault Trip. These test selectionsare
chosen with the switch labeled Select Test located in the
upper right hand corner of the test kit (See Figure 5.1).
The test currents are DC currents set at the factory and
arenotadjustable.
Thestylenumberof this device is # 70C1056G52
(120VAC)or #70C1056G53(230VAC).
5.3.2.2 Test Procedure
CompleteproceduralinstructionsfortheCutlerHammer
Mini Test Kit can be found in I.L. # 5721D13 which is
packaged with each test kit.
NOTE:After completion of testing,
1.Disconnectsecondary connector with jumper
2. Disconnect test input cable
3. Reposition all trip unit settings to “as found”
4.RepositiontheLTM (LongTimeMemory) jumper
5. Reinstall the test port cover on the Digitrip
6. Reinstall plexiglass cover to circuit breaker
5.3.2.4 Batteries
This Functional Test Kit contains a total of seven 9-Volt
batteries.Alithium ion cell is the preferred battery type for
Battery Voltage (A) and is attached to the main pc board of
the test kit. This battery has a much longer life span to
accurately perform the selected tests. The remaining six
batteries are located on a separate board in the test kit
and serve to power up the Digitrip trip unit.
Battery status LED’sAand B function to represent
sufficientvoltage from both thesingle lithium cell andthe
sixAlkaline batteries, respectively. If either LED does not
light or lights dimly, replace the appropriate battery or
batteries within the test kit case. To do this, open the back
ofthecaseusing a screwdriver and remove the batteryor
batteries from their respective locations. For best results,
replacelithiumbattery (BatteryA) with ULTRALIFE®U9VL
Battery. When replacing battery six-pack (Battery B),
replace all batteries at the same time using standard 9V
alkalinebatteries.
5.4 Performance Testing of Digitrip 520V and 520MCV
TripUnits
5.4.1 General
Thecomplete circuit breaker should be testedafter sensor
wiring is completed. TheAVO Multi-Amp®model MS-2 or
equivalentcurrent source can be used to perform this test
(SeeFigure5.2).
Figure 5.1 Functional Test Kit
5.4.2 Testing using MS-2 Multi AMP®Tester
5.4.2.1 Description of MS-2 Tester
Theportable(33lb/15kg)AVO MultiAMP®tester,model
MS-2 can be used to check out Digitrip 520V. There are
two levels of testing that can be done.Aprimary or
secondary injection test can be done. The primary injection
testisgood for verifying both CHType-Vcurrent sensor
polarityandhookup through the circuit breaker’s secondary
5.3.2.3Currents
Each test chosen by the Select Test switch on the test kit
suppliesafixedmilliamperecurrentvalue.
NOTE: TheLongDelaySetting will affect the perunit(Ir)
currentvalue.

Effective 8/2006
Page 20 I.L. 66A7534H04
secondary injection current. This is because of the trip
unit’s“chopper” powersupply.Thepeakholdfeaturewill
holdthe trip current levelwhen an auxilary switch from the
circuit breaker is wired back to the tester’s terminals
(white posts)labeled Contacts.
3.Also when performing low currentsecondaryinjection
tests (less than 2Amperes) it is desirable to insert an
additional25ohm impedance (resistor or inductor) rated at
25 or 50 watts in series with the 5A terminal post. This will
provideproperimpedanceforthe “chopper” and is useful in
stablizing thecurrent (See Figure5.5).
5.4.2.2 Primary Injection Testing
Preliminary hookup:
Figure 5.2 AVO MultiAmp®MS-2 Test Source
a. Connect anAux Switch or unused unused circuit
breaker pole to the Contacts input terrminals of the MS-2
currentsourceto hold current ramp value level andtostop
thetimer.
contacts and into the Digitrip trip unit. This is a complete
system checkout and is strongly recommended after initial
setupandbefore enerizating of the gear.Although theMS-
2 source is limited to 600 amperes (momentary), it can
verifythatthe trip unit powers up properlyandperform a
ground fault trip of the circuit breaker. This testing at the
primaryinjection level is able toverify that the breaker’s
response to each primary phase current is correct. The
secondary injection current source is able to deliver up to
5x (1 ampere is 1 per unit) into the breaker’s secondary
contacts. This can produce a 300% overload test and a
400%ShortTime or Instantaneous test.
Thefollowingextracomponentsaredesirable additions for
the testing.
1. For the primary injection testing, three separate flexable
(weldingtype) cables (#2AWG or larger) andeach about 3’
(.914m)long,arerequiredtobefabricated.Connectors,
with tabs, need to be attached on each end to connect to
the tester’s terminal studs. The flat tab extension will also
providea surface to attachedto the gear’s busconductors
using C-clamps.Atypical connector style would be an
ILSCOstyle SLS125.
2. For secondary injection tests, a separate True RMS
ammeterwitha“peakhold” feature is required (See Figure
5.5). The built in meter of the MS-2 tester is not True RMS
anddoesnotprovideanaccuratemeasurementofthe
b.SetDigitrip Ground Setting to“0.4”and remove (if any)
jumpers connected on secondary points B-6, B-7 (See
Figure1.6).
c. Connect one end of the primary current cables to the
240A and Common posts of the MS-2 test source.
Connect the other ends to the line and load side of the
breaker’sleftpole(Phase“A”).Thiswillprovideaprimary
currentthroughCHType-Vcurrentsensor for the test.
d. Set MS-2 built-in meter to 750A scale.
IMPORTANT: Do the following test even if ground fault is
to be set to OFF or Zero Sequence Sensing is chosen for
thefinalapplication.