desing and selectivity lv_ge
TRANSCRIPT
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Guide to Low VoltageSystem
Design and Selectivity
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UnaffectedOpens
imagination at work
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Contents
Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . .1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .2 National Electric Code
Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
.3 Selective System Design ConsiderationsGround Fault Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .4MCCB Layer Limitations - Riser / Feed Through Lug Panels . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . .5Automatic Transfer Switch (ATS) Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . .7Switchboard Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . . . . . . .7
Transformer / Current Limiting Reactor Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . . . .7
Design Tips Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .7 Selectivity for Existing Systems . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8 Arc Flash Considerations . . . . . . . .
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8Selective Low Voltage Circuit Breaker Pairings Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . .9 Popular GE Selective Circuit Breaker Pairings - Summary TableGE Circuit Breaker / Equipment Combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . .10 AppendixSelective Time Current Curve Templates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . . . . .1315 kVA with FB Primary & TEY Secondary Mains . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . . . . . . . . . . . . . .1430 kVA with FB Primary & TEY Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . . .16
30 kVA with FG Primary & FG Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .18
45 kVA with FG Primary & FG Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .20
75 kVA with FG Primary & FG Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .22
112.5 kVA with FG Primary & FG Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . . .24112.5 kVA with FG Primary & S7 Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . .26150 kVA with FG Primary & FG Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . .28
150 kVA with S7 Primary & S7 Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .30
225 kVA with FG Primary & S7 Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .32
300 kVA with S7 Primary & S7 Secondary Mains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . . . . . . .34
Typical GE Dry Type, 480 – 120/208V Transformer Impedances . . . . . . . . . . . . . . . . . . . . . . . . .
. . . . . . .36Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
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. . . . . . . . . . . . . . .37
Information provided herein may be subject to change without notice. Products in this publication are designed and manufactured in accordance
with applicable industry standards. Proper application and use o f these products is the responsibility of GE's customers or t heir agents inaccordance with the standards to which they were built . GE makes no warranty or guarantee, expressed or implied, beyond those offered in our
standard Terms and Conditions, in effect at the time of sale. Any questions about the information provided in this document s hould be referred to
GE.
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Foreword
GE's first application publication on instantaneous selectivity, GE Overcurrent InstantaneousSelectivity Tables (DET-537, available in the Publications Library at www.geelectrical.com) lists GE low voltage circuit breakers and the short circuit current to which they are selective.
Since that was published, product innovation, rigorous selectivity testing and real-world
experience with selectivity requirements have improved GE's selectivity solutions.
The 2008 National Electric Code® (NEC) included some refinement and additions to theoriginally published “Coordination” requirements for selectivity. While there is still nouniform interpretation of these requirements, many Authorities Having Jurisdiction (AHJs) inthe United States are enforcing instantaneous selectivity requirements for “Emergency” and“Required and Standby” systems. It can be expected that, once an AHJ has accepted these
requirements, they will accept later versions of the NEC articles, including NEC Article 708 – Critical Operations Power Systems.
Following the introduction of coordination requirements in Articles 700 and 701 in the 2005
edition of the NEC, “caution” was the operative word as users, designers and suppliers
adjusted their traditional design and procurement patterns to meet the new NEC selectivityrequirements. Because the regulations are interpreted differently by different AHJs, allinvolved responded to a variety of interpreted requirements. Today, GE will confidently
provide design assistance and selective solution quotations for the majority of customerapplications, regardless of the local AHJ interpretations.
This publication does not replace our original selectivity publication, but provides supplemental
information for those involved in the layout, design and quotation processes. The data inDET-537 continues to be the most comprehensive representation of selective circuit breaker
pairings that GE offers. In this publication, we convey the essentials of selective systemapplications in a more easily used context. When using DET-537, make sure you are using thelatest version available. The most current version can be found on GE's website.
http://www.geelectrical.com/http://www.geelectrical.com/http://www.geelectrical.com/http://www.geelectrical.com/
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IntroductionWhat is selectivity?
The electrical design industry has historically required electrical system circuit breakerselections and settings be validated with a short circuit and coordination study performed by alicensed engineer. These studies assure that circuit breakers are capable of interrupting the
available current and would operate “selectively.” Traditionally, “selectivity” in a low voltageelectrical system meant that the long time and short time portions of time-current curves (TCCs)
would be selective, i.e. the circuit breaker closest to the fault would trip first, maximizing theamount of the electrical distribution system left in service. In most cases, the circuit breaker
instantaneous overcurrent (IOC) TCCs would not be selective “on paper,” as they typicallyoverlap.
In Figure 1A, there is no “instantaneous selectivity” apparent on the TCC, as the instantaneous portion (below 0.1 seconds) of the curves show all three breaker characteristics overlapping.The long time and short time characteristics (above 0.1 seconds) do not overlap and are
therefore selective. In Figure 1B, the 1600 amp AKR and Spectra F200 circuit breakers areselective, as the instantaneous function of the AKR is not used, so there is no overlap of these
two characteristics.
Traditionally, selectivity between molded case circuit breakers (MCCBs) and insulated casecircuit breakers (ICCBs) was considered effective, even if there was an overlap of TCCs in theinstantaneous region. The most prevalent type of fault, the line to ground arcing fault, oftenlimits the fault current magnitude enough that the upstream circuit breaker IOC function does
not operate. If the fault is removed promptly, the likelihood of it escalating into a multi-phase, bolted type fault is very low. As a result, for a large majority of faults, the traditional long time,short time selectivity has been sufficient to produce selective operation of circuit breakers.
The 2005 and 2008 NEC extend the selectivity requirement to all possible fault types andmagnitudes for certain critical electrical circuits, i.e., those typically fed from automatictransfer switches (ATS). These circuits and requirements are those discussed in the following
NEC articles:Article 700: Emergency Systems (Legally Required), 700.28 Coordination
Article 701: Legally Required Standby Systems, 701.17 CoordinationArticle 708: Critical Operations Power Systems, 708.54 Coordination
CURRENT IN AMPERES CURRENT IN AMPERES
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10000.100.011001011Spectra F 200AA P TEY
TCCs are “selective” TCCs are not “selective” 1K 10K 100KSK 1000ATIME IN SECONDS1 10 100 1K 10K 100K10000.100.01100101Spectra F 200A20A 1P TEY
TCCs are “selective” 000/1600A AKRTIME IN SECONDS
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Curve 5.tcc Ref. Voltage: 480 Current Scale x10^0 Curve 5.tcc Ref. Voltage: 480 Current Scale x10^0
Figure 1A Figure 1B
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These requirements state that overcurrent protective devices (OCPD) must be “fully selective.”In other words, given the range of available interrupting currents, any given pair of overcurrent
devices covered by the NEC Articles referenced above must behave in a coordinated fashion asdefined in NEC Article 100:
“Coordination (Selective). Localization of an overcurrent condition to restrictoutages to the circuit or equipment affected, accomplished by the choice ofovercurrent protective devices and their r atings or settings.”
The NEC requirements are desirable design goals, given the adverse consequences of largerthan necessary power outages within critical circuits. However, there are other design
considerations that these requirements seem to preclude, i.e., arc flash and the specifics of phase and ground fault overcurrent coordination. The ability of fully selective designs to provide sufficient protection to such important, sensitive equipment as generators or automatic
transfer switches may be affected.
This publication uses the information on instantaneously selective breaker pairings contained
in DET-537 as a base, and goes on to discuss specific tactics for developing fully selectiveelectrical distribution designs. Though instantaneous selectivity is possible in many cases, it is
not always easily accomplished with the considerations mentioned above. It has long been theresponsibility of the licensed engineer of record to assess all performance requirements and
produce a balanced, practical design.
National Electric Code (NEC) Requirements
The 2008 NEC Articles 700.27, 701.18 and 708.54 requirements for Coordination say:
“... overcurrent devices shall be selectively coordinated with all supply side overcurrent protective devices.”
This wording does not exempt ground fault protection from selectivity, nor does it exempt
selectivity with the normal side supply sources. Even though this requirement is found in theSpecial Conditions chapter of the NEC dealing with Emergency Systems, Legally Required
Systems and Critical Operations Power Systems (COPS), it states the emergency overcurrent
protective devices must be selectively coordinated with all supply side overcurrent
protective devices. This terminology implies that selectivity with both normal and emergencysupply sources is required for both phase and ground fault OCPDs. (Note: The local AHJ has
the final word on interpretation of the NEC and other applicable code language. It isimportant to use their interpretation when designing and quoting selective systems.) Fullselective coordination in systems with ground fault protection can be difficult and is beyondthe intended scope of this publication.
To date, a large variety of interpretations of the NEC requirements have been made. Numerous
state and local AHJs have excluded these “Coordination” requirements from their enforcementcodes, or have modified them. At the time this publication was written, the most mentionedalternative to the NEC “full selectivity” requirements is the “0.1 second rule.” This definition
of selectivity has been adopted by some AHJs, including, most notably, Florida's Agency forHealth Care Administration (AHCA). This selectivity requirement preceded the 2005 NEC
requirements by decades.
The AHCA requirements are broader than those in the NEC as they apply to the entire facility,not just critical circuits. Therefore, faults on non-critical portions of the system will not result in
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an unwanted shutdown of critical circuits because of non-selective breaker operations. Thisstandard is often criticized because it only requires selectivity down to 0.1 seconds. However, it
represents the long-standing design practices employed be electrical systems designers. TheAHCA requirements, which allow the overlap of OCPD IOC functions, result in reducedclearing times and associated arc flash hazards and require selective coordination for the entirefacility.
The AHCA 0.1 second allowance does have sound engineering basis. It is probable that most
system faults are line to ground arcing faults on branch circuits. These faults will probably fall beneath the IOC threshold of the larger circuit breakers above the branch circuit breaker
nearest the fault. Ground faults in parts of a system with high short circuit currents may bequite high in magnitude. Sensitive ground fault protection is often sufficient to sense and cleararcing ground faults well below IOC levels of upstream devices. Two levels of selective
ground fault protection have been required in certain hospital systems by NEC Article 517 formany years.
It is important to note that “full selectivity” is often facilitated by increasing trip time delaysand increasing pickup thresholds in upper tier OCPDs. Allowing instantaneous protection to be
applied throughout the system improves protection and decreases arc flash hazard. The impactof designing for full selectivity in systems that require “live work” should be studied andunderstood so optimized design decisions can be made and hazards identified.
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The first words of NEC, Article 90.1, Purpose, are: “(A) Practical Safeguarding. The purpose
of this Code is the practical safeguarding of persons and property from hazards arising from
the use of electricity.” Historically, the NEC started by establishing protection requirements forlow voltage loads, cables, transformers, etc. This has always been and continues to be the
Code's first priority. While Articles requiring “fully selective” systems are consistent with the“Practical Safeguarding” requirements, these Articles do not take precedence over competing
protection and design needs.
In the absence of specific language in NEC Articles 700, 701 and 708 for coordination,interpretations of the NEC code vary significantly. Some interpretations require full selectivity
through the critical circuits, to both the normal and emergency supplies. Others require criticalcircuit breakers to be selective to the automatic transfer switch (ATS) using the normal supply
short circuit current, then continue the selectivity only to the emergency supply above the ATSusing the emergency source short circuit current. A third popular interpretation requires
selectivity through critical circuits to the emergency supply only. (Please note that the shortcircuit current from the emergency source is often much less in magnitude than the normalsupply.) Where this is the case, designers have more selective breaker pair choices and the
potential ability to reduce the size and cost of a selective system solution.
Some AHJ's and the State of Massachusetts require selectivity of critical circuits to beaddressed, but leaves the extent of the requirement to the discretion of the licensed professionalengineer of record. This allows the engineer to balance other design requirements, such as arcflash, with selectivity needs.
When designing a system for selectivity per NEC requirements, it is important to knowexactly how the AHJ has defined selectivity requirements and how they are verified and
enforced.
Selective System Design Considerations
Ground Fault Protection
Some selectivity requirement interpretations of the Code exclude ground fault
protection because it is not specifically addressed in Article 700, 701 or 708. Article 100
defines “Coordination” as:
“Localization of an overcurrent condition to restrict outages to the circuit orequipment affected, accomplished by the choice of overcurrent protective devicesand their ratings or settings.”
“Overcurrent” is defined as:
“Any current in excess of the rated current of equipment or the ampacity of aconductor. It may result from overload, short circuit, or ground fault.”
Even though ground fault selectivity is not expressly mentioned in Articles 700, 701, and 708,it is implied through the overriding NEC definitions of “selectivity” and “overcurrent.”
Traditionally, the shape of a ground fault protection characteristic applied on low voltagecircuit breakers would be called a “definite time” or “L-shaped” characteristic. (Note: Often,ground fault relays or ground fault protection integrated with circuit breaker trips will offer a
way to cut off the bottom left corner of the “L.” This cut -off corner is usually in the shape ofan I2t=K diagonal line on the TCC.)
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Typical GF protection characteristics are illustrated in the low voltage circuit breaker phase andground protection characteristics below. Their dissimilar shapes make selective coordination
difficult at best. The NEC (Article 230.95) requires thatground fault protection be applied on solidly grounded 480 volt service entrances, 1000amperes and larger.
Hospitals and other healthcare facilities with critical care or life support equipment arerequired to have a second level of ground fault protection beneath the service entrance (NEC
Article 517.17(B)). The NEC-stipulated maximum ground fault pick-up setting is 1200amperes and clearing time is limited by a requirement that a 3000A fault must be cleared in
one second or less (Article 230.95(A)). Emergency system supply sources are exempted fromthese requirements.
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Figure 2A is a one line diagram with two levels of ground fault protection as required by NECArticle 517. Figure 2B diagrams the selective device settings for this one-line diagram. Ground
fault relay settings for the 4000A main and 1200A branch feeder are selective and at themaximum allowed by the NEC. The next device below the 1200A branch is a 250A OCPD.
Note that there is significant overlap between the ground fault relays and the 250A deviceTCCs.
Traditional system designs would size the 250A OCPD to 600A or possibly 800A, making this
non-selective situation worse. In this and many similar situations involving phase and groundfault protection, this system would not be fully selective for ground faults, as an upstreamOCPD could trip sooner than the downstream OCPD.
MCCB Layer Limitations - Riser / Feed Through Lug PanelsSome traditional electrical system designs have utilized a “waterfall” of electrical distribution
panels of declining ampacities, i.e., a series of progressively smaller electrical distribution panels connected to larger upstream panels. This concept is popular because it allows the size
and cost of the distribution panels and feeder cables to be reduced further from the serviceentrance point. While this has been a satisfactory practice when long time and short timeselectivity is considered, the practice increases the difficulty of achieving “fully selective”solutions.
For “fully selective” designs, it is desirable to limit the number of selective circuit breakerlayers as there are a limited number of selective molded case circuit breaker (MCCB) pairingsavailable. If you consult GE's (or other manufacturers') circuit breaker instantaneous selectivitytables, you will usually find three or, in some circumstances, four layers of molded case circuit
breakers that can be made fully selective.
With a limited number of fully selective MCCB layers in mind, the best electrical distribution
design strategy is to limit the number of selective layers by utilizing feed-through lugs or riser panels of the same ampacity when sub-panels are required. When feeder cables and panels areall the same ampacity, only one layer of protection is required to protect them.
In doing so, the tradeoff is the elimination of a local main circuit breaker. Some designs willutilize a main disconnect at each panel to allow local isolation of a panel. Care must be
exercised if a molded case switch (MCS) is used as a main disconnect. The MCS will have anIOC override in the switch to protect it from damage resulting from high magnitude fault
currents. This instantaneous override must be considered as part of the selectively coordinatedsystem.
CURRENT IN AMPERES
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10000.100.0110010
Swbd feed14000A250 RK5
120020A TEY20A JMain GF Aer GFTIME IN SECONDS
4000AGF GF
1200AGF GF
20A250A
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10 100 1K 10K 100K
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1600A.tcc Ref. Voltage: 480 Current Scalex10^0
Figure 2A Figure 2B
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In Figure 3, the 400 ampere feeder is feeding three downstream panels. With the use of riser panels of the same ampacity, only two layers of selective breakers would be needed. If a
traditional design strategy of progressively smaller sub-panels had been used, four layers offully selective circuit breakers would be required for the waterfall of declining ampacities.
Fully Selective
Circuit Breaker
Options For
Systems with 65
kAI C or less
SOURCE
480V
LVPCB w/o instantaneous
LEG REQD ATS-1**
30-300 KVA
208V
FG
LIGHTING PANEL
FB*
65 kAIC maximum
MAIN SWBD
S7 - ICCB or MCCB req'd to protect 3cy ATS rating
MLO PANEL
FG or FB set to protect xfmr
FG600 600 AT Max
FG600
400 AT
PNL
PNL
PNL-2PNL-3
PNL
PNL-1
MLO w/ FTL or Riser panels, all equally rated w/ FB* branch breakers
* TEY or THQ MCCBs may be used, but only if the maximum AIC
specified in DET-537 is not exceeded. ** See selectivty templates
for details of transformer
Figure 3
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Automatic Transfer Switch (ATS) Protection
Most ATSs built for use in North America are manufactured in accordance with the UL 1008standard, which references UL 489 for molded case circuit breakers. Furthermore, many ATS
manufacturers provide application data specifying which MCCBs are appropriate for protecting the ATS ampacity and short circuit withstand ratings. In general, most ATSs aredesigned to be protected with circuit breakers that have integral IOC protection functions.
In some fully selective protection schemes, it may be necessary to protect an ATS with a lowvoltage power circuit breaker (LVPCB) applied without an IOC function. This may be anon-conforming application, which might require special consideration by the ATSmanufacturer. Some ATS manufacturers have published withstand data on such applications,
while others are considering future products with higher withstand time ratings in view of thenew selectivity requirements.
Switchboard Protection
Switchboards, distribution panels and lighting panels utilize MCCBs, ICCBs or LVPCBs withIOC functions. Therefore, the withstand ratings of these boards and panels are usually based on3 cycles. Similar to the ATS ratings discussed above, LVPCBs without an IOC function should
not be used to protect a switchboard unless special application consideration has been given toits withstand rating. Some manufacturers have 30 cycle withstand ratings for specificswitchboard designs. If selectivity requirements result in the use of LVPCBs without an IOCfunction or very high IOC settings, it is important to know the withstand ratings of thedownstream equipment.
GE has introduced UL Listed Spectra Series Switchboards rated for 30 cycles of short circuit
withstand. Since UL 891 does not have standard requirements for 30 cycle ratings, ANSI 37.20was used to validate the switchboard performance. These switchboard designs enable them towithstand longer duration faults.
Transformer / Current Limiting Reactor Applications
Considerations for NEC “fully selective” applications focus on the selective performance ofcircuit breaker pairs in the IOC regions of their TCCs. Usually, higher short circuit currentslimit the options for pairs of selective breakers. Consequently, some electrical designs useone-to-one ratio transformers or current limiting reactors to restrict fault current magnitudes.
This works well where one of these devices can provide a small amount of series reactance tocontrol the short circuit current to a magnitude where more options for selective breaker
pairings are available. It may not be effective if two-to-one or three-to-one reductions in shortcircuit current magnitude would be required to make selectivity possible.
Design Tips Summary
Note the actual calculated short circuit currents for the critical circuit buses on the bid drawings.Define the circuits and sources that must be made selective, according to the local AHJ
(preferable), the end customer or the engineer of record.
Limit service entrance short circuit current to less than 65 kA whenever possible.Limit the “critical” feeder sizes in the service entrance gear to 1200A maximum. Limit the number of MCCB selective layers below an ATS to two if using a 1200A frame
MCCB to protect the ATS.If ATS or switchboards are protected by an LVPCB without IOC, this equipment will
require a 30 cycle short circuit withstand rating.
Utilize main lug only (MLO) with FTL or riser panels to minimize required layers of fullyselective circuit breakers.
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Increasing the frame size of an ICCB or MCCB may increase maximum short circuit currentselectivity with a downstream breaker.
Small lighting transformer impedance can be used to limit the secondary short circuit current,with resulting full selectivity (secondary main IOC set above the secondary short circuitcurrent).
For systems with 35kA short circuit current or less:
– Utilize an LVPCB without IOC as the service entrance main as the fifth andtop layer of selective protection. – Utilize PB II as the fourth layer of selective
protection. – Utilize S7 MCCB as the third layer of selective protection. – Utilize FG MCCB as the second layer of selective protection. – Utilize FB, TEY, THQB MCCBs (depending on short circuit current requirement and
voltage at this level) as the bottom branch device layer of selective protection system.For systems with 65kA short circuit current or less,
– Utilize an LVPCB without IOC as the service entrance main as the fifth andtop layer of selective protection. – Utilize an LVPCB without IOC as the fourth
layer of selective protection. – Utilize S7 MCCB as the third layer of selective protection.
– Utilize FG MCCB as the second layer of selective protection. – Utilize FB, TEY, THQB MCCBs (depending on short circuit current requirement and
voltage at this level) as the bottom branch device layer of selective protection system.
Utilize lighting transformer TCC templates to define breaker applications for transformer protection and fully selective protection.Contact GE Specification Engineers in Florida for assistance with 0.1 second selectivity
requirements.
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Selectivity for Existing Systems
Several projects have been reviewed where NEC requirements for selectivity on criticalcircuits have been stipulated for add-on systems within pre-existing power distributionsystems. Interpretations of requirements for these situations have varied significantly.
Assuming that the critical circuits in the original system were designed to the “traditional”selective coordination requirements, adding new critical circuits under the existing system
would probably result in a non-selective system. Under fault conditions in the new portion ofthe circuit, the upstream, pre-existing breakers would probably be non-selective, resulting in a
potential shutdown of the entire new system for some faults. Where devices with instantaneous
trips from different manufacturers are mixed, it is unlikely that there is enough data todetermine the selectivity capability between them. The one application
exception to this would be the addition of a new sub-system under an ANSI circuit breakerthat was applied without an IOC function or a circuit breaker with an IOC threshold largerthan the AIC.
In some cases, a variance from the Code requirement has been requested and granted based onconsiderations of the difficulty in analyzing or achieving selectivity for systems involving a
mix of manufacturers. If absolute adherence to the new NEC requirements for add-on systemsis required, this will probably result in costly replacement of existing circuit breakers and
possibly equipment. Often, fully selective circuit breaker pairings and associated equipmentmay be larger and more expensive than breakers and equipment designed around traditionalselectivity definitions. Therefore, an expansion of the space allocated to original equipment
may be required.
Arc Flash Considerations
At the core of fully selective designs based on NEC Coordination (fully selective) requirements
is the concept of coordination of circuit breaker OCPD time-current characteristics. Practically,this means that the circuit breaker immediately upstream of the breaker closest to the fault will
be set (delayed or desensitized) to prevent it from operating until the downstream breaker clearsthe fault.
Considering that a typical 1500 kVA service entrance and associated power distributionsystem designed for full selectivity may have five layers of coordinated circuit breakers, the
time delayed response of the service entrance main breaker may be considerable. This timedelay could correspond to high arc flash incident energy and a correspondingly high HazardRisk category classification.
The Standard for Electrical Safety in the Workplace, NFPA70E, requires that all electricalhazards be identified by qualified personnel before work on electrical equipment is
undertaken. Usually, this requires assessment of arc flash hazard. Ideally, an Arc Flash Studyof the electrical system should be considered during design so that the consequences of design
decisions, including those made for selectivity purposes, are understood.
Increasing OCPD pickup settings, increasing IOC settings and adding time delays to obtainsfully selective design can have a significant impact on available incident energy. For systemslikely to be serviced while energized, these time delays may cause serious risk to personnel.
High incident energy levels may force the system to be shut down before any work can be
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performed. Additionally, excessive energy levels and time delayed (slow) protective deviceresponse may allow extensive fault related damage, requiring extensive down time and repair.
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THQ 35-60A
Selective Low Voltage Circuit Breakers Pairing Diagram-P2,3
4kATHQ 15-30-P2,36kATHQ 15-30A-P114kATEYF 15-30A-P1,2,314kAFE 250A-PTEY 15-30A2,3-PFE 250AFE 250A-P-P14.21,2,32,3
2,3 100kA10kA65kA
Maximum Short Drag Rating for CBs Listed Below
100kA 65kA 200kA 150kA 65kA 200kA 200kA 100kA 65kA 10kA 22kA208VFB 15-100
FB 15-100A1,2,3-P
-PFE 25-150A1,2,3
35.0kA
100kA 65kA150kA 100kA 65kA200kA 100kA 100kA 14kASF 250A
2,3-P-P2,3-P 2,3-P430V
2,310kA 10kA 22kA 22kA 2.5kA 2.5kA 2.5kA 14kA 14kA 65kA65kA 100kA65kA 65kAFrame Range500-3200A2000-800A4000-3000A 2000-800A1200-1000A 600-250A600-150A
100A 100A 125A 125AFE 250AFE 250A-P-P
All Other MCCB's 800A and Less2,3 71.3kA2,3 100kA
-PTEY 15-30A
1-PSE 150
2,3 12.8kA1-P 1,2,3-P 1,2,3-P 1-P
1,2,3-P 1,2,3-P 1-P 1,2,3-PFB 100A 1,2,3-PSE 150A1,2,3-P 1,2,3-P 1,2,3-P800A
Wave Pro Wave Pro PE111PE11157FG 599SE, SF, SGFBTEY THQ THHQPB2,WP, ENTELLIGUARD
(w/ INST.)TypeS7 1000/1200A-PTEYF 15-100A
SK w/MVT orMET 1200A
2,3-P1,2,3TEYF 15-100A10.8kA-PTHQ 15-100A3-P1,2,3
FB 100A 1,2,3-PTHQ 100A1,2,3-P 1,2,3-P 1,2,3-P-P27kA14kA21.6kA
1,2,322kA6kA 10kA 10kA 14kA 22kA65kA100kA15-100A1,2,3-P
SG w/MVT orMET 600A
2,3-PSF 250ATEY 70-100A-PFB 15-100A
All Other MCCB's 400A and Less
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TEY/THQ2,3 40.0kA
TEY 15-30A28.3kATHQ 100A10.8kA1-P 1,2,3-P-P
1,2,365kA22kAFG 250-400A-P-P-PTEY 35-60ASE 150TEY 15-100ASE 150-P
2,3 40kATEY 15-30ATEY 35-60A
2,3 71.2kA2,3 10.8kA
1600A2,3-P 1-P1,2,32,3-P 1-P 1,2,3-P1,2,3-P 1-P-P5.4kA
1,2,3PB2,WP, ENTELLIGUARD 3200-5000A14kA14kAPB2,WP, ENTELLIGUARD(w/ INST.)FG 250-600(WITHOUT INST.)-P-PTEY 35-60ATEYF 15-100ASF 250TEY 35-60ATEY 35-60A2,3
2,3 25kA67.4kA-P
1,2,3100kA14kA10kA 10kA57 1000/1200AFG 250-600A2,3-P 3-P
3-PTHQ 15-30ATEY 70-100ATEY 35-60A-P-P-P27kA2,3
1,2,32,365kAFG 600ATHQ 15-30ATEY 70-100ATEYF 15-100A
1-P 1-P
1-P44.0kA2000A-P-P
1,2,31,2,314kA4kAPB2,WP, ENTELLIGUARD
(w/ INST.)FG 400A-PTHQ 35-60ATEYF 15-100A2,32,3-P 1-P44.0kA-P
1,2,314kA100kAFG 250A-PTHQ 35-60A
2,3 44.0kA
THQ 70-100A
-P1,2,32.5kA
Figure 4
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Maximum AIC Ratings for Popular, Fully Selective Circuit Breaker Pairs
Instantaneous selectivity AIC values in these tables are for 277/480V and 120/208V ratings.THQB breakers listed are rated for 120/208V. SF, SE, FB, TEY and THQB breakers will
probably not be selective with any breakers applied downstream from them.
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TCC
Table 1A
Selectivity to be determined via TCC overlay method using
specific OCPD settings Selectivity probably not achievable
Main
Breaker
Bra
nch
Brea
ker
(ABB) S7H
** Record Plus
FG
Spec
tra
SF
Spect
ra
SE
Recor
d
Plus
FE
Recor
d
Plus
FB
Fra
me
TE
YF
No.
Poles3 3
3,2 3,2 3,2 3,23,2
3,23,2,1 3,2,1
Max
Sensor
or Trip*
12
001000
600 400 250 250
150
250
100 30
WavePro
(LSTrip)
5000 65.0
65.0
100.0
100.0 100.0 100.0
100.0
100.0
100.0 14.0
4000 65.0 65.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14.0
3200 65.0 65.0 100.0 100.0 100.0 100.0 100.0 100.0 100.0 14.0
2000 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 14.0
1600 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 65.0 14.0
800 NIS 65.0 65.0 65.0 65.0 65.0 65.0 14.0
WavePro(LSI
Trip)
5000 31.5
31.5
64.7
64.7 64.7 97.5
100.0
100.0
100.0 14.0
4000 32.4 32.4 69.0 69.0 69.0 100.0 100.0 100.0 100.0 14.0
3200 37.437.4
100.0100.0 100.0 100.0
100.0100.0
100.0 14.02000 27.0 27.0 44.0 44.0 44.0 67.4 71.2 100.0 100.0 14.0
1600 21.6 21.6 25.0 25.0 25.0 40.0 40.0 71.3 100.0 14.0
800 NIS 11.0 11.0 11.0 13.0 14.2 35.0 14.0
PowerBreak II
4000 32.432.4
69.069.0 69.0 100.0
100.0100.0
100.0 14.0
3000 35.1 35.1 85.0 85.0 85.0 100.0 100.0 100.0 100.0 14.0
2500 29.3 29.3 54.0 54.0 54.0 81.6 90.0 100.0 100.0 14.0
2000 27.0 27.0 44.0 44.0 44.0 67.4 73.0 100.0 100.0 14.0
1600 21.6 21.6 25.0 25.0 25.0 40.0 40.0 71.3 100.0 14.0
800 11.0 11.0 11.0 13.0 14.2 35.0 14.0
S7H (ABB) 1200 65.0 65.0 65.0 65.0 65.0 65.0 14.0
1000 65.0 65.0 65.0 65.0 65.0 65.0 14.0Record PlusFG
600 TCCTCC
TCC100.0
65.0 14.0
400 TCC TCC TCC TCC 65.0 14.0
250TCC TCC TCC 65.0 14.0
14.0
Record PlusFE
250
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* For Record Plus FG & FE and ABB
S7, maximum IOC is based on sensorsize
** S7 LTPU is 0.4-1.0 x sensor size
and does not use rating plugs
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Table 1B
Main
Breaker
Branc
h
Break
er
Frame TEY Q-Line THQB
No. Poles 3,2 1 3,2 1 3,2 1 2 3, 2 3, 2, 1 3 1
Max
Sensor orTrip
100
100
60 60
30 30
125 100
60 30
30
WavePro(LS
Trip)
5000 14.0
14.0
14.0 14.0 14.0
14.0
22.0 22.0
22.0 22.0
22.0
4000 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
3200 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
2000 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
1600 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
800 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
Wave
Pro
(LSITrip)
5000 14.0
14.0
14.0 14.0 14.0
14.0
22.0 22.0
22.0 22.0
22.0
4000 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
3200 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
2000 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
1600 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
800 12.8 12.8 12.8 12.8 12.8 12.8 18.1 18.1 18.1 18.1 18.1
Power BreakII
4000 14.014.0
14.0 14.0 14.014.0
22.0 22.022.0 22.0
22.0
3000 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
2500 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
2000 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
1600 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0800 12.8 12.8 12.8 12.8 12.8 12.8 18.1 18.1 18.1 18.1 18.1
S7H (ABB) 1200 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
1000 14.0 14.0 14.0 14.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
Record PlusFG
600 6.06.0
10.0 10.0 14.014.0
22.0 22.022.0 22.0
22.0
400 4.0 4.0 10.0 10.0 14.0 14.0 22.0 22.0 22.0 22.0 22.0
250 2.5 2.5 2.5 2.5 14.0 14.0 2.5 2.5 10.0 22.0 22.0
Record PlusFE
250 TCCTCC
TCC TCC 10.010.0
TCC TCC4.0 6.0
14.0
Table 1C
120/240V breaker ratingsFor 120/240V breaker pairs not listed below, use selective values from the
208 & 480V table above.
Main
Breaker
Bran
ch
Brea
ker
Record Plus FG
Spect
ra
SF
Spect
ra
SE
Recor
d
Plus
FB
No. Poles 3,2 3,2 3,2 3,2 3,2 3,2,1
Max 600 400 250 250 150 100
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Sensor
or Trip
WavePro(LSI
Trip)
5000 130
130
130
130
130
100
4000 130 130 130 130 130 100
3200 130 130 130 130 130 100
2000 130 65 65 130 130 65
1600 130 65 65 130 130 65
800 TCC 10 10 130 130 65
Power Break
II4000 100
100100
100100
100
3000 100 100 100 100 100 100
2500 92 92 92 100 100 100
2000 75 75 75 85 85 85
1600 42 42 42 72 72 85
800 TCC 10 10 14 17 32
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Table 2
GE Circuit Breaker / Equipment Combinations
Breakers Equipment
Enclos
ure
Mount
ed
A-Series II
PanelboardsA-Series
II
Powerpa
nel
Spectra
Powerpan
els
Switchboard
sSwitchgear
A
Q
A
E
A
D
AV-1,
2,5
AV
-3
PB
II
AKD
10
Entellis
ys
AKD
20
Mai
n
WavePro without
IOC
WavePro with
IOC
EntelliGuard
without IOC
EntelliGuard with
IOC
EntelliGuard G
without IOC
EntelliGuard Gwith IOC
Power Break II
ABB S7
Record Plus FG8/0
8
Record Plus FE200
9
200
9
Feed
er
WavePro without
IOC
WavePro with
IOC
EntelliGuardwithout IOC
EntelliGuard with
IOC
EntelliGuard G
without IOC
EntelliGuard G
with IOC
Power Break II
ABB S7 ABB
Record Plus FG
Record Plus FE 2009 8/08
Record Plus FB 3 8/08
TEY / TEYF 3
THQ 3
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Appendix
Selective Time– Current Curve TemplatesThe followed time-current curves were composed with the following objectives:
1. Achieve full selectivity (LT, ST and IOC) between each pair of circuit breakersapplied
2. Provide required NEC transformer protection3. Provide recommended ANSI through fault protection of transformers4. Provide the secondary power panel protection in accordance with its ampacity
(Note: To be “fully selective,” there must be no overlap of the long time and short timecharacteristics of an upstream and downstream circuit breaker pair. If the IOC function of this
pair of breakers overlap, then their instantaneous selectivity must be identified as selective in
the manufacturer's instantaneous overcurrent selectivity application literature.)
While it may be desirable to have the primary and secondary main circuit breakers selectivewith one another, it is not usual when applying MCCBs to protect transformers. In the 2008
NEC, a specific exception was added to exempt selectivity requirements from the primary and
secondary mains. The branch circuit breakers shown are the largest possible breakers and tripsthat will be fully selective with both the upstream primary and secondary main transformercircuit breakers. If selectivity between the branch breakers and the upstream secondary main isnot apparent because of IOC TCC overlap, the application is fully selective based on the
tabular pairing cited in DET-537, GE Overcurrent Device Instantaneous Selectivity Tables.
One other item of note is that the maximum AIC values shown in DET-537 are symmetrical
values. All analysis and testing done to validate these numbers were done with the appropriatestandard based X/R value and corresponding asymmetrical offset. The equivalent symmetricalvalue was placed in the tables. It has long been standard practice to terminate the IOC functionon a TCC at the maximum asymmetrical value of fault current, as IOC functions are oftenresponsive to the peak value of current.
The partial system templates diagrammed on the following TCCs were laid out and modeled based on a maximum fault current of 65 kA at 480V, with an X/R ratio of 4.9. Transformerimpedances used are the minimum for which a full selectivity solution could be achieved. Also
noted on the TCCs are the typical GE transformer impedances for aluminum wound, 150°Crated transformers. In every case, the impedance diagrammed is equal to or less than thetypical GE value. To make the solution as conservative as possible, no or negligible cableimpedances were included in the short circuit calculations.
While Article 450 of the NEC requires that transformers be properly protected fromovercurrent conditions, it allows several alternative approaches to achieve protection. For480V to 120/208V lighting transformers, 15 kVA and larger, the protection requirements are
described in Table 450.3B of the NEC. The two options described are to use a circuit breaker
as the primary main rated at no more than 250% of the primary ampere rating and a secondarymain circuit breaker rated at no more than 125% of the secondary. (Note: See NEC Table450.3 and associated notes for additional application allowances and restrictions.) It is also
permissible to use only a primary main circuit breaker rated at no more than 125% of the
primary ampacity.
In general, since the ANSI “through” fault protection criteria is a recommendation, it is
desirable to have the ANSI protection characteristic to the right of the primary and secondarycircuit breaker TCCs. However, it is the standard practice that adequate protection is still
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provided if most of the ANSI characteristic is to the right of the secondary main TCC.
In the TCCs that follow, A is always the transformer primary main and B is the secondary main
circuit breaker.
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A
B
C
480V
BUS-115 KVA
3.5%
65 KAIC (SYM)
A
B C*
208V
BUS-2
GE Record Plus MCCB Frame Type: FBN Frame Size: 100A Trip: 25A
GE TEY MCCB
Frame Type: TEY Frame Size: 100A Trip: 50A
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 20A
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Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 6.1%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
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15.6.81234678
9102346789100234678910002346789
10000.55555
Time-current CurveFully Selective Solution for 15 kVA TransformerCURRENT IN AMPERES X 10 AT 208 VOLTS8007001000 1000900 900600500400300200100908070605040302010 987654321.9.8.7.6.5.4.3
.2.1
.09
.08
.07
.06
.05
.04
.03
.02
.01 .01TIME IN SECONDS
K
V
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A
15
F
L
A
AGE
Re
cor
d
P
l
u
s
F
B
N
T
ri
p
Fr
a
m
e
=
=
10
0A25
A
15
KVA
3.5%
C
*
GETHQ
Q
Li
ne
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B
Fr
a
m
e
Tr
ip
=
20
A
=
10
0A
B GE
E1
50
T
E
Y
T
ri
p
Fr
a
m
e
=
5
0
A
=
1
0
0
A
1
5
K V
A
I
N
R
U
S
H
B12
17
A
8007001
0090
600
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50040030020080706050403020
10 98765432
1.9
.8
.7
.6
.5
.4
.3
.2.1
.09.08.07.06
.05.04
.03
.02TIME IN SECONDS
The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 3.5%65 kA (X/R=4.9) @ 480V; 1.2 kA @ 208V
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B
C
A
D
BUS-1
480V
65 KAIC (SYM)
A
30 KVA 4%
B 208V
BUS-2
C* D*GE Record Plus MCCB Frame Type: FBN Frame Size: 100A Trip Plug: 70A
GE Record Plus MCCB Frame Type: FGN Frame Size: 600A Sensor: 250A
Rating Plug: 100AIOC Setting: 11X (2750A)
* GE Q-Line MCCB
Frame Type: THQB Model C Frame Size: 100A-1,2P Trip: 50A
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 35A
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Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 5.6%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
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CURRENT IN AMPERES X 10 AT 208 VOLTS23456789
100234.5.6.81234567891056789
10002345678910000
Time-current CurveFully Selective Solution for 30 kVA Transformer.5.8123468
1023467910034678100023467910000.6
579585958800800700700
30 KVA FLA600
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600500500
BG
400400
E RecordPlus300300
200200
Trip =
100A
Inst = 11X (27
50A)1
0090
100908080707060605050
30 KVA4040
4%3030202010
910 98877665544332
21.9
1.9.8.8.7.7
Trip =
35A.6.6.5.5.4.4.3.3.2.2
C *30 KVA INRUSH
.1.09
.1
.09
.08
.08
.07
.07
Trip = 50A.06.06.05.05.04
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.04
.03
.03
.02
.02
B
2126ATIME IN SECONDS
1000 10900 900.01 .01
GE Q LineTHQB Model C - 1,2P Frame = 100A
D *
GE Q Line THQB
Frame = 100A
FGN
Frame = 250A
A
GE Record Plus FBN
Frame = 100A Trip = 70ACURRENT IN AMPERES X 10 AT 208 VOLTS
The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 4.0%65 kA (X/R=4.9) @ 480V; 2.1 kA @ 208V
TIME IN SECONDS
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BUS-1
BUS-2
B 208V
65 KA (SYM)
480V
A
30 KVA 4%
A
B
C
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D
GE Record Plus MCCB Frame Type: FGN Frame Size: 600A Sensor: 250ARating Plug: 100AIOC Setting: 11X (2750A)
GE Record Plus MCCB Frame Type: FGN Frame Size: 600A Sensor: 250ARating Plug: 100AIOC Setting: 11X (2750A)
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 50A
* GE Q-Line MCCB
Frame Type: THQB Model C Frame Size: 100A - 1, 2P Trip: 60A
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C* D*
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Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 5.6%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
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19.5.6.812345
6789102345678910023467891000
2345678910000
Time-current CurveFully Selective Solution for 30 kVA Transformer
TIME IN SECONDS1000 1000900 900400800700600500300
2001.1
.09
.08
.07
.06
.05
.04
.03
.02
.01 .010090
807060504030201
1.9
.8
.7
.6
.5
.4
.3
.209
8654327
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4%
30 KVA
GE Q Line THQB
Frame = 100A Trip = 50A
C*
THQB Modlel C - 1,2P
Frame = 100A
Trip = 60AD* GE Q
Line30 KVA FLA30 KVA INRUSHA
GE RecordP
Trip = 100A
Inst = 11X (2750A)FGN Frame =
2126A
B
250A
lus
Trip = 100A
Inst = 11X (2750A)B GE
FGN
Fra
RecordPlus
me = 250A8006005004003002001009080605040302010 9
8765432700701.9.8.7.6.5.4.3.2.1.09.08.07.06
.05
.04
.03
.02
CURRENT IN AMPERES X 10 AT 208 VOLTSTIME IN SECONDS
The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 4.0%
65 kA (X/R=4.9) @ 480V; 2.1 kA @ 208V
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45 kVA Transformer Template(with Record Plus Type FG Primary Main)
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480V
A
45 KVA
3.5%
B208VA
B
C
D
BUS-1
BUS-265 KA (SYM)C* D*
GE Record Plus MCCB Frame Type: FGNFrame Size: 600A
Sensor: 250ATrip: 100AIOC Setting: 11X (2750A)
GE Record Plus MCCB Frame Type: FGN
Frame Size: 600A
Sensor: 250ATrip: 150A
IOC Setting: 11X (2750A)
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 50A
* GE Q-Line MCCB
Frame Type: THQB Model C Frame Size: 100A - 1, 2P Trip: 60A
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Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 5.4%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
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CURRENT IN AMPERES X 10 AT 208 VOLTS34567891002
34.5.6.812345678910567891000234
5678910000.6.8123467891024678910023467891000234678910000.55555
Time-current CurveFully Selective Solution for 45 kVA TransformerCURRENT IN AMPERES X 10 AT 208 VOLTS800700800700
TIME IN SECONDS
1000 10900 9004002006005003001.01 .0140
00
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9080706050302014
09
8
76532
45
KVA
FLA
A
GE
F
G
N
Reco
rd
Pl
us
T
ri
p
I
n
st
F
=
1
1
X
10
0A
25
0A
(
2
7
5
0
A
)
B
GE
R
e
c
o
r
d
P
lu
s
FGNF
=
250A
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rame
T
ri
p
I
n
st
=
15
0A
=
11
X
(2750A
)
45
KV
A
3.5
%
C
*
G
EQ
Li
ne
T
H
Q
B
Fr
a
m
e
=1
0
0
A
T
ri
p
=
50
A
4
5
K
V
A
I
N
R
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U
S
H
D
*
G
E
T
H
Q
B
Q
Li
ne
M
od
el
C
F
ra
m
e =
10
0A
-
1,2P
T
ri
p
=
60
A
B
3627A
4002004020426005003001009080706050
3010 987653
TIME IN SECONDS1.9
.8
.7
.6
.5
.4
.3
.2
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.1.09
.08
.07
.06
.05
.04
.03
.021.9.8
.7
.6
.5
.4
.3
.2
.1
.09
.08
.07
.06
.05
.04
.03
.02
The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 3.5%65 kA (X/R=4.9) @ 480V; 3.6 kA @ 208V
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BUS-2
B 208V
65 KA (SYM)
BUS-1
480V
A
75 KVA
4.5%
C* D*
B
C
D
GE Record Plus MCCB Frame Type: FGN
Frame Size: 600A
Sensor: 250A
Trip: 110AIOC Setting: 11X (2750A)
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GE Record Plus MCCB Frame Type: FGN
Frame Size: 600A
Sensor: 400ATrip: 225A
IOC Setting: 11X (4400A)
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 100A
* GE Q-Line MCCB
Frame Type: THQB Model C Frame Size: 100A – 1, 2P Trip: 60A
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Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 6.0%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
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23
Time-current CurveFully Selective Solution for 75 kVA Transformer.5.6.812345678910234567891002345678910002345678910000800800700700
75 KVA600600
FLA500500400
4003003002002001
0090
10090808070706060
= 11X (2750A)
Inst50504040
75 KVA4.5%3030202010910 9887766
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554433
Trip
= 100A22
1.91.9.8.8.7.7.6.6.5.5.4.4.3.3.2.2
D*GE
75 KVAINRUSH
0A).1
.09.1.09.08.08.07.07.06.06.05.05.04.04.03.03.02.02
B
4704ATIME IN SECONDS
TIME IN SECONDS1000 10900 900.01 .01
Q Line
THQB Model C
Frame = 100A - 1,2P
Trip = 60A
C*
GE Q Line THQB
Frame = 100A
A
GE RecordPlus FGNFrame = 250A Trip = 110A
B
GE RecordPlus FGN Frame = 400A Trip = 225A Inst = 11X (440
CURRENT IN AMPERES X 10 AT 208 VOLTSThe following parameters are the basis of the above selective coordination plot:
Minimum allowable Z% = 4.5%
65 kA (X/R=4.9) @ 480V; 4.7 kA @ 208V
-
8/17/2019 Desing and Selectivity LV_GE
65/105
112.5 kVA Transformer Template(with Record Plus Type FG Secondary Main)
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66/105
65 KA (SYM)
BUS-1 480V
A
112.5 KVA
4.2%
A
GE Record Plus MCCB Frame Type: FGNFrame Size: 600A
Sensor: 400ATrip: 225A
IOC Setting: 11X (4400A)
B
GE Record Plus MCCB Frame Type: FGN
Frame Size: 600A
Sensor: 400ATrip: 350A
IOC Setting: 11X (4400A)
C
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 100A
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208V
BUS-3
B
C* D*
D * GE TEY MCCB
Frame Type: TEY, 3P Frame Size: 100A Trip: 60A
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Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 5.9%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
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25
CURRENT IN AMPERES X 10 AT 208 VOLTS2345678
9100234.5.6.8123456789105678
910002345678910000
Time-current CurveFully Selective Solution for 112.5 kVA Transformer.6.8123467810234679100234678100023467
910000.559585958800800700700
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112.5 KVAFLA
600600500500400400300300
A GERecordPlus200200
B GE
RecordPlus
Trip =
22
5A
11X (4400A)
Inst =1
0090
10090808070706060505040403030202010
910 9887766554
43322
D*GE
E1501.9
1.9
TEY Frame =.8.8
100A.7.7.6.6
Trip = 60A.5.5.4.4.3.3.2.2
C* GE Q
Line
THQB.1
.09.1.09
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112.5 KVA.08.08.07.07
INRUSH.06.06.05.05
.04
.04
.03
.03
.02
.02
B
7507ATIME IN SECONDS
1000 10900 900.01 .01
Trip = 350A
Inst = 11X (4400A)
FGN
Frame = 400A
112.5 KVA
4.2%
Frame = 100A
Trip = 100A
FGN
Frame = 400ACURRENT IN AMPERES X 10 AT 208 VOLTS
The following parameters are the basis of the above selective coordination plot:
Minimum allowable Z% = 4.2%65 kA (X/R=4.9) @ 480V; 7.5 kA @ 208V
TIME IN SECONDS
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A
B
C
D
112.5 kVA Transformer Template (with ABBS7 Secondary Main)
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BUS-2
208V
B
CA
112.5 KVA
4.2%
65 KVA (SYM)
BUS-1
480V
BUS-3
D* E*
GE Record Plus MCCB Frame Type: FGN
Frame Size: 600A
Sensor: 400ATrip: 225A
IOC Setting: 11X (4400A)
ABB S7 MCCB
Frame Type: ISOMAX Frame Size: 1200A
Sensor: 1000ALT Trip: 0.4X (400A)LT Delay: AST Trip: 10X (10000A)
ST Delay: DI2t: Out
IOC Setting: 12X (12000A)
GE Record Plus MCCB Frame Type: FGNFrame Size: 600A
Sensor: 250ATrip: 225A
IOC Setting: 11X (2750A)
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 100A
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E * GE TEY MCCB
Frame Type: TEY Frame Size: 100ATrip: 60A
Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 5.9%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
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Time-current CurveFully Selective Solution for 112.5 kVA Transformer
TIME IN SECONDS1000 10900 900400800
7006005003002001
.1.09.08.07.06.05.04.03.02.01 .01
0090
8070605040
302010
1.9
.8
.7
.6
.5
.4
.3
.286429753
Trip = 225AC GE
FGNFrame = 250A
Inst = 11X
RecordPlus
4.2%
112.5 KVA
(2750A)
E*
GE E150 TEY
Trip = 60A
Frame= 100A
THQB
Frame = 100A Trip = 100A
D*GE Q Line112.5 KVA FLA
112.5 KVA
INRUSH
A
GE RecordPlus
TripBABB
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Tap =
Sensor =Cur Set = 0.4X (400A)LT Band =
STPU = 10X (10000A)
ST Delay
STPU I2t = Out
FGN
Frame = 400A
Inst =
Inst =
= 2
PR212
1000A
11X
12X (12000A)
25A
C
7507A
S7 (1000ACT)
= D
A
(4400A)4004048007006005003002001009080706050302098765
321.9.8.7.6.5.4.3.2.1.09.08.07.06.05.04.03.0210
TIME IN SECONDS
The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 4.2%65 kA (X/R=4.9) @ 480V; 7.5 kA @ 208V
-
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77/105
150 kVA Transformer Template(with Record Plus Type FG Primary Main)
-
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78/105
480V
A
150 KVA
4.4%
AB
C
D
BUS-1
BUS-3
208V
65 KVA (SYM)
B
C* D*
GE Record Plus MCCB Frame Type: FBN
Frame Size: 600A
Sensor: 400ATrip: 250AIOC Setting: 11X (4400A)
GE Record Plus MCCB Frame Type: FGN Frame Size: 600A Sensor: 600ARating Plug: 450A
IOC Setting: 11X (6600A)
* GE Q-Line MCCB Frame Type: THQ Frame Size: 100A Trip: 100A
* GE Q-Line MCCB
Frame Type: THQB Model C Frame Size: 100A – 1, 2P Trip: 60A
-
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79/105
Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 4.4%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
-
8/17/2019 Desing and Selectivity LV_GE
80/105
TIME IN SECONDS
CURRENT IN AMPERES X 10 AT 208 VOLTS
.5
.81234567810234567910023456781000234567910000.69898
TIME IN SECONDS1000 10900 900400800700600500300200100
90.1
.09
.08
.07
.06
.05
.04
.03
.02
.01 .01408070605030201
1.9
.8
.7
.6
.5
.4
.3
.209
8765432
Trip = 450A
Inst = 11X (6600A)
B
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GE RecordPlFGNFrame =
4.4%
150 KVATHQB Frame
Trip = 100AC*
GETHQB Model C Frame = 100A - 1,2P Trip = 60A
D* GE Q
600A
Q LineusLine
= 100A150 KVA FLA
150 KVA
INRUSHA
GE RecordPlus
Trip = 250AFGN Fram
Inst = 11X (4400A)e =400A
9806A
B40020040204280070060050030010090807060503010 9876531.9.8.7.6.5.4.3.2.1.09.08.07.06
.05
.04
.03
.02
.5 .6 .8 1 2 3 4 5 67 8 9 10 2 3 4 5 67 8 9 100 2 3 4 5 67 8 9 1000 2 3 4 5 67 8 9 10
Time-current CurveFully Selective Solution for 150
kVA Transformer
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The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 4.4%
65 kA (X/R=4.9) @ 480V; 9.8 kA @ 208V
CURRENT IN AMPERES X 10 AT 208 VOLTS
-
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83/105
150 kVA Transformer Template (with ABB S7 Primary Main)
-
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84/105
-
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A
B
C
D
A150 KVA
4.4%
65 KA (SYM)
BUS-1
480V
BUS-2
B
C*
208V
BUS-3
D* E*ABB S7 MCCB
Frame Type: ISOMAX Frame Size: 1200A
Sensor: 1000ALT Trip: 0.4X (400A)LT Delay: AST Trip: 8X (80000A)
ST Delay: DI
2t: Out
IOC Setting: 12X (12000A)
ABB S7 MCCB
Frame Type: ISOMAX Frame Size: 1200A
Sensor: 1200ALT Trip: 0.4X (480A)
LT Delay: BST Trip: 8X (9600A)ST Delay: C
I2t: Out
IOC Setting: 12X (14400A)
GE Record Plus MCCB Frame Type: FGN
Frame Size: 600A
Sensor: 400A
Trip: 350AIOC Setting: 11X (4400A)
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 100A
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E * GE TEY MCCB
Frame Type: TEY FrameSize: 100A Trip: 60A
Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem
to indicate non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were
used to validate selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 4.4%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
-
8/17/2019 Desing and Selectivity LV_GE
87/105
31.6.812346 78
9102346 7891002346 78910002346 789
10000.55555
Time-current CurveFully Selective Solution for 150 kVA TransformerCURRENT IN AMPERES X 100 AT 208 VOLTS87800700
TIME IN SECONDS
18 ;8
6543
.09..
.
.
.
.01 .01
000000
150
K
V
A
00 FL
A00ABBPR212
00 ensorTap=1200A
=
S7
(
1
2
0
0
A
C
-
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T
)00 15
0
4.4
%
K
VA
Cur
Set
LT
Ban
d
STP
U =
=
0.
4
X
=
B
8
X
(9
60
0
A
)
(4
80
A)
00
ST
Dela
y
= C
90
80STP
U I2t
=
Ou
t
Inst
=
12X
(
1
4
4
0
0
A
)60
30
4020
8
6
5
4
3
21
A
A
B
BPR212
GEE150
GE
9Sensor= S7 (1
-
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0
0
0
A
C
T
)
8
7
Fram
e =
10
0A
T
a
p
=
1000A
6
Trip
= 60A
C
u
r
Set =
0.4X
(4
0
0
A
)5 L
T
Band
= A4
ST
PUST
=
3 C
*
GE
Re
cor
dPl
us
STP t=
U I
2 FG
N
Fra
meTri
p =
=
40
0A
35
0A
1
50
K
VA
I
n
st
= 12X
(12000
A)
1 Inst =
11
X
(
4
4
0
0
A
)
I
N
R
U
SH
*
GE
Li
ne
-
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T
H
Q
B
Fr
am
e=
10
0
A
Trip =
10
0A
B A
9806A 82
17
9A
60040020010090
60
40206425003008070503010987531.9.8.7.6.5
.4
.3
.2TIME IN SECONDS
21
.
.
.1
.09
.08
.07
.06
.05
.04
.03
.02
The following parameters are the basis of the above selective coordination plot:
Minimum allowable Z% = 4.4%65 kA (X/R=4.9) @ 480V; 9.8 kA @ 208V
-
8/17/2019 Desing and Selectivity LV_GE
91/105
225 kVA Transformer Template (with ABB S7 Secondary Main)
-
8/17/2019 Desing and Selectivity LV_GE
92/105
A
B
C
D
480VA
208V
B
BUS-1
BUS-2
65KA (SYM)225 KVA
4.1%
C
1BUS-3
D*GE Record Plus MCCB Frame Type: FGN Frame Size: 600A Sensor: 600ARating Plug: 450A
IOC Setting: 11X (6600A)
ABB ISOMAX MCCB Frame Type: S7
Frame Size: 1200A
Sensor: 1000ALT Setting: 0.7X (700A)
LT Delay: B
ST Setting: 10X (10000A)ST Delay: D
I2t: OutIOC Setting: 12X (12000A)
1 GE Record Plus MCCB Frame Type: FGN Frame Size: 600A Sensor: 600ARating Plug: 400A
IOC Setting: 11X (6600A)
* GE Q-Line MCCB Frame Type: THQB Frame Size: 100A Trip: 100A
-
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93/105
Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate
selective operation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole
configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 7.0%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values
1 FG400 and FG600 are selective with all THQB MCCBs. Certain THQBs not selective with FG250
MCCBs.
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TIME IN SECONDS
CURRENT IN AMPERES X 10 AT 208 VOLTS
.5
.81234567810234567910023456781000234567910000.69898
TIME IN SECONDS
1000 10900 9004002008007006005003001
.1.09
.08
.07
.06
.05
.04
.03
.02
.01 .0140
0090
8070605030201.9.8.7.6.5
.4.3
.24
09
8765321
Tap = 1000A Cur Set = 0.7XB ABB
Sensor = S7
-
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LT Band = B STPU = 10X
(10000A)
ST Delay = D
STPU I2t = Out
Inst = 12
PR212
X (12000A)
(1000ACT)4.1%
225
(700A)
Trip = 400A
Inst = 11X (6600A)C GE
FG
Fram
KVA
N
RecordPlus
D*
GE Q Line
THHQB
Frame = 100ATrip = 100A
e = 600A225 KVA FLA
225 K
INRU
VA
SH
Trip
A
GE RecordPlus
FGN
Frame = 600A
Inst = 11X (6600A)
= 450A
B16319A800600400200806050402010 9865432700500300100
90703071.9.8.7.6.5.4.3.2.1.09.08.07
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.06
.05
.04
.03
.02.5 .6 .8 1 2 3 4 5 67 8 9 10 2 3 4 5 67 8 9 100 2 3 4 5 67 8 9 1000 2 3 4 5 67 8 9 10
Time-current CurveFully Selective Solution for 225
kVA Transformer
The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 4.1%65 kA (X/R=4.9) @ 480V; 16.3 kA @ 208V
CURRENT IN AMPERES X 10 AT 208 VOLTS
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A
B
300 kVA Transformer Template (with ABB S7 Secondary Main)
-
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98/105
65KAIC (SYM)
BUS-1
480V
A
300 KVA
4.0%
BUS-2
B
C
208V1
BUS-3
D*, 2 E*C
D
E
ABB ISOMAX MCCB Frame Type: S7
Frame Size: 1200A
Sensor: 1000ALT Setting: 0.5X (500A)
LT Delay: BST Setting: 10X (10000A)
ST Delay: DI2t: Out
IOC Setting: 12X (12000A)
ABB ISOMAX MCCB Frame Type: S7
Frame Size: 1200A
Sensor: 1000ALT Setting: 1.0X (1000A)
LT Delay: AST Setting: 10X (1000A)
ST Delay: DI2t: Out
IOC Setting: 12X (12000A)
1 GE Record Plus MCCB Frame Type: FGN Frame Size: 600A Sensor: 600ARating Plug: 500AIOC Setting: 11X (6600A)
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*2 GE Q-Line MCCB Frame Type: THHQB Frame Size: 100ATrip: 100A
* GE Record Plus MCCBFrame Type: FBNFrame Size: 100A
Trip: 100
A
Notes:
Where an overlap of the time-current curve, instantaneous overcurrent characteristics seem to indicate
non-selectivity, GE Overcurrent Instantaneous Selectivity Tables, DET-537, were used to validate selectiveoperation.
Unless otherwise noted, overcurrent protective devices shown are for all available pole configurations.
GE typical transformer impedance: 150°C rise, aluminum winding, Z = 7.4%
This Z% is equal to or greater than the minimum allowed on this coordination plot
* Base layer circuit breaker settings are “not to exceed” values 1 FG400 and FG600 are selective with all THQB MCCBs. Certain THHQBs not selective with FG250 MCCBs.2 THHQB can only be used if AIC is less than 22 kA at the THHQB MCCB
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3510
CURRENT IN AMPERES X 10 AT 208 VOLTS234567
89100234.5.6.81234567895678
910002345678910000.5.6.812345678
9102345678910023456789100023
45678910000
Time-current CurveFully Selective Solution for 300 kVA TransformerCURRENT IN AMPERES X 10 AT 208 VOLTS
TIME IN SECONDS1000 1900 9
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4002008007006005003001
.1.09.08.07.06.05.04.03.02.01 .014020
0090
80706050301
1.9
.8
.7
.6
.5
.4
.3
.242
09
87653
GE Q Line
THHQB
Frame = 1
Trip = 100A
D*
FGN
Frame = 600A
Trip = 500A
Inst = 11X (6600A)
FBNFrame = 100A
Trip = 100A
CGE RecordPlusE*
GE Record Plus
00A
4%
300 KVA
300 KVA
FLAA
AB
Sensor = S7 (1000ACT)
Tap = 1000A
Cur Set = 0.5X (500A)
LT Band = B
STPU = 10X (10000A)
ST Delay = D
STPU I
2
t = Out
Inst = 12 X (12000A)
300 KVA
INRUSH
B PR212
B
ABB PR212
Sensor = S7 (1000ACT)
Tap = 1000A
Cur Set = 1X (1000A)
LT Band =
STPU = 10 X (10000A)
ST Delay = D
STPU I2t =
Inst = 12X (12000A)
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C
22434A
Asymmetrical
A
Out40020040204
280070060050030010090
807060503010 9876531.9.8.7
.6
.5
.4
.3
.2
.1
.09
.08
.07
.06
.05
.04
.03
.02TIME IN SECONDS
The following parameters are the basis of the above selective coordination plot:Minimum allowable Z% = 4.0%65 kA (X/R=4.9) @ 480V; 22.4 kA @ 208V
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Typical GE Dry Type Transformer Data
Table 3
480V Delta to 208/120V Wye, TP-1 Transformers
kVA °C Rise Aluminum Copper
Cat. No.%
R
%
X
%
Z
X/
RCat. No. %R
%X %Z X/
R
15 150 9T83B3871 5.1 3.3 6.1 0.6 9T83C9871 4.3 2.2 4.8 0.5
115 9T83B3871G15 5.13.3
6.10.6 9T83C9871G1
54.3
2.24.8 0.5
80 9T83B3871G80 5.13.3
6.10.6 9T83C9871G8
01.3
2.12.5 1.6
30 150 9T83B3872 3.7 4.2 5.6 1.1 9T83C9872 2.8 4.3 5.1 1.8
115 9T83B3872G15 3.74.2
5.61.1 9T83C9872G1
52.8
4.35.1 1.8
80 9T83B3872G80 2.12.7
3.41.3 9T83C9872G8
01.9
2.33 1.2
45 150 9T83B3873 3.5 4.1 5.4 1.2 9T83C9873 3 3.5 4.6 1.2
115 9T83B3873G15 3.54.1
5.41.2 9T83C9873G1
53 3.5 4.6 1.2
80 9T83B3873G80 1.33.1
3.42.4 9T83C9873G8
0 1 2.5 2.7 2.5
75 150 9T83B3874 3.9 4.5 6.0 1.2 9T83C9874 3.4 4 5.2 1.2
115 9T83B3874G15 2.84.7
5.51.7 9T83C9874G1
52.7
3.54.4 1.3
80 9T83B3874G80 1.13.5
3.73.2 9T83C9874G8
01 2.6 2.8 2.6
112.5 150 9T83B3875 3.1 5.0 5.9 1.6 9T83C9875 2.7 3.8 4.6 1.4
115 9T83B3875G15 2.34.1
4.71.0 9T83C9875G1
52.5
4.85.4 1.9
80 9T40G0005G81 1.82.2
2.81.2 9T45G0005G8
11.5
1.92.4 1.3
150 150 9T40G0006 2.4 3.7 4.4 1.5 9T45G0006 2 3.1 3.7 1.6
115 9T40G0006G51 2.43.7
4.41.5 9T45G0006G5
12 3.1 3.7 1.6
80 9T40G0006G81 2.43.7
4.41.5 9T45G0006G8
12 3.1 3.7 1.6
225 150 9T40G0007 4.3 5.6 7.0 1.3 9T45G0007 3.7 4.6 5.9 1.2
115 9T40G0007G51 2.45.0
5.51.9 9T45G0007G5
12 3.8 4.3 1.9
80 9T40G0007G81 2.64.9
5.61.9 9T45G0007G8
12 3.8 4.3 1.9
300 150 9T40G0008 4.0 6.2 7.4 1.6 9T45G0008 3.3 4.6 5.7 1.4
115 9T40G0008G51 1.85.2
5.52.9 9T45G0008G5
11.6
3.23.5 2.0
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Glossary
AbbreviationsAHJ Authority having jurisdictionAIC Amperes interrupting currentATS Automatic transfer switch
FTL Feed through lugsICCB Insulated case circuit breaker (UL Standard 489 rated)
IOC Instantaneous overcurrentkA Kilo-amperes
LVPCBLow Voltage Power Circuit Breaker (ANSI Standard C37. rated)MCCBMolded Case Circuit Breaker (UL Standard 489 rated)
MCS Molded Case Switch
NEC National Electric Code
OCPD Overcurrent Protective Device
V Volts
xfmr Transformer
Terms As Used in This Publication0.1 second selectivity
Two adjacent OCPDs are selective with one another over the full range of AIC, but only downto 0.1 seconds on the TCC. This suggests that their long time and short time characteristics areselective with one another, but that their instantaneous characteristics (that portion of the TCC
below 0.1 seconds) may not be selective
Code
National Electrical Code
Downstream / Upstream
A circuit breaker's or OCPDs location relative to the power source. For example, a main circuit
breaker in a panel is closer to the power source than a (smaller sized) branch breaker in thesame panel is upstream of the branch breaker. Correspondingly, the branch breaker isdownstream of the main breaker in this example.
Full Selectivity
In the context of NEC Articles 700, 701 and 708, this means two adjacent OCPDs are selective
with one another over the full range of available fault current magnitudes and for all types offault current.
Layer
On a one-line diagram, circuit breaker or OCPD layers are counted from a load back to a power
source. Each circuit breaker placed above another on the circuit back to the source is anotherlayer.
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GE
41
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