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December 2013

Contents

Molded-Case Circuit Breakers & Enclosures27

Sheet 27001

M o

l d e d - C a s e

C i r c u

i t

B r e a k e r s &

E n c l o s u r e s

Molded-Case Circuit Breakers & Enclosures

Breaker Type Comparison

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.0-2

Table of Contents

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.0-3

General Description

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.1-1Special Function Circuit Breakers

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.2-1

Application Data

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-1

Circuit Breaker Selection Data

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.4-1

Specifications

See Eaton’s Product Specification Guide

, available on CD or on the Web.

CSI Format: . . . . . . . . . . . . . . . . . . . . . . . . . 1995 2010

Molded-Case Circuit Breakers . . . . . . . . Section 16475 Section 26 28 11

Electronic Trip Units. . . . . . . . . . . . . . . . Section 16904 Section 26 28 50

Enclosed Circuit Breakers . . . . . . . . . . . Section 16476 Section 26 28 16.11

Molded-Case Circuit Breakers


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Breaker Type Comparison

002

Summary of Differences Between Low Voltage Power Circuit Breakers,Insulated-Case Circuit Breakers and Molded-Case Circuit Breakers

There are two main classifications of low voltage circuitbreakers—molded-case circuit breakers and low voltagepower circuit breakers. All UL

®

, NEMA

®

and ANSI standards

are for molded-case circuit breakers and low voltagepower circuit breakers.

The industry recognizes three types of circuit breakers—molded-case circuit breakers (MCCB), insulated-case circuitbreakers (ICCB) and low voltage power circuit breakersLVPCB). Insulated-case circuit breakers are designed tomeet the standards for molded-case circuit breakers.

Low voltage power circuit breakers comply with thefollowing standards:

■

ANSI Std. C37.16—Preferred Ratings

■

ANSI Std. C37.17—Trip Devices for LVPCB

■

ANSI Std. C37.50—Test Procedures

■

IEEE

®

Std. C37.13—LVPCB Used in Enclosures

■

UL 1066—LVPCB

Molded-case circuit breakers and insulated-case circuitbreakers typically comply with the following standards:

■

UL 489—MCCB

■

UL 489—Molded-Case Switches (MCS)

■

NEMA AB1—MCCB and MCS

■

NEMA AB3—MCCB Application

Table 27.0-1. Breaker Type Comparison Chart

Description LVPCB

(Type Magnum™ DS and Series NRX™)

ICCB

(Type Magnum SB and Series NRX)

MCCB

(QUICKLAG/Series C

®

/Series G

®

)

Select tripshort-time rating

Selective trip over full range of faultcurrents up to interrupting rating(high short-time ratings)

Selective trip over partial range of faultcurrents within the interrupting rating(medium short-time ratings). Typicallyup to 35 kA

Selective trip over a smaller range of faultcurrents within the interrupting rating (lowshort-time ratings). Typically 10–13 timesthe frame size

Operator type Types of operators: mechanicallyoperated and electrically operatedtwo-step stored energy

Types of operators: mechanicallyoperated and electrically operatedtwo-step stored energy

Types of operators: mechanically operatedover-center toggle or motor operator

Closing speed 5-cycle closing for electricallyoperated devices

5-cycle closing for electricallyoperated devices

Greater than 5-cycle closing for electricallyoperated devices

Mounting Available in drawout constructionpermitting racking to a distinct “testposition” and removal for maintenance

Available in drawout constructionpermitting racking to a distinct “testposition” and removal for maintenance

Typically fixed-mounted but large framesizes may be available in drawoutconstruction

Interrupting rating Interrupting duty at 635 Vac:42–100 kA and current limiting withor without fuses up to 200 kA

Interrupting duty at 508 Vac:35 –150 kA

Interrupting duty at 480 Vac:22–100 kA without fuses and upto 200 kA with integral fuses or forcurrent-limiting type

Current limiting Special current limiting types availablewith or without fuses up to 200 kA

Special current limiting types availablewithout fuses up to 150 kA

Current limiting available with and withoutfuses up to 200 kA

Relative cost Higher Medium Low

Availableframe sizes

Small number of frame sizes available.Typical 800–6000A

Small number of frame sizes available.Typical 800–6000A

Large number of frame sizes available.Typical 100–2500A

Maintenance Extensive maintenance possible on allframe sizes

Limited maintenance possible on largerframe sizes

Very limited maintenance possible on largerframe sizes

Enclosure types Used in enclosures, MCCs, switchboardsand switchgear

Used in enclosures, MCCsand switchboards

Used in enclosures, panelboards,switchboards, MCCs and control panels

Series ratings Not available in series ratings Not available in series ratings Available in series ratings

Enclosed rating 100% continuous current rated inits enclosure

80% continuous-current rated, unlessspecifically stated to be rated 100% inan enclosure

80% continuous-current rated, unlessspecifically stated to be rated 100% inan enclosure

Standards ANSI/IEEE C37UL 1066

NEMA AB1/AB3UL 489 or UL 1066

NEMA AB1/AB3UL 489


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003


Series G

Table of Contents

General Description

Circuit Breaker Components and Functions . . . . .

27.1-1

Electronic RMS Trip Units . . . . . . . . . . . . . . . . . . . .

27.1-2

Accessories and Modifications . . . . . . . . . . . . . . . .

27.1-7

Special Function Circuit Breakers

Molded-Case Switches . . . . . . . . . . . . . . . . . . . . . .

27.2-1

Motor Circuit Protectors . . . . . . . . . . . . . . . . . . . . .

27.2-1

Current Limiting Breakers . . . . . . . . . . . . . . . . . . . .

27.2-3

100% Rated Breakers. . . . . . . . . . . . . . . . . . . . . . . .

27.2-5

Series Rated Breaker Combinations. . . . . . . . . . . .

27.2-8

High Instantaneous Breakers forSelective Coordination . . . . . . . . . . . . . . . . . . . . .

27.2-12

Earth Leakage Circuit Breakers . . . . . . . . . . . . . . . .

27.2-12

AFCI Circuit Breakers . . . . . . . . . . . . . . . . . . . . . . . .

27.2-13

DC Rated Breakers . . . . . . . . . . . . . . . . . . . . . . . . . .

27.2-14

400 Hz Breaker Application . . . . . . . . . . . . . . . . . . .

27.2-16

HID Rated Breakers . . . . . . . . . . . . . . . . . . . . . . . . .

27.2-19

Lighting Control Solenoid Operated Breakers . . .

27.2-19

SWD Rated Breakers . . . . . . . . . . . . . . . . . . . . . . . .

27.2-19

HACR Rated Breakers . . . . . . . . . . . . . . . . . . . . . . .

27.2-19

Engine Generator Circuit Breakers . . . . . . . . . . . . .

27.2-19

Mining Circuit Breakers . . . . . . . . . . . . . . . . . . . . . .

27.2-20

Naval/Marine Rated Breakers . . . . . . . . . . . . . . . . .

27.2-20

Welding Circuit Breakers. . . . . . . . . . . . . . . . . . . . .

27.2-20

Application Data

Continuous Ampere Rating. . . . . . . . . . . . . . . . . . .

27.3-1

Circuit Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-1

Interrupting Ratings. . . . . . . . . . . . . . . . . . . . . . . . .

27.3-1

Circuit Frequency . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-2

Number of Poles . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-2

Ground Fault Protection . . . . . . . . . . . . . . . . . . . . .

27.3-2

Code Considerations . . . . . . . . . . . . . . . . . . . . . . . .

27.3-2

Service . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-2

Feeder Circuits . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-2

Branch Circuits . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-2

Circuit Breakers Not hp Rated . . . . . . . . . . . . . .

27.3-3

Motor Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-4

Capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-6

Transformers . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-6

Slash Rating . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-7

Cable Sizing/Selection . . . . . . . . . . . . . . . . . . . .

27.3-8

Time Current Curve Characteristics . . . . . . . . . . . .

27.3-9

Selective Coordination . . . . . . . . . . . . . . . . . . . . . .

27.3-10

Breaker Selection Table—100% Selective . . . .

27.3-14

Breaker Selection Table—0.1 Sec Selective . .

27.3-22

Arc Flash. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.3-35

Arcflash Reduction Maintenance System . . . . . . .

27.3-36

Unusual Environmental Conditions . . . . . . . . . . . .

27.3-37

Reverse-Feed Applications . . . . . . . . . . . . . . . . . . .

27.3-38

Circuit Breaker Selection Data

Overview Tables . . . . . . . . . . . . . . . . . . . . . . . . . . .

27.4-1

QUICKLAG

®

Industrial Circuit Breakers . . . . . .

27.4-1

Series G Industrial Circuit Breakers . . . . . . . . .

27.4-4

Series C Industrial Circuit Breakers. . . . . . . . . .

27.4-5

Current Limiting Industrial Circuit Breakers. . .

27.4-6

Industrial Circuit Breakers in Assemblies. . . . .

27.4-7

Electronic Trip Units . . . . . . . . . . . . . . . . . . . . . .

27.4-8

Digitrip OPTIM . . . . . . . . . . . . . . . . . . . . . . . . . .

27.4-10

Individual Circuit Breaker Selection Data . . . . . . .

27.4-11

QUICKLAG Industrial Circuit Breakers . . . . . . .

27.4-11

QUICKLAG Solenoid-OperatedCircuit Breakers . . . . . . . . . . . . . . . . . . . . . . . .

27.4-13

Series G Industrial Circuit Breakers . . . . . . . . .

27.4-19

Series C Industrial Circuit Breakers. . . . . . . . . .

27.4-25

Series G Breaker Accessories . . . . . . . . . . . . . .

27.4-33

Series C Breaker Accessories . . . . . . . . . . . . . .

27.4-34

High Instantaneous Circuit Breakerfor Selective Coordination . . . . . . . . . . . . . . .

27.4-35

Motor Circuit Protectors (MCP) . . . . . . . . . . . . .

27.4-38

Motor Protector Circuit Breaker (MPCB). . . . . .

27.4-40

Power Monitoring and MeteringModule (PM3). . . . . . . . . . . . . . . . . . . . . . . . . .

27.4-41

Earth Leakage Circuit Breakers . . . . . . . . . . . . .

27.4-44

Current Limiting Modules and Breakers. . . . . .

27.4-45

Circuit Breaker Enclosures. . . . . . . . . . . . . . . . .

27.4-50


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General Description005

General Description

General CircuitBreaker Information

Eaton’s molded-case circuit breakers

are designed to provide circuitprotection for low voltage distributionsystems. They are described byNEMA as, “. . . a device for closingand interrupting a circuit betweenseparable contacts under both normaland abnormal conditions,” and further-more as, “. . . a breaker assembledas an integral unit in a supportingand enclosing housing of insulatingmaterial.” The NEC® describes themas, “A device designed to open andclose a circuit by non-automaticmeans, and to open the circuitautomatically on a predeterminedoverload of current, without injury

to itself when properly applied withinits rating.”

So designed, Eaton circuit breakersprotect conductors against overloadsand conductors and connectedapparatus, such as motors andmotor starters, against short circuits.

Circuit Breaker Componentsand Functions

Being essentially high interruptingcapacity switches with repetitiveelements, Eaton circuit breakersare comprised of three mainfunctional components. These are:

1. Trip elements (thermal-magneticor electronic)

2. Operating mechanism3. Arc extinguishers

1. Trip Elements

The function of the trip element is to tripthe operating mechanism in the eventof a prolonged overload or short-circuitcurrent. To accomplish this, a thermal-magnetic trip action is provided.

Thermal-Magnetic Breakers

Eaton thermal-magnetic breakers aregeneral purpose devices suitable forthe majority of breaker applications

and are considered the industry stan-dard. Available from 15–800A, thermal-magnetic breakers provide accuratereliable overload and short-circuitprotection for conductors andconnected apparatus.

Thermal trip action is achievedthrough the use of a bimetal heated bythe load current. On a sustained over-load, the bimetal will deflect, causingthe operating mechanism to trip.Because bimetals are responsive to

the heat emitted by the current flow,they allow a long-time delay on lightoverloads, yet they have a fastresponse on heavier overloads.

Magnetic trip action is achieved throughthe use of an electromagnet in serieswith the load current. This provides aninstantaneous tripping action when thecurrent reaches a predetermined value.Front-adjustable magnetic trip elementsare supplied as standard on 250A framecircuit breakers and above (except 100Aand 150A magnetic only breakers), allother thermal-magnetic breakers havenon-adjustable magnetic trip elements.

Electronic RMS Trip BreakersEaton electronic trip breakers aregenerally applied for applicationswhere high levels of system coordina-tion are called for. Available from20–2500A, today’s electronic tripbreakers can provide superiorprotection and coordination as wellas system alarms and diagnostics,monitoring and communications.

Both the overload trip action and theshort-circuit trip action of breakerswith Digitrip electronic trip unitsare achieved by the use of currenttransformers and solid-state circuitrythat monitors the current and initiatestripping through a flux shunt tripwhen an overload or a short circuitis present. All multiple-pole circuitbreakers have trip elements in eachpole and a common trip bar. Anabnormal circuit condition in anyone pole will cause all poles to opensimultaneously.

Electronic RMS trip breakers caninclude trip features such as:

■ Adjustable long-time pickup

■ Adjustable short-time pickup

■ Adjustable long delay time

■ Adjustable short delay time

■ Adjustable instantaneous pickup

■ Adjustable ground fault pickup

■ Adjustable ground fault delay time

■ Zone selective interlocking

■ Communications

Trip unit adjustments are made bysetting switches on the front of the tripunit or by programming the trip unitelectronically.

All electronic RMS trip breakers areequipped with a manual push-to-trip

mechanism.

2. Operating Mechanism

The function of the operating mecha-nism is to provide a means of openingand closing the breaker contacts. Allmechanisms are of the quick-make,quick-break type and are “trip free.”“Trip free” mechanisms are designedso that the contacts cannot be heldclosed against an abnormal circuitcondition and are sometimes referredto as an “overcenter toggle mechanism.” In addition to indicating whether thebreaker is “on” or “off,” the operatingmechanism handle indicates when the

breaker is “tripped” by moving to aposition midway between the extremes.This distinct trip point is particularlyadvantageous where breakers aregrouped, as in panelboard applications,because it clearly indicates the faultycircuit. The operating mechanismcontains a positive on feature. In thenormal switching operation, thehandle of the circuit breaker will notbe capable of being left readily at or nearthe off position when the main contactsare closed.

3. Arc Extinguishers

The function of the DE-ION® arc

extinguisher is to confine, divideand extinguish the arc drawn betweenopening breaker contacts. It consists ofspecially shaped steel grids isolatedfrom each other and supported by aninsulating housing. When the contactsare opened, the arc drawn induces amagnetic field in the grids, which inturn draws the arc from the contactsand into the grids. The arc is thus splitinto a series of smaller arcs and theheat generated is quickly dissipatedthrough the metal. These two actionsresult in a rapid removal of ions fromthe arc, which hastens dielectric build-up between the contacts and results in

rapid extinction of the arc.


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General Description—Trip Units006

Electronic RMS Trip Unit

General

Eaton offers the most comprehensiverange of electronic trip units in theindustry for molded-case circuit

breakers. All electronic trip units are rmssensing and can be applied from 70A upthrough 2500A. Eaton offers electronictrip units as standard for circuit breakersrated above 800A, and offers electronictrip units as optional for circuit breakers70A up through 800A.

Digitrip electronic trip units are ACdevices that employ microprocessor-based technology that provides a truerms current sensing means for propercorrelation with thermal characteristicsof conductors and equipment. Theprimary function of the Digitripelectronic trip unit is to providecircuit protection. This is achievedby analyzing the secondary currentsignals received from the circuitbreaker current sensors and initiatingtrip signals to the circuit breaker shunttrip when pre-set current levels andtime delay settings are exceeded. AllEaton electronic trip units use a higheffective sampling rate to maintainmeasurement accuracy, monitoring,and protection with nonlinear loadshaving harmonic content up to the27th order.

Electronic trip units are applied todistribution systems when high stan-dards of protection and coordination

are called for. In addition, electronictrip units can provide further enhancedfeatures such as alarming, diagnostics,system monitoring and communications.

Eaton RMS sensing trip units fall intotwo main categories:

■ Front adjustable trip units(Digitrip™ RMS 310, 310+,510, 610, 810 and 910)

■ Programmable trip units(Digitrip OPTIM™ 550 and 1050)

Front-Adjustable Trip Units

Front-adjustable trip units areelectronic trip units that have up tonine time-current setting options thatare set by switches mounted on thefront of the trip unit. The application

for front adjustable trip units wouldbe distribution systems that can becoordinated within the range ofsettings available and that do notrequire sophisticated coordinationstrategies to be applied downthrough the distribution system tosmall rated breakers.

Programmable Trip Units (OPTIM)

Programmable trip units are electronictrip units that have up to 10 time-current setting options that areprogrammed electronically by theuse of a programming device. Theapplication for programmabletrip units would be high integritydistribution systems that requiresuperior levels of system coordinationcoupled with system alarming,diagnostics and monitoring.

Rating Plugs

Rating plugs provide a means toestablish the breaker’s continuouscurrent rating. Rating plugs are color-coded and interchangeable to make iteasy to match the correct rating plug

with the correct trip unit. The samerating plug can be applied to both 50and 60 Hz distribution systems. Somerating plugs are fixed and some havean adjustable range of amperagevalues for greater flexibility. Digitrip310, 510, 610, 810 and 910 trip unitscan be supplied with either a fixed oradjustable rating plug. Digitrip 310+trip units are equipped with adjustablerating plugs. OPTIM style trip units arefurnished with fixed rating plugs buthave a programmable Long TimePickup rating to allow applicationover a range of amperage values.

Cause of Trip Indication

All OPTIM and Digitrip 510, 610, 810and 910 trip units include Cause-of-Trip indication LEDs. Breakers usingthe RMS 310+ electronic trip unithave the ability to output cause-of-tripinformation through the test port. TheCause-of-Trip LED module providestrip information via LED indication.The Digiview and PanelmountDigiview can be installed in theRMS 310+ test port to provide bothcause-of-trip information and phasecurrent through an LCD display.

Cause-of-Trip LED Module Digiview


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Table 27.1-1. The Digitrip Family of Low Voltage Electronic Trip Units

Optional features.

Additional Protection Features

Discriminator/Making Current Release

Eaton’s Digitrip RMS electronic tripunits are designed and built withsafety and reliability in mind, both toprotect the user and the equipment, as

well as to make sure the trip functionswithin its design parameters. Byproviding a discriminator circuit toDigitrip RMS 510, 610, 810 and 910 tripunits, as well as to Digitrip OPTIM 550and 1050 trip units that do not havean instantaneous setting, the user isprotected should a faulted circuit exist.The discriminator (or making currentreleases as it is often called) is set at11 times the rating plug ampere ratingand is enabled for approximately thefirst 10 cycles of current flow. Shoulda fault condition exist, the breaker willtrip with no intentional time delay onclosing, protecting the user from apotentially unsafe condition.

Instantaneous Override

In addition to a discriminator, aninstantaneous override is present inall molded-case and insulated-casecircuit breakers to provide additionalprotection for the breaker. Theinstantaneous override is factoryset nominally just below the breakerwithstand rating.

Trip Unit Overtemperature

Digitrip electronic trip units can operatereliably in ambient temperatures thatrange from –20° to 85°C. In the unlikelyevent that temperatures exceed thisambient, the trip unit has a built-inovertemperature trip to protect the trip

unit should the temperature exceedthese design parameters.

Thermal Memory

Digitrip RMS and Digitrip OPTIMelectronic trip units incorporatepowered thermal memory, i.e., theunits remember recent overcurrentevents that may have initiated the triptiming sequence, and then returned tonominal levels, halting the sequenceprior to trip initiation. In the event thatthe current levels again exceed thepickup set point within a few cycles ofthe original pickup, the unit’s memoryrecalls the previous near trip andautomatically imposes a shorterdelay time. In effect, the unit treatsmultiple time-related events as asingle continuous event therebypreventing system damage due tocumulative overheating.

As a further enhancement, the tripunits incorporate an unpoweredthermal memory feature. In the eventthat current levels cause the breakerto trip and the breaker is immediatelyreclosed, the trip unit remembers theprevious overcurrent trip and again

imposes a shorter delay time shouldan additional overcurrent occurbefore a sufficient cooldown periodhas elapsed.

Thermal memory protects thedistribution system from cumulativeoverheating caused by repeated over-

current conditions. OPTIM trip unitsallow this to be turned ON or OFF.

System Alarms

Digitrip RMS 610, 810 and 910electronic trip units incorporate ahigh load alarm capability. Set at 85%of Ir, the alarm will be initiated oncethe load current exceeds 85% for40 seconds. Once this occurs, theHILD message will flash in the displaywindow and the power/relay modulewill operate to send a remote signal.

Digitrip OPTIM electronic trip unitsalso offer a high load alarm capabilitybut with more flexibility. OPTIM tripunits have a high load alarm that canbe programmed to operate between50% and 100% of Ir.

Digitrip OPTIM electronic trip unitsincorporate a ground fault alarmcapability. Settings available for groundfault alarm are the same as for groundfault trip. Once a ground fault alarmoccurs, both local and remote signalindication is available (OPTIM 550is remote only).

RMS 310 RMS 310+ RMS 510 OPTIM 550 RMS 610 RMS 810 RMS 910 OPTIM 1050

rms sensing—5 functions—Front adjustable

rms sensing—6 functions—Front adjustable—Optional displayfor diagnosticsand loadmonitoring—Zone selectiveinterlocking—OptionalArcflashReductionMaintenanceSystem™

rms sensing—9 functions—Front adjustable—Zone selectiveinterlocking—Diagnostics

rms sensing—10 functions—Programmable—Load monitoring—Diagnostics—Zone selectiveinterlocking

—Communications

rms sensing—9 functions—Front adjustable—Zone selectiveinterlocking—Load monitoring—Diagnostics

rms sensing—9 functions—Front adjustable—Zone selectiveinterlocking—Load monitoring—Diagnostics—Communications—Power and energymonitoring

rms sensing—9 functions—Front adjustable—Zone selectiveinterlocking—Load monitoring—Diagnostics—Communications—Power and energymonitoring—Harmonics

rms sensing—10 functions—Programmable—Zone selectiveinterlocking—Load monitoring—Diagnostics—Communications—Power and energymonitoring—Harmonics


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System Diagnostics

Whenever a circuit breaker trips, it isnormally imperative that the cause oftrip be determined quickly, the faultyconditions rectified, and the breakerput back into service. Digitrip RMS

510, 610, 810 and 910, and DigitripOPTIM electronic trip units incorporatea complete package of systemsdiagnostics to meet this challenge.

Four cause-of-trip LEDs are embeddedin the front of the trip unit case,indicating that the cause-of-tripwas either a long delay, short delay,instantaneous or ground fault. Remotesignal indication for cause of trip aswell as magnitude of trip informationis also available.

Breakers using the RMS 310+electronic trip unit have the abilityto output cause-of-trip information

through the test port. The Cause-of-Trip LED module provides tripinformation via LED indication. TheDigiview and Panelmount Digiviewcan be installed to provide bothcause-of-trip information and phasecurrent through an LCD display.

Systems Monitoring

Digitrip RMS and Digitrip OPTIMelectronic trip units offer a completemenu of monitoring capability toinclude current, power and energy,power factor, power quality harmonics,and other related parameters with ahigh level of accuracy.

Digital Display

Digitrip RMS 610, 810 and 910 havea large, easy-to-read four-digit alpha-numeric display mounted on the tripunit. The display is supported by LEDsthat indicate which parameter is beingdisplayed along with the unit the valueis displayed in, e.g., kA and so on.

Current Monitoring

Digitrip RMS 610, 810 and 910 trip unitsare capable of monitoring currentsin individual phases (A, B, C) as wellas ground currents. Digitrip OPTIM550 and 1050 trip units are capable

of monitoring currents in individualphases (A, B, C) as well as neutraland ground currents.

Values are displayed in the digitaldisplay window in kA. Accuracy of thecurrent monitored values is ±2% of fullscale sensor rating.

Breakers using the Digitrip 310+electronic trip unit have the abilityto output phase current monitoringinformation through the test port. TheDigiview or Panelmount Digiview canbe installed to provide phase currentthrough an LCD display.

For current and voltage monitoringwith 0.5% accuracy of reading that canbe used with thermal-magnetic orelectronic trip units, refer to the PowerMonitoring/Metering Module (PM3)on Page 27.4-41.

Power and Energy Monitoring

For the trip unit to calculate truepower and energy values, a PotentialTransformer Module (PTM) is required.This PTM is mounted internally(R-Frame and larger) or externally(N-Frame or smaller) to the breaker,and provides voltage to the trip unit.

Digitrip RMS 810 and 910 trip units

are capable of monitoring peak powerdemand, present power demand, andreverse power flow in MW. Addition-ally, both forward and reverse energyconsumption in MWh can be moni-tored. Digitrip OPTIM 1050 trip unitscan also monitor the same power andenergy parameters, but the units aredisplayed in kW and kWh.

The accuracy of power monitoredvalues is ±4% of full scale sensor/ frame rating.

The accuracy of energy monitoredvalues is ±5% of full scale sensor/ frame rating.

Both the RMS 910 and OPTIM 1050report power factor. Digitrip RMS 910trip units have the additional capabilityof monitoring line-to-line voltage.

For Real Power and Reactive Powermonitoring with ANSI C12.1 revenueclass accuracy that can be used withthermal-magnetic or electronic tripunits, refer to the Power Monitoring/ Metering Module (PM3) onPage 27.4-41.

Harmonics Monitoring

Digitrip RMS 910 and Digitrip OPTIM1050 trip units are capable of monitor-

ing values of current harmonics.Percentage of total harmonic contentcan be monitored for each level ofharmonic content up to the 27thharmonic. Additionally, a totalharmonic distortion (THD) value canbe calculated and displayed providingthe user with total system currentharmonic monitoring capability.


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Time-Current Curve Shaping

Figure 27.1-1. Time-Current Curve Shaping

Note: See selection guide charts foravailability of adjustments.

Long Delay (L)

1. Long Delay PickupDetermines the continuousampere rating of the breaker.

2. Long Delay TimeDetermines the amount of timethe breaker will carry a low leveloverload before tripping.

a. I2t ResponseI2t in: For coordination with other circuit breakers with electronictrip devices and for coordinationwith thermal-magneticcircuit breakers.

b. I4t ResponseI4t in: For coordination withfuses and upstream trans-former damage curves.

7B

7A

6

T i m e

5

1

4B

4A

2A

2B2

3

Current in Multiples

4

7

Short Delay (S)

3. Short Delay PickupDetermines or sets the levelof fault current at which theshort-time trip delay countdownis actuated.

4. Short DelaySets the amount of time the breakerwill carry both a low level and highfault currents before tripping.

a. Flat ResponseI2t out: For coordination withother circuit breakers withelectronic trip devices.

b. I2t ResponseI2t in: For coordination withfuses and thermal-magneticbreakers.

Instantaneous (I)

5. Instantaneous Pickup

Determines the level of faultcurrent that will actuate a tripwith no time delay.

Ground Fault (G)

6. Ground Fault PickupDetermines the level of faultcurrent at which the ground faulttrip delay countdown is actuated.

7. Ground Fault DelayDetermines the amount of timethe breaker will carry a groundfault before tripping.

a. Flat ResponseI2t out: For coordination with

other circuit breakers withelectronic ground fault settings.

b. I2t ResponseI2t in: For coordination withzero sequence ground faultrelays, fuses and thermal-magnetic breakers.

Curve Shaping

Eaton Digitrip RMS 310 trip units areavailable with up to five phase andground adjustments on the front of thetrip unit. Digitrip RMS 310+ trip unitsare available with up to six phase and

ground adjustments on the front of thetrip unit. Selective system coordinationwith both upstream and downstreamdevices can be achieved to provide aneconomic solution for less sophisticateddistribution systems.

For more sophisticated selectivecoordination systems Digitrip RMS510, 610, 810 and 910 trip units areavailable with up to nine curve shapingchoices via switches on the front ofthe unit. Curve shaping flexibility isprovided by dependent long and shortdelay adjustments that are based oncontinuous amperes (Ir) selection.

Digitrip OPTIM 550 and 1050 tripunits offer programmable curveshaping via 10 curve shaping choicesthat are programmed electronicallyinto the trip unit. OPTIM also offersvirtual infinite settings to allow theuser to optimize coordination for aselectively coordinated distributionsystem. In addition, time-current setpoints can be downloaded via acommunication system from a centralpersonal computer. Digitrip OPTIM isnormally applied to systems wheresystem integrity is very important.


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Zone Selective InterlockingZone selective interlocking capabilitiesare available with Digitrip RMS 310+510, 610, 810 and 910 trip units aswell as Digitrip OPTIM 550 and1050 trip units.

Note: Optional accessory on the OPTIM 550.

Zone selective interlocking providesincreased system protection and canreduce arc flash risk by allowing thebreaker closest to the fault to tripwithout any preset time delays. This isachieved by setting up the distributionsystem as shown in Figure 27.1-2.The hardwired connection betweenthe trip units sends a restraining signalupstream, allowing the breaker closestto the fault to act instantaneously. Zoneselective interlocking reduces stresson the distribution system and can

reduce arc flash risk by isolating faultswithout time delays.

Figure 27.1-2. Zone Selective Interlocking

Fault 1

There are no interlocking signals.The main breaker trip unit will initiatethe trip instantaneously.

Fault 2

The feeder breaker trip unit will initiatethe trip instantaneously to clear thefault; and Zone 2 will send an inter-locking signal to the Zone 1 trip unit.The Zone 1 trip unit will begin to timeout, and in the event that the feederbreaker in Zone 2 would not clearthe fault, the main breaker in Zone 1will clear the fault in 0.5 seconds.

Fault 3

The branch breaker trip unit will initiatethe trip instantaneously to clear thefault; and Zone 3 will send an interlock-ing signal to the Zone 2 trip unit; andZone 2 will send an interlocking signalto Zone 1.

Zone 1 and Zone 2 trip units willbegin to time out, and in the eventthat the branch breaker in Zone 3would not clear the fault, the feederbreaker in Zone 2 will clear the fault

in 0.3 seconds. Similarly, in the eventthat the feeder breaker in Zone 2would not clear the fault, the mainbreaker in Zone 1 will clear the faultin 0.5 seconds.

Zone 1

Zone 2

Zone 3

Fault 1

Fault 2

Fault 3

Load

BreakerNumber 1

BreakerNumber 2

BreakerNumber 3

Ground Fault Setting:300A PickupNo Time Delay

Zone SelectiveInterlocking Wiring

Ground Fault Setting:600A Pickup0.3 Seconds Time Delay

Ground Fault Setting:1200A Pickup0.5 Seconds Time Delay


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Accessories and Modifications011

Internal AccessoriesNote: For a complete listing of availableexternal accessories, see Volume 4—CircuitProtection Catalog, CA08100005E, Section 25.

All internal accessories are of the

plug-in type and are listed for fieldinstallation under UL File E64983.Internal accessories for sealed circuitbreakers are listed under UL File E7819for factory installation only. Theavailable plug-in accessories includethe following:

■ Alarm (signal)/lockout switch

■ Auxiliary switch

■ Shunt trip

■ Low energy shunt trip

■ Undervoltage release mechanism

Typical Internal Plug-in Accessory Installedin K-Frame Circuit Breaker

Different accessory wiring options areavailable to satisfy most circuit breakermounting applications. The standardwiring configuration is pigtail leadsexiting the rear of the base directlybehind the accessory. Optionalconfigurations include a terminal

block mounted on the same side of thebase as the accessory, leads exiting theside of the base where the accessoryis mounted, and leads exiting the rearof the base on the side opposite theaccessory. If accessory leads longerthan 18.00 inches (457.2 mm) arerequired, side-mounted terminalblocks should be used.

Alarm (Signal)/Lockout Switch

The alarm (signal)/lockout switchmonitors circuit breaker trip status andprovides remote signaling and inter-locking capabilities when the circuitbreaker trips. For two-, three- and

four-pole circuit breakers, the alarm(signal)/lockout switch consists of oneor two SPDT switches assembled to aplug-in module mounted in retainingslots in the top of the trip unit. TheSPDT switch contacts are identified asmake and break contacts. When thecircuit breaker trips, the make contactcloses and the break contact opens.

Alarm (Signal)/Lockout Switch

Auxiliary Switch

The auxiliary switch provides circuitbreaker contact status informationby monitoring the position of themolded crossbar containing themoving contact arms. The auxiliaryswitch is used for remote signalingand interlocking purposes, andconsists of one or two SPDT switches

assembled to a plug-in modulemounted in retaining slots in the topof the trip unit. Each SPDT switch hasone “a” and one “b” contact. Whenthe circuit breaker contacts are open,the ”a“ contact is open and the “b”contact is closed.

Auxiliary Switch

Shunt Trip

The shunt trip provides remote controlled tripping of the circuit breaker. The shunttrip consists of an intermittent ratedsolenoid with a tripping plunger anda cutoff switch assembled to a plug-in

module. When required for groundfault protection applications, certainAC rated shunt trips are suitable foroperation at 55% of rated voltage.

Available in most AC and DC voltages.

Note: Approximate unlatching time—6 milliseconds. Approximate totalcircuit breaker contact opening time—18 milliseconds. Endurance—4000 electricaloperations plus 1000 mechanical opera-tions. Supply voltages suitable for use withClass 1 GFP devices. Marking label includedwith accessory kits.

Shunt Trip

OPTIM Communications Kit

Eaton’s OPTIM Communications Kitprovides the option to field installPowerNet communications into a K-, L-

or N-Frame OPTIM 550 breaker. OPTIM1050 trip units come equipped withcommunications as standard.

OPTIM Communications Kit

Make

Break

a

b

STa


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Accessories and Modifications012

Low Energy Shunt Trip

Low energy shunt trip devices aredesigned to operate from low energyoutput signals from dedicated currentsensors typically applied in groundfault protection schemes. However,

with a proper control voltage source,they may be applied in place ofconventional trip devices for specialapplications. Flux paths surroundingpermanent magnets used in the shunttrip assembly hold a charged springpoised in readiness to operate thecircuit breaker trip mechanism. Whena 100 microfarad capacitor charged to28 Vdc is discharged through the shunttrip coil, the resultant flux opposes thepermanent magnet flux field, whichreleases the stored energy in thespring to trip the circuit breaker. Asthe circuit breaker resets, the resetarm is actuated by the circuit breaker

handle, resetting the shunt trip. Theplug-in module is mounted in retainingslots in the top of the trip unit. Coil isintermittent-rated only. Cutoff provisionsrequired in control circuit.

Low Energy Shunt Trip

Undervoltage Release MechanismThe undervoltage release mechanismmonitors a voltage (typically a linevoltage) and trips the circuit breakerwhen the voltage falls to between 70and 35% of the solenoid coil rating.

Note: Undervoltage release mechanismaccessories are not designed for, andshould not be used as, circuit interlocks.

The undervoltage release mechanismconsists of a continuous ratedsolenoid with a plunger and trippinglever assembled to a plug-in module.

The tab on the tripping lever resets

the undervoltage release mechanismwhen normal voltage has beenrestored and the circuit breaker handleis moved to the reset (OFF) position.

With no voltage applied to the under-voltage release mechanism, the circuitbreaker contacts will not touch when aclosing operation is attempted.

Undervoltage Release Mechanism

External AccessoriesNote: For a complete listing of availableexternal accessories, see Volume 4—CircuitProtection Catalog, CA08100005E, Section 25.

Non-Padlockable Handle Block

The nonlockable handle block secures

the circuit breaker handle in either theON or OFF position. (Trip-free operationallows the circuit breaker to trip whenthe handle block holds the circuitbreaker handle in the ON position.)The device is positioned over the circuitbreaker handle and secured by a set-screw to deter accidental operationof the circuit breaker handle. (Fieldinstallation only.)

Non-Padlockable Handle Block

Padlockable Handle Lock HaspThe padlockable handle lock haspallows the handle to be locked in theON or OFF position. (Trip-free operationallows the circuit breaker to trip whenthe handle lock holds the circuit breakerhandle in the ON position.) The haspmounts on the circuit breaker coverwithin the trimline. The cover ispredrilled on both sides of theoperating handle so that the haspcan be mounted on either side of thehandle. The hasp will accommodateup to three padlocks with 1/4-inch(6.4 mm) shackles. One per circuitbreaker. (Field installation only.)

Padlockable Handle Lock Hasp

Key Interlock Kit (Lock Not Included)

The key interlock is used to externallylock the circuit breaker handle in theOFF position. When the key interlock islocked, an extended deadbolt blocksmovement of the circuit breaker

handle. Uniquely coded keys areremovable only with the deadboltextended. Each coded key controls agroup of circuit breakers for a givenspecific customer installation.

The key interlock assembly consistsof a mounting kit and a purchasersupplied deadbolt lock. The mountingkit comprises a mounting plate, whichis secured to the circuit breaker coverin either the left- or right-pole position;key interlock mounting hardware; anda wire seal. Specific mounting kits arerequired for individual key interlocktypes. (Field installation only.)

Key Interlock Kit

Padlockable Handle Block

The device is positioned in the coveropening to prevent handle movement.Will accommodate one 5/16-inch(8.0 mm) padlock.

Padlockable Handle Block

ST

LE

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CA08104001E For more information visit: www.eaton.com/consultants

27December 2013


Sheet 27


Molded-Case Switches013

Molded-Case SwitchesEaton molded-case switches (MCS)are UL 489 devices that don’t havethermal protection, but do have a self-protecting high-magnetic trip setting.Molded-case switches are applied

when a compact high-capacitydisconnect device is necessary.Accessories that can be installed inmolded-case circuit breakers are alsoavailable for molded-case switches.The most common application for amolded-case switch would be as amain disconnect for a panelboardor a loadcenter. Available from 100 to2500A, molded-case switches providea compact high-capacity disconnectdevice along with the added benefitsof a molded-case circuit breakerwithout the thermal protection.

It provides no overcurrent protection,

overload or low level fault. The MCSis equipped with a high instantaneousmagnetic fixed trip unit. The fixedmagnetic trip is factory preset tointerrupt high fault currents at orabove its preset level. MCS is selfprotecting within its withstand rating.See Table 27.2-1.

Motor Circuit Protectors

Application flexibility of Eaton motorcircuit protectors (Type GMCP/HMCP/ HMCPE) is enhanced by the higherinterrupting ratings and current limitingcharacteristics designed into the line.These devices are available from

3–1200A in 63, 100, 150, 250, 400, 600,800 and 1200A frame sizes.

The motor circuit protectors aredesigned for application in individualmotor circuits in combination motorstarter units. Motor circuit protectorsoperate on the magnetic principle witha current sensing element in each poleto provide short-circuit protection.

The motor circuit protector designpermits the most effective protectionpossible against low-level faults whileoffering circuit breaker convenience,quick-make quick-break action,deadfront safety and preventionof single phasing.

The GMCP and HMCPE are 480Vdevices rated between 3–100A. TheHMCP is a 600V device available in fiveframes and rated between 3–1200A.The MCP is designed to comply withthe applicable requirements ofUnderwriters Laboratories StandardUL 489, Canadian StandardsAssociation Standard C22.2 No. 5,and International ElectrotechnicalCommission RecommendationsIEC 157-1.

An innovative design of internalcomponents allows higher MCP-startercombination interrupting ratings.The MCP is marked to permit properelectrical application within theassigned equipment ratings.

The MCP is a recognized component(UL File E7819) and complies with theapplicable requirements of Underwriters Laboratories Standard UL 489. It is alsodesigned to comply with the applicablerequirements of Canadian StandardsAssociation Standard C22.2 No. 5,and International ElectrotechnicalCommission RecommendationsIEC 157-1. The interrupting ratingis defined on the assembledequipment nameplate.

Table 27.2-1. Molded-Case Switch Short-Circuit Current Ratings at 60 Hz Only(Maximum Fault Current at Which Device can be Applied in kAIC)

MCSFrame AmpereRating Short-Circuit Current Rating240V 480V 600V 250 Vdc

GDEHDFD

100 100 150

65 18 65

221435

——18

101010

HFDJDHJD

150 250 250

100 65100

653565

251825

221022

DKKDHKD

400 400 400

65 65100

—3565

—2535

101022

LDHLDMDL

600 600 800

65100 65

356550

253525

222522

HMDLNDHND

80012001200

100 65100

655065

352535

25——

RDEGKJGK

2000 125 250

125100100

656565

50—35

—4242

LGKLGKNGKRGK

400 60012002000

100100100125

65656565

35353550

4242——


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Selection Data—Motor Circuit Protectors014

Motor ProtectionIn line with 2008 NEC 430.6(A)circuit breaker, HMCP and fuse ratingselections are based on full loadcurrents for induction motors runningat speeds normal for belted motors

and motors with normal torquecharacteristics using data taken fromNEC Table 430.250 (three-phase).Actual motor nameplate ratings willbe used for selecting motor runningoverload protection. Motors builtspecial for low speeds, high torquecharacteristics, special startingconditions and applications willrequire other considerations asdefined in the application sectionof the NEC.

These additional considerations mayrequire the use of a higher rated HMCP,or at least one with higher magnetic

pickup settings.Circuit breaker, HMCP and fuseampere rating selections are inline with maximum rules given inNEC 430.52 and Table 430.250. Basedon known characteristics of Eatontype breakers, specific units arerecommended. The current ratingsare no more than the maximum limitsset by the NEC rules for motors withcode letters F to V or without codeletters. Motors with lower code letterswill require further considerations.

In general, these selections werebased on:

1. Ambient—Outside enclosure notmore than 40°C (104°F).

2. Motor starting—Infrequentstarting, stopping or reversing.

3. Locked rotor—Maximum 6 timesmotor FLA.

4. Locked rotor—Maximum 6 timesmotor FLA.

Type HMCP motor circuit protectormay not be set more than 1300% ofthe motor full-load current to complywith NEC 430.52 (except for NEMADesign B energy efficient motors,

which can be set up to 1700%).

Circuit breaker selections are basedon types with standard interruptingratings. Higher interrupting ratingtypes may be required to satisfyspecific system applicationrequirements.

For motor full load currents of 208Vand 200V, increase the corresponding230V motor values by 10 and 15%respectively.

Table 27.2-2. Motor Circuit Protector (MCP), Circuit Breaker and Fusible Switch Selection Guide

Horsepower Full LoadAmperes(NEC) FLA

Fuse Size NEC 430.52MaximumAmperes

Recommended Eaton

CircuitBreaker

Motor CircuitProtector Type HMCP

Time Delay Non-Time Delay Amperes Amperes Adj. Range

230V, Three-Phase

1 1-1/2 2 3

3.6 5.2 6.8 9.6

10 10 15 20

15 20 25 30

15 15 15 20

7 15 15 30

21–70 45–150 45–150 90–300

5 7-1/2 10 15

15.2 22 28 42

30 40 50 80

50 70 90 150

30 50 60 90

30 50 50 70

90–300 150–500 150–500 210–700

20 25 30 40

54 68 80104

100 125 150 200

175 225 250 350

100125150150

100150150150

300–1000 450–1500 450–1500 750–2500

50 60 75100

130154192248

250 300 350 450

400 500 600 800

200225300400

150250400400

750–25001250–25002000–40002000–4000

125

150200

312

360480

600

7001000

1000

12001600

500

600700

600

600600

1800–6000

1800–60001800–6000

460V, Three-Phase

1 1-1/2 2 3

1.8 2.6 3.4 4.8

6 6 6 10

6 10 15 15

15 15 15 15

7 7 7 15

21–70 21–70 21–70 45–150

5 7-1/2 10 15

7.6 11 14 21

15 20 25 40

25 35 45 70

15 25 35 45

15 30 30 50

45–150 90–300 90–300 150–500

20 25 30 40

27 34 40 52

50 60 70 100

90 110 125 175

50 70 70100

50 70100100

150–500 210–700 300–1000 300–1000

50 60

75100

65 77

96124

125 150

175 225

200 150

300 400

110125

150175

150150

150150

450–1500 750–2500

750–2500 750–2500

125150200

156180240

300 350 450

500 600 800

225250350

250400400

1250–25002000–40002000–4000

575V, Three-Phase

1 1-1/2 2 3

1.4 2.1 2.7 3.9

3 6 6 10

6 10 10 15

15 15 15 15

3 7 7 7

9–30 21–70 21–70 21–70

5 7-1/2 10 15

6.1 9 11 17

15 20 20 30

20 30 35 60

15 20 25 40

15 15 30 30

45–150 45–150 90–300 90–300

20 25 30 40

22 27 32 41

40 50 60

80

70 90 100 125

50 60 60 80

50 50 50

100

150–500 150–500 150–500 300–1000

50 60 75100

52 62 77 99

100 110 150 175

175 200 250 300

100125150175

100150150150

300–1000 750–2500 750–2500 750–2500

125150200

125144192

225 300 350

400 450 600

200225300

250250400

1250–25001250–25002000–4000


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Sheet 27


Selection Data—Current Limiting Circuit Breakers015

Current Limiting Circuit BreakersEaton offers one of the most completelines of both fusible and non-fusedcurrent limiting breakers, and add-oncurrent limiting modules in theindustry. The industrial breakers are

available in current limiting versionswith interrupting capacities up to200 kA at 480V without fuses in thesame physical size as standard andhigh interrupting capacity breakers.Eaton also manufactures both fusedand non-fused current limiting deviceswith interrupting capacities up to200 kA at 600 Vac. See Section 27.4 forcomplete selection data for currentlimiting circuit breakers and add-oncurrent limiting modules.

The current limiting breakers use areverse loop stationary contact. Whencurrent is flowing through the contacts

of these breakers, the positions of thereverse loop and moving contact arminduce opposing magnetic fields. Theresulting flux lines cause rapid contactblow-apart under these conditions,resulting in very high interruptingcapacities and provide currentlimiting characteristics.

Current limiting breakers are availablefrom 15–2500A and have an interruptingrating up to 200 kA at 480V. Thesebreakers are most commonly appliedwhen very high fault levels are avail-able and in series rating applicationswhere the current limiting capabilityof these breakers are used upstream

in series combinations.

Circuit breakers 600A and below thatare current limiting have frame catalognumbers that end with the letter “C.”For example, the F-Frame model that iscurrent limiting has a catalog numberFDC. In accordance with UL circuitbreaker marking requirements, thenameplate on the breaker is alsolabeled “current limiting.”

Current Limit-R Breakers—Non-Fused

FCL Current Limit-R Breaker

The Current Limit-R® molded-casecircuit breaker was developed withinterrupting ratings up to 200,000A at480 Vac to provide complete systemprotection against faults, including:

1. Overloads, by using inverse timecurrent tripping characteristics.

2. Low-level short-circuits, by usinginstantaneous and/or short-timedelay tripping characteristics.

3. High-level short-circuits, by usingultra high-speed, blow-apart,current limiting contacts.

Current Limit-R circuit breakers canbe used in series with Eaton standardmolded-case circuit breakers withlisted interrupting ratings as low as10,000A in systems capable of deliver-ing fault currents as high as 200,000A.The excellent current limiting propertiesof Current Limit-R breakers completelyprotect all Eaton downstream seriescircuit breakers applied within theirvoltage ratings.

The high level current-limiting action isachieved by the use of special design,blow-apart contacts. The openingspeed of the contacts is amplified bythe repulsion force in the slot motor toeffectively separate the contacts under

high level fault conditions in less thanone millisecond. The rapid rise of arcvoltage introduces impedance into thesystem, thus limiting the amount of theotherwise available fault current.

Current Limit-R current limiting circuitbreakers incorporate all the advantagesand features of conventional molded-case circuit breakers. They are availablein two- and three-pole versions intwo physical frame sizes and threecontinuous current frame ratings.

Type FCL has a maximum continuouscurrent frame rating of 100A. It isequipped with a conventional, non-

interchangeable, thermal-magnetic-type trip unit with individual ampereratings. The Type LCL is availablewith frames having maximumcontinuous current ratings of either250 or 400A. Overload and low levelshort-circuit protection is provided bya SELTRONIC™ electronic trip unit thatuses the individual rating plug conceptfor determining the continuousrating of the breaker. Rating plugsare available with either fixed oradjustable ampere ratings.


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Selection Data—Current Limiting Circuit Breakers016

TRI-PAC Fused Current Limiting Breakers

LA TRI-PAC Breaker

The increase in demand for electricalpower in modern commercial andindustrial buildings has resulted inelectrical services becoming substan-tially larger. In some low voltage

distribution systems, available short-circuit currents can exceed 100,000symmetrical rms amperes. Faultcurrents of this intensity may exceedthe interrupting ratings of molded-casebreakers. As a result, larger expensivecircuit interrupting devices that couldwithstand the thermal and magneticstresses associated with currents ofthis value have had to be used. Highinterrupting capacity current limitingdevices have been developed thatwill restrict short-circuit current. Ifapplied correctly, they may be used inconjunction with molded-case circuitbreakers to provide adequate and

economical protection.The TRI-PAC® breaker was developedfor this application and so namedbecause it affords TRIple-PACkageprotection with (1) time delay thermaltrip, (2) instantaneous magnetic tripand (3) current limiting protection,combined and coordinated in a compactand economical device. These protec-tive actions are so coordinated thatovercurrents and low magnitude faultsare cleared by the thermal action;normal short circuits are cleared bythe magnetic action; and abnormalshort circuits, above an establishedvalue, are cleared by the currentlimiting device. Thus, unless a severeshort-circuit occurs, the current limiteris unaffected and its replacement isheld to a minimum.

TRI-PAC breakers are available in ratingsfrom 15–1600A and have a UL listedinterrupting capacity of 200,000Aat up to 600 Vac and also have aninterrupting capacity of 100,000Aat up to 250 Vdc.

The TRI-PAC breaker offers all of theadvantages of the economical molded-case breaker and the current limiteris retained, while the disadvantagesof separately mounted devicesare eliminated.

Add-on Current Limiting Modules

Current Limiting Add-On Modules

The current limiting breaker modulesuse a reverse loop stationary contactarm. When high short-circuit current isflowing through the contacts of thesemodules, the positions of the reverse

loop and moving contact arm induceopposing magnetic fields. The resultingflux lines cause rapid contact blow-apartunder fault conditions, resulting invery high interrupting capacities andproviding current limiting characteris-tics. Current limiting breaker modulesin combination with select Series Cand Series G breakers, are availablewith interrupting ratings up to 200 kAat 600 Vac.

The combination of the current limit-ing breaker or HMCP and the currentlimiter module provides the followingsystem protection:

■ Overloads, by using inverse timecurrent tripping characteristics of

the molded-case circuit breaker■ Low-level short circuits, by using

instantaneous and/or short-timedelay tripping characteristics of themolded-case circuit breaker

■ High-level short circuits, by usingultra-high-speed, blow-apartcontacts of the current limitingmodule in series with the circuitbreaker contacts. The high-levelcurrent limiting action is achievedby the use of special design, blow-apart contacts. The opening speedof the contacts is amplifed by therepulsion force in the slot motor and

reverse loop stationary contact armto effectively separate the contactsunder high-level fault conditions inless than 1 millisecond. The rapidrise of arc voltage introducesimpedance into the system, thuslimiting the amount of the otherwiseavailable fault current


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Sheet 27


Application Information—100% Rated Circuit Breakers017

100% Rated Circuit Breakers100% rated circuit breakers are testedinside a minimum size enclosure toUL 489 for application at 100% of thebreaker’s continuous current rating.100% rated circuit breakers are equipped

with electronic trip units and appliedwith 90ºC cable rated at 75ºC ampacity.To apply 100% rated breakers inswitchboards and panelboards,additional tests are required to meetUL 67 and UL 891. Eaton molded-casecircuit breaker frames K-, L-, N-, MDLand R-, 70–2000A, can be applied at100% of their rated continuous currentas long as the breaker is installed in itsminimum size enclosure, includingventilation. 100% rated breakers areapplied to distribution system to provideinstallation cost savings. The amountof savings that can be realized isdependent on the application.

Figure 27.2-1. Breaker Nameplate

A 100% rated breaker receives its UL listingbased on tests conducted in a minimumsize enclosure with minimum ventilation(if required) and minimum cable sizes,as stated on this nameplate example.

The amount of protection designedinto a distribution system is often basedon economics. However, each projectshould be furnished with a reliabledistribution system that delivers themost effective protection possible foreach investment dollar.

Reliable and economic system design

can be usually achieved with Eaton’scircuit breakers that are UL listed forapplication at 100% of their ratings—instead of standard breakers that inactual use are applied at 80% of theirframe ratings in an enclosure.

The concept between a system designusing standard breakers and thatusing 100% rated breakers isuncomplicated—but there are noshortcut methods for determining

which design (and devices) is thebest choice for a given system. Goodengineering practice requires a carefulsystem analysis beginning with thelowest feeder and concluding withthe main device.

Also included in the system analysismust be all present and futurefactors that could affect the sizeand/or quantity of the breakers andassociated hardware, such as switch-board bus, busway, cable and conduit.Other factors to consider are loads(continuous and noncontinuous) andsystem expansions and transformerswith provisions for forced air cooling.

The NEC

The rules and intent of the NationalElectrical Code governing the use ofstandard or 100% rated breakers mustbe understood before recommending

or applying such devices.

Section 210.20(A) Continuous andNoncontinuous Loads of the NationalElectrical Code addresses differencesbetween applications of standard ratedbreakers and 100% rated breakers.(Significant sections are in boldface type.)

Figure 27.2-2. NEC Reference

Section 210.20(A) covers standardbreakers, and the exception 100%rated breakers. NEC Section 210.20(A)and the Section 210.20(A) exceptioncan be expressed by these formulas:

Standard 80% Rated Design

Noncontinuous Load +125% of the Continuous Load= Total Minimum Load

Special 100% Rated DesignNoncontinuous Load +Continuous Load= Total Minimum Load

The necessity for these NEC require-ments results from circuit breakertesting procedures.

A molded-case circuit breaker istested in open air to verify its name-plate ampere rating. The nameplatespecifies a value of current the circuit

breaker is rated to carry continuouslywithout tripping within specificoperating temperature guidelines.

In most instances, a breaker is appliedin an enclosure and performance couldbe adversely affected by slow heatdissipation and temperature rise. Thesefactors must be considered regardingthe ability of the breaker to complywith its nameplate ampere rating.

Testing Conditions and Operating Conditions

There are distinct differences betweenthese conditions that are addressed inNEC Section 210.20(A) by introducingan overcurrent device and associatedhardware sizing factor. The sizingfactor ensures reliable equipmentperformance under realistic condi-tions. Section 210.20(A) is the key tomaking the best system design choice.

For feeders, Section 215.2(A)addresses the rating of all overcurrentdevices that have been tested in openair but are applied in an enclosure. Thethermal response of an overcurrentdevice applied in an enclosure willusually be faster than in open air,thus dictating the 125% requirement.

The exception allows for properly tested

and listed overcurrent devices to beapplied at 100% of their nameplate rating.

Breaker

Nameplate

Example

100%

Application–

enclosure

and

wire ampacity

requirements.

“Where a feeder supplies continu-ous loads or any combination ofcontinuous and noncontinuousloads, the rating of the overcur-rent device shall not be less thanthe noncontinuous load plus

125% of the continuous load.”

The minimum circuit conductorsize without the application of anyampacity adjustment or correctionfactors shall have an allowableampacity equal to or greater thanthe noncontinuous load plus125% of the continuous load.

“Exception: Where the assemblyincluding the overcurrent devicesprotecting the feeder(s) are listedfor operation at 100% of theirrating, neither the ampere ratingof the overcurrent device nor theampacity of the feeder conductorsshall be less than the sum ofthe continuous load plus thenoncontinuous load.”

Note: A continuous load as definedby NEC Article 100 is “a load wherethe maximum current is expected tocontinue for 3 hours or more.”


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There is a Difference Between 100% RatedBreakers and 100% Rated Assemblies

Special attention should be givento the word “assembly” in the NECException. Normally, an assemblyis listed for 100% operation only

after being successfully tested asan assembly per UL requirements.

For an assembly to receive a 100%rated UL listing, it must be testedseparately by UL project engineers.Panelboards are tested to UL 67,switchboards tested to UL 891.

Installing 100% rated breakers inan assembly does not automaticallymake it acceptable for a 100% rating.

Figure 27.2-3. Conductor Requirements

Table 27.2-3. The Application—These Examples Illustrate the Cost Savings when the 100% Rated Approach is Used

Selection of either a 100% rated design or standard design must result from a system analysis beginning with the lowest feeder and concluding withthe system’s main device. For these system examples, assume that all assembly testing has been successfully completed and either the 100% rateddesign or standard design can be selected. Each system is hypothetical and either approach will meet safety requirements. Loads were arbitrarilyselected. The load table includes the calculations for minimum total loads in conformance with NEC Section 210.20(A).

Table 27.2-4. Standard 80% Rated Design

(Noncontinuous Load) + (125%) (Continuous Load) per NEC Section 210.20(A).

Nearest standard size, not less than calculated value.

The NEC allowsthe breaker to berated at 100% ofits frame size inan assembly,provided that90°C wire isapplied at the75°C ampacity.

90°C Wire

90°C Wire

A visual comparison of breaker, bus and cable sizes in the Three-Phase Distribution Systemexamples (line diagrams) reveals how a 100% rated system design can provide cost savings.

Load Feeder #1 Feeder #2 Feeder #3 Main Description

Continuous 400A 800A 0 1200A Three-phase distributionSystem line diagramsNoncontinuous 200A 0 1000 1200A

Noncontinuous Load + 125% of the Continuous Load = Total Minimum Load Line Diagram

Description Feeder No. 1 Feeder No. 2 Feeder No. 3 Main

Calculationper NECof minimumtotal load

200 + (1.25) (400)=700A

0 + (1.25) (800)=1000A

600 + 0 = 600A 2250A

Breakerframe (F)trip (T)rating

(F) (T)800A /700A

(F) (T)1200A /1000A

(F) (T)600A/600A

(F) (T)2500A /2500A

Bus/cablerating

800A 1000A 600A 2500A

2500A F2500A T

800A F700A T

1200A F1000A T

600A F600A T

2500A Bus

Pnlbd. 600A BusMCC 800A Bus

2–350 kcmil,Cu per phase



1000A Busway

Feeder#1

Feeder#2

Feeder#3


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Table 27.2-5. Standard 100% Rated Design

(Noncontinuous Load) + (Continuous Load) per NEC Section 210.20(A) Exception. Sum of all NEC calculated minimum feeder loads.

Table 27.2-6. The Result—Savings in Both Switchboard and Cable Costs

Table 27.2-7. Available 100% Rated Circuit Breakers

Thermal-magnetic LG requires venting 7.00 square inches above and 7.00 square inches below on the front face of enclosure. Use with 9.00-inch (228.6 mm) tee connector.

Noncontinuous Load + Continuous Load = Total Minimum Load Line Diagram

Description Feeder No. 1 Feeder No. 2 Feeder No. 3 Main

Calculationper NECof minimum

total load

200 + 400 = 600A 0 + 800 = 800A 600 + 0 = 600A 2000A

Breakerframe (F)trip (T)rating

(F) (T)600A/600A

(F) (T)800A/800A

(F) (T)600A/600A

(F) (T)2000A/2000A

Bus/cablerating

600A 800A 600A 2000A

Design Minimum Total Load

(Amperes)

Potential System

Savings

Standard 700 1000 600 2250 100% rated breaker systemscan potentially representsignificant economicadvantages:In lower rated and sizedbreakers, less cable andsignificant reductions inequipment floor and wallspace. These savings can berealized when the results ofa systems analysis favor the100% rated design approach.

100% rated 600 800 600 2000

Results The standard designrequires higher rated,more expensive breakerand bus. Although theminimum total load is700A, most breakers andhardware are availableonly in standard sizesrequiring even moreexpensive “neareststandard size” breakersand hardware.

Dramatic economicadvantages areachieved by usingthe 100% rateddesign. Substantialsavings result fromusing an 800Abusway and signifi-cant savings arealso provided bythe smaller breakerframe and cable size.

Calculations indicateeither approachresults in the samesize breaker and hard-ware. A 100% ratedbreaker would bemore expensivealthough the finaldecision could reston whether or notfuture load growthis anticipated.

The 100% approach resultsin the same frame sizebreaker with a savings inconductor material cost.Additionally, Eaton offers a2000A frame 100%-ratedbreaker, which is lessexpensive than the 2500Aframe 80%-rated.

Frames Ratingat 480V

TripUnits

JG-Frame 50/100/250AMinimum enclosure size26.00 x 18.00 x 8.00 in (660.4 x 457.2 x 203.2 mm)

JGE-C 25 kAJGS-C 35 kAJGH-C 65 kAJGC-C 100 kA

Thermal-magnetic, Digitrip 310+

K-Frame 125/250/400AMinimum enclosure size24.00 x 15.00 x 6.00 in (609.6 x 381.0 x 152.4 mm)

CKD 35 kACHKD 65 kA

Digitrip 310+ (125A, 250A and 400A)

LG-Frame 250/400/600AMinimum enclosure size with ventilation28.00 x 19.00 x 8.00 in (711.2 x 482.6 x 203.2 mm)

LGE-C 35 kALGS-C 50 kALGH-C 65 kA

Thermal-magnetic, Digitrip 310+

L-Frame 125/250/400/600AMinimum enclosure size with ventilation24.00 x 15.00 x 6.00 in (609.6 x 381.0 x 152.4 mm)

CLD 35 kACHLD 65 kACLDC 100 kA

Digitrip 310, Digitrip OPTIM

M-Frame 800A

Minimum enclosure size with ventilation42.00 x 18.00 x 7.50 in (1066.8 x 457.2 x 190.5 mm)

CMDL 50 kA

CHMDL 65 kA

Digitrip 310

N-Frame 800/1200AMinimum enclosure size with ventilation42.00 x 22.75 x 11.50 in (1066.8 x 577.9 x 292.1 mm)

CND 50 kACHND 65 kACNDC 100 kA

Digitrip 310, Digitrip OPTIM

R-Frame 1600/2000AMinimum enclosure size with ventilation21.50 x 18.00 x 13.00 in (546.1 x 457.2 x 330.2 mm)

CRD 65 kACRDC 100 kA

Digitrip 310/510/610/810/910, Digitrip OPTIM

2000A F

2 A

A600A T

800A FA

00A FA

2000A Bus

Pnlb . A BusM A Bus

350 kcmil,Cu per phase

350 kcmil,Cu perphase

2–600 kcmil,Cu perphase

800A Busway

Feeder#1

Feeder#

Feeder#


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Application Information—Series Rated Systems020

Series Rated SystemsSeries rating is a short-circuitinterrupting rating assigned to acombination of two or more over-current devices connected in series.The short-circuit interrupting rating

of the upstream device must be equalto or greater than the available faultcurrent. Downstream breakers,however, are not fully rated for thesystem’s available fault current. Seriescombinations must be tested toUL 489. Series ratings are applied todistribution systems where short-circuit coordination is not required.The Eaton listing of available seriesrating combinations are shown in theapplications section of this document.

Under most circumstances, selectionof a series rated system will reduceinitial cost and size, because down-

stream breakers are not fully ratedfor the prospective short-circuit faultcurrent at their point of application.The interrupting rating of theupstream breaker must always beequal to or greater than the availablefault current at its line terminals. Inaddition, downstream breakers musthave been tested in combination withthe upstream breaker and shown to beprotected by the upstream breaker atthe assigned series rated interruptingrating. The net result is that the systemcan be assigned a “series rated” or“integrated” rating higher than therating of the downstream breaker when

it is tested or applied alone. Design ofthe system and selection of breakers isbased on short-circuit interruption testspecified and witnessed by UL.

Because of their blow-open design,most molded-case circuit breakers arecurrent limiting to some degree. In aseries rated application and in the eventof a major fault, both upstream anddownstream breakers open, protectingthe lower-rated downstream devicesby limiting the let-through current.

To develop a series rated protectivesystem, it is suggested that thedesign engineer, after completing

preliminary steps:■ Define available fault current at

the line side terminals of theupstream breaker

■ Select an upstream breaker with aninterrupting rating equal to or greaterthan the available fault current

■ Verify the series tested interruptingratings of the selected combinationof breakers by referring to the tablesin this section

■ Confirm, during installation, that thecorrect breakers have been selectedby checking the nameplates appearing on the end-use equipment

Evaluating the Protection Systems

Designed properly, series rated andfully rated systems protect electricalequipment with equal effectiveness.But initial cost and continuity of servicecan vary widely depending on theinherent characteristics of the system,and on the design philosophy adopted.

Fully Rated System

All breakers are rated for full faultcurrent at their point of application inaccordance with the National ElectricalCode. The continuity of service pro-vided by the system is greater than aseries rated system.

Series Rated System

A series rated system is less costlythan a fully rated system. Theupstream breaker is always fully rated,but the interrupting ratings of down-stream breakers are normally lower.Service continuity can be acceptableafter initial startup, because the lower-level arcing faults most likely occurafter that time can be cleared by thedownstream breaker alone. However,under high fault conditions, both theupstream and downstream breakerswould open, eliminating service tothe affected portion of the system.Therefore, it is not possible to achieveselective coordination for all magni-

tudes of available fault current witha series rated system.

National Electrical Code Requirements

Requirements of the National ElectricalCode for short-circuit ratings may nowbe met by equipment that is markedwith ratings adequate for the availablefault current at their point of applicationin the electrical system. Refer to thecurrent NEC for specific requirements.

General Discussion

Available Short-Circuit Current. Service equipment must be suitablefor the short-circuit current available

at its supply terminal.Approval. The conductors and equipment required or permitted by the Code willbe acceptable only if approved. SeeExamination of Equipment for Safetyand Examination, Identification,Installation and Use of Equipment.See definitions of “Approved,”“Identified,” “Labeled” and “Listed.”

Examination, Identification, Installationand Use of Equipment

1. Examination: in judging equip-ment, considerations such as thefollowing should be evaluated.

a. Suitability for installationand use in conformity withthe provisions of this Code.Suitability of equipment usemay be identified by a descrip-tion marked on or providedwith a product to identify thesuitability of the product for aspecific purpose, environmentor application. Suitability ofequipment may be evidencedby listing or labeling.

b. Mechanical strength anddurability, including, for partsdesigned to enclose and protectother equipment, the adequacy

of the protection thus provided.c. Wire-ending and

connection space.

d. Electrical insulation.

e. Heating effects under normalconditions of use and alsounder abnormal conditionslikely to arise in service.

f. Arcing effects.

g. Classification by type, size,voltage, current capacityand specific use.

h. Other factors that contribute tothe practical safeguarding of

persons using or likely to comein contact with the equipment.

2. Installation and use: listed orlabeled equipment must be usedor installed in accordance withany instructions included in thelisting or labeling.

Interrupting Rating

Equipment intended to break current atfault levels must have an interruptingrating sufficient for the system voltageand the current that is available at theterminals of the equipment. Equipmentintended to break current at other thanfault levels must have an interrupting

rating at system voltage sufficient forthe current that must be interrupted.


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Application Information—Series Rated System021

Circuit Impedance and OtherCharacteristics

The overcurrent protective devices,the total impedance, the componentshort-circuit withstanding ratings, andother characteristics of the circuit to

be protected should be so selectedand coordinated as to permit thecircuit protective devices used toclear a fault without the occurrenceof extensive damage to the electricalcomponents of the circuit. This faultwill be assumed to be either two ormore of the circuit conductors, orbetween any circuit conductor andthe grounding conductor or enclosingmetal raceway.

Motor Contribution

The fault current contribution ofmotors connected between seriesrated breakers must be considered.

Article 240.86(C) in the 2005 edition ofthe National Electrical Code states thatfor series ratings the sum of the motor,full-load currents cannot exceed 1%of the interrupting rating of the lower-rated circuit breaker. The actual faultcurrent contribution from inductionmotors is about four times their full-load current (impedance value of25%). For example, if the downstreambranch circuit breakers used in a seriesrated combination have an interruptingrating of 14,000A rms symmetrical for a480V system, the maximum full-loadcurrent of motors connected to thatpanel from the branch circuit breakers

is 140A (1%). For typical inductionmotors, this is equivalent to a totalhorsepower at 480V of approximately115 horsepower.

Design/Test Considerations for SeriesCoordinated Circuit Breakers

Test procedures for all Eaton molded-case circuit breakers intended forapplication in series connectedsystems are in full compliance withall applicable paragraphs of th

Documents

Mccb Eaton