Arc Flash Analysis Oct 12 2010.pdf

Schneider Electric Engineering Services, LLC

2365 Harrodsburg Road, Suite B325 Lexington, KY 40504

(859) 296-3600

COVER LETTER

COVER PAGE

SHORT-CIRCUIT,

OVERCURRENT DEVICE COORDINATION &

ARC FLASH HAZARD ANALYSES

USDA National Animal Disease Center Ames, IA

Prepared by C.J. Joshlin, P.E.

Chris Fraley

Schneider Electric Engineering Services, LLC Job Number - August 27, 2010 Q2C: 27869250 Rev. 1 October 12, 2010

Project: 10357 Rev. 2 - Rev. 3 -

ELECTRICAL CONTRACTOR Baker Electric

DISTRIBUTOR Electrical Engineering & Equipment

SQUARE D FIELD ENGINEER Steve Wolter / Des Moines

FILE: ML10357 Rev 1

Revised October 2010

The following power systems engineering report was prepared by Schneider Electric Engineering Services, LLC utilizing industry-accepted standards, practices, methodologies, and analysis tools. Data used in this analysis was acquired by Schneider Electric Engineering Services, LLC and provided by others, through onsite discovery, published information, equipment nameplates, manufacturer ratings, testing, analysis, or other means. Schneider Electric Engineering Services, LLC assumes no responsibility for inaccuracies in data provided by others. The study is intended for use by qualified individuals to facilitate the installation, operation, maintenance, and safety of the electrical power system depicted. Modification of equipment, changes to system configuration, adjustment of protective device settings, or failure to properly maintain equipment may invalidate these results.

TABLE OF CONTENTS

1 EXECUTIVE SUMMARY

1.1 Introduction

1.2 Scope of Work

1.3 Results and Recommendations

2 SHORT-CIRCUIT ANALYSIS

2.1 General Procedure

2.2 Data Used in the Calculations

2.2.1 Power Company Data

2.2.2 Cable Data

2.2.3 Transformer Data

2.2.4 Motor Contribution To Short-Circuit Current

2.2.5 Assumptions

2.3 Short-Circuit Analysis Results and Recommendations

2.4 Short-Circuit Evaluation Table

3 OVERCURRENT DEVICE COORDINATION ANALYSIS

3.1 General Procedure

3.2 Specific Procedure

3.2.1 Short-Circuit Current Considerations

3.2.2 Molded Case Breaker Coordination

3.2.3 Low-Voltage Ground Fault Relay Settings

3.2.4 Transformer Protective Devices

3.2.5 Cable Protection

3.2.6 Selective Coordination and the 2008 NEC

3.3 Analysis of Results and Recommendations

3.3.1 TCC Plot Remarks

3.4 Overcurrent Device Setting Table

3.5 Time-Current Coordination Graphs - Recommended Settings

4 ARC FLASH HAZARD ANALYSIS

4.1 General Procedure

4.2 Specific Procedure

4.3 AF Hazard Analysis Results and Recommendations

4.3.1 Arc Flash Hazard Table Headings Guide and PPE Table

4.3.2 Arc Flash Hazard Analysis Table – Recommended Settings

4.4 Schneider Electric Engineering Services, LLC Arc Flash Labeling Practice

4.4.1 Arc Flash Information Labels

4.4.2 General Safety Labels

APPENDIX A: ABBREVIATIONS AND TRADEMARKS

APPENDIX B: SHORT CIRCUIT INPUT TABULATIONS

APPENDIX C: SHORT CIRCUIT OUTPUT TABULATIONS

APPENDIX D: REFERENCES

APPENDIX E: SYSTEM STUDY ONE-LINE DIAGRAMS

1 EXECUTIVE SUMMARY

1.1 Introduction

This report documents the results of a Schneider Electric Engineering Services, LLC analysis for the USDA National Animal Disease Center in Ames, IA. All studies were performed using the Power*Tools for Windows Software, version 6.5.1.4.

Data was obtained from the sources listed in the "REFERENCES" section at the end of the report.

Abbreviations and trademarks referenced throughout this report are also listed in an appendix.

The system short-circuit analysis evaluates the adequacy of the distribution equipment shown on the enclosed one-line diagrams to withstand or to interrupt the calculated maximum available short-circuit current at its location.

The overcurrent device time-current coordination analysis determines the suggested settings and, where appropriate, the ampere ratings and types for the electrical power system protective devices to achieve the desired system protection and electrical service continuity goals.

The flash hazard analysis establishes the flash protection boundary around electrical equipment within which a worker exposed to an arcing fault would expect to receive 2nd degree burns if not adequately protected. The analysis also determines the incident energy levels at specific working distances from equipment, which can be used to select appropriate personal protective equipment (PPE) to be worn when working within the flash protection boundary.

This report supersedes and invalidates results from any study, performed by Schneider Electric Engineering Services, LLC or any other entity, for the scope of equipment being reviewed.

Electrical system changes within the facility or in the utility system can have a significant impact on the results of this power system analysis, which is a “snapshot” of system conditions. As such, it is recommended that this analysis be re-evaluated on a regular basis, not to exceed 5 years, to account for electrical system changes. Failure to properly maintain equipment may invalidate these results.

1.2 Scope of Work

The scope of this study is limited to that equipment shown on the study one-line diagrams located in the back of the report. Unless specifically required by job specifications, branch circuit utilization equipment, as defined per NEC Article 100, was not included in this study (this may consist of small equipment, 100A and less, such as: safety switches, industrial control panels, and enclosed starters/drives).

1.3 Results and Recommendations

Short-circuit:

The results of the short-circuit analysis show that the equipment considered in the study is adequately rated for the projected fault current levels. However, some equipment could not be evaluated because the equipment’s rating could not be determined at the time of study preparation.

NEC 110.9 requires equipment to have a rating sufficient for interrupting the maximum available fault current present at the line side terminals of the equipment. NFPA 70E Article 210 also requires electrical equipment to have appropriate ratings to withstand or interrupt the available fault current. Where calculated available fault currents exceed the ratings of the equipment, remedial action, possibly including upgrade or replacement of the affected equipment, is required to comply with the NEC, NFPA 70E, and OSHA regulations. A risk of equipment damage, property damage, and personal injury exists when equipment has either inadequate withstand ratings or contains overcurrent protective devices (OCPDs) with inadequate interrupting ratings.

Equipment with inadequate ratings in this category can suffer damage which may include bent busbars, melted contactors, ruptured enclosures, or OCPDs may not be able to interrupt faults (three-phase bolted or arcing) properly.

For further discussion regarding these results, please refer to the Short Circuit Analysis Results and Recommendations section.

Coordination:

Circuit breaker settings provided offer the best compromise between protection and coordination based on the flexibility of the settings of each particular circuit breaker. The time-current coordination plots provided should be reviewed to determine if the degree of coordination shown is acceptable. If selective coordination according to NEC 700 is required, further analysis beyond the scope of this study will be necessary. In general, additional levels of distribution make it difficult to achieve selective coordination according to NEC 700 without oversized electrical equipment (ampacity and physical footprint). Larger equipment and changes to the cable and conduit layout may have an impact on the architectural design.

The breakers in the system should be set to the recommended levels. For further discussion regarding these results, please refer to the Time Current Coordination Analysis of Results and Recommendations.

Arc Flash:

The results of the arc flash analysis show both the calculated arc flash incident energy (AFIE) and flash protection boundary distances at each bus under study.

There were six arc flash fault current cases considered. Details of each case are noted on the Arc Flash Hazard Analysis Table. The results of all the cases were combined into one composite table showing the worst case results for each piece of equipment evaluated.

It is recognized that recommendations in this report may not be implemented simultaneously. It is Customer’s / Owner’s responsibility to apply and update labels as recommendations are implemented or as conditions change.

Note that the arc flash hazard analysis and recommended PPE levels are no substitutes for safe work practices. As stated in NFPA 70E, burn injuries can occur even when adequate PPE is employed, and the recommended PPE may provide little or no protection against arc blast and its effects. Protection from arc flash can best be provided by working only on circuits or equipment that have been placed in an electrically safe work condition. Work should not be performed on or near equipment listed “Dangerous” unless it has been placed in an electrically safe work condition.

Refer to each subsequent “Analysis of Results and Recommendations” section for further details.

If these issues are addressed by equipment, conductor, or device settings changes, the power system study results may need to be re-evaluated in a revision to this study.

2 SHORT-CIRCUIT ANALYSIS

2.1 General Procedure

An electrical system short-circuit analysis is used for the following:

1) To compare the calculated maximum fault current with the interrupting ratings of overcurrent protective devices such as fuses and circuit breakers.

2) To investigate applicable short-circuit series ratings and the protection of electrical equipment by current-limiting devices.

3) To verify the adequacy of other equipment, such as switches and equipment bussing, to withstand the effects of the calculated maximum fault current levels.

4) To assist in the selection and/or determination of settings for relays, fuses and circuit breakers.

5) To provide input (along with device trip characteristics) to an arc flash hazard analysis.

This analysis was made utilizing SKM Power Tools software. The software was programmed to calculate the maximum available three-phase, RMS symmetrical, short-circuit amperes at each piece of equipment in the system. The calculation procedures are based on recommendations included in ANSI/IEEE standards C37.13, C37.010, and C37.5.

The AFAULT module of the Power*Tools software simulates a bolted three-phase fault at each point of consideration in the system and calculates the maximum available short-circuit current at that point without any reduction due to current-limiting overcurrent devices which may be present.

(However, the effects of current-limiting devices are considered when determining the adequacy of the equipment.) The calculated short-circuit values are RMS symmetrical amperes and are comparable with the RMS symmetrical short-circuit ratings of electrical equipment.

Electrical distribution equipment must be able to withstand and/or interrupt the most severe fault duty that it may be subjected to at its location in the system. In particular, NEC Section 110.9 requires circuit breakers to have a rating sufficient for interrupting the maximum available fault current present at their line side terminals. For locations where calculated fault currents exceed the ratings of the equipment, recommendations for corrective actions are provided.

Equipment short-circuit withstand and interrupting ratings are expressed in symmetrical RMS current. However, fault currents are not purely symmetrical in practice, as system inductance introduces a degree of asymmetry for at least the first few cycles of a fault. The magnitude and duration of this asymmetrical component depends on several factors, including characteristics of system components (conductors, transformers, and loads) and the exact point on the current waveform that the fault begins—the level of asymmetry even differs from phase to phase in a three-phase system. Because of the uncertainty in asymmetry for a given fault event, the capability of devices to interrupt asymmetrical fault current is based on the maximum possible asymmetrical fault current level at the point of application. The more inductive the circuit, as measured by the calculated system X/R ratio, the more asymmetrical the fault current can be. If the calculated X/R level exceeds a certain level, then the increased asymmetrical duty must be taken into account when breaker ratings are assessed.

Low-voltage circuit breakers and fuses are tested to establish their interrupting ratings based on a circuit with a fixed X/R ratio, as defined in the various product standards (UL and ANSI). For example, an ANSI low-voltage power circuit breaker is tested in a circuit with an X/R ratio of

6.591. If such a breaker is applied at a system bus with a calculated X/R ratio of 6.591 or less and the calculated RMS symmetrical fault current is within the symmetrical interrupting rating of the breaker, then it is assumed that the breaker is also able to interrupt and withstand the asymmetrical current resulting from a fault at that location. If a low voltage breaker is applied at a location with an X/R ratio greater than that of the design test circuit, the calculated fault current must be multiplied by an adjustment factor that accounts for this. This resultant “fault duty,” which is greater than the calculated fault current, is then compared to the breaker’s interrupting rating in order to determine if the breaker is adequately rated. Different classes of low-voltage breakers have different test X/R values, and each type has its own set of multiplication factors. Design test circuit power factors and associated X/R ratios are as shown in Table 1. The SKM low-voltage short-circuit output report shows the calculated fault duty levels calculated at each bus, and when these values differ from the calculated short-circuit current levels, they are used in the device evaluation tables. See IEEE 1015-1997, IEEE Recommended Practice for Applying Low-Voltage Circuit Breakers Used in Industrial and Commercial Power Systems, for additional details.

Table 1: Summary of Test Power Factor and X/R Values for LV Devices.

Device pf X/R Ratio Power circuit breaker, unfused 0.15 6.591 Power circuit breaker, fused 0.20 4.899

Molded case breaker, interrupting rating greater than 20000 A 0.15-0.20 6.591-4.899

Molded case breaker, interrupting rating 10001 to 20000 A 0.25-0.30 3.9-3.18

Molded case breaker, interrupting rating 10000 A and less 0.45-0.50 2.0-1.732

For power circuit breakers, the power factors are taken from ANSI/IEEE C37.13. For molded case breakers, the power factors are taken from NEMA standard AB1. Since the NEMA standard specifies a range of test circuit power factors, the highest value (lowest X/R ratio) is used to determine the multiplying factor. This produces the most conservative (largest) factor.

The included one-line diagrams are a simplified version of the system drawings, showing only those parts of the electrical system under consideration. The various circuit locations on the diagrams have been labeled with bus identification numbers so input data could be supplied to the computer and the computer output could be readily interpreted.

2.2 Data Used in the Calculations

2.2.1 Power Company Data

Customer has advised that their existing system is capable of delivering a maximum available three-phase short-circuit current of 10,135A at 13.2kV with an X/R ratio of 13.7. These values determined the starting point for the analysis.

2.2.2 Cable Data

The "FEEDER INPUT DATA" computer printouts list the conductor (cable and/or busway) data used for each circuit segment. Included are lengths, number per phase, size, conductor material, cable insulation type, conduit material and resistance and reactance values. Also, conductor lengths, number per phase, and size and conductor material are recorded on the one-line diagrams.

Resistance values are based on 25 degrees Celsius (room temperature) rather than the full load temperature usually shown in descriptive literature since short-circuits can occur when the circuit is initially energized or lightly loaded as well as when fully loaded. The resistance and reactance values are typical values obtained from a study of data from various conductor manufactures.

Values are tabulated according to whether several single conductors or one multiple conductor is used and whether the conduit is steel, aluminum or plastic.

2.2.3 Transformer Data

Square D transformer percent impedance and typical X/R ratio values were used for all transformers. The exact R and X component values used are shown on the "TRANSFORMER INPUT DATA" printouts.

2.2.4 Motor Contribution To Short-Circuit Current

Motor contribution to the short-circuit current is taken into account in this short-circuit analysis.

During the first few cycles of a fault, running motors act as generators and produce a current which will combine with the source short-circuit current flowing to the fault as illustrated in Figure 1. Sources may be, but are not limited to, the Power Company, local generators, or both.

Figure 1: Example motor contribution.

Connected motors shown on the study one-line were assumed to be running at the time of the fault. Motors fed by adjustable speed drives equipped with bypass contactors were considered to contribute to system fault currents as well. However, motors fed by drives without bypass contactors were not considered since they do not contribute to fault current. Redundant motors shown on the study one-line were also assumed to be running at the time of the fault unless operating controls prohibit these conditions.

A motor’s contribution to a fault at its terminals is equal to the full-load ampere (FLA) rating of the motor divided by its per-unit subtransient reactance, similar to the contribution from a generator. However, at the upstream switchboard, panelboard, or motor-control center, the fault contribution from the individual motors is reduced by the impedance of the motor branch circuit conductors. Since data on motor subtransient reactances and branch-circuit conductor lengths is often difficult to obtain, assumptions regarding the motors’ subtransient reactances are typically made when the system model is built.

For calculation of low-voltage fault duty, the contribution from induction motors and synchronous motors in the system are considered. For small induction motors (less than 50 hp) where the impedance of the installation (i.e., motor and conductor) is not known, an equivalent subtransient reactance of 0.25 pu, resulting in a fault contribution of 4 times rated current, is assumed. Larger motors (50 hp and above) have an assumed subtransient reactance of 0.2 pu, resulting in a fault contribution of 5 times rated current. This is consistent with recommendations in IEEE Std. 141, IEEE Recommended Practice for Electric Power Distribution for Industrial Plants (the IEEE Red Book).

If applicable, multiplying factors are adjusted per Table 7 of ANSI/IEEE C37.010, IEEE Application Guide for AC High-Voltage Circuit Breakers Rated on a Symmetrical Current Basis for medium/high voltage fault duty. The table also shows contributions from induction motors less than 50 hp to be neglected.

The motor short-circuit contribution is determined and included in the computer short-circuit analysis so that the results should represent the highest short-circuit current to which the equipment might be subjected.

Unless otherwise indicated in the "CONTRIBUTION DATA" computer printouts, some motor loads are modeled as lumped induction motors connected directly to the low voltage buses using the recommended subtransient reactance values from C37.010, C37.13, and IEEE Std. 141. These modeled values appear on the "CONTRIBUTION DATA" and the "FAULT REPORT" computer printouts.

2.2.5 Assumptions

Some assumptions for input data were required and may affect the results of this study. In general, assumptions are needed because of lack of documentation. Significant differences between the assumptions listed here and actual values will require that this power system analysis be revised.

The following assumptions were made:

1. The available short-circuit current provided, see appendix, was assumed to be at the point of connection to the existing system.

2.3 Short-Circuit Analysis Results and Recommendations

After making the calculations, the distribution equipment was checked to determine its adequacy to interrupt or withstand the effects of the calculated maximum short-circuit current at its location.

For some solidly-grounded systems, like close-coupled unit substations and generator gear, it is possible the bolted three-phase fault current is not the maximum fault current. The power systems engineer performing the study considered applicable buses and has reported bolted line-to-ground fault current when required. The results are listed in the "SHORT-CIRCUIT EVALUATION

TABLE".

Short-circuit case description: Existing utility and generators connected. SB-3S1 and SB-4S1 mains and ties all closed.

Listed in the tables are the calculated short-circuit currents at each piece of equipment and the ratings of the lowest rated device in the equipment enclosure. Comparing the two sets of values shows that all of the equipment examined is either adequate by itself or when used in series with another circuit breaker or protected by a line side current-limiting fuse or circuit breaker.

The short-circuit evaluation table lists some equipment that was not evaluated because the equipment’s rating could not be determined at the time of study preparation. These are identified by note number ‘1’ in the far right hand column of the table. The study recommends a field evaluation of this equipment by the customer to verify the equipment’s short-circuit current rating is greater than the calculated fault duty which can be evaluated by referring to the short-circuit output report. For each bus modeled, that report contains evaluations for UL and ANSI equipment and if necessary Schneider Electric Engineering Services, LLC can assist in this evaluation.

Input data and short-circuit output data pages are included in separate appendices.

2.4 Short-Circuit Evaluation Table

SQUARE D ENGINEERING SERVICES REFER TO DRAWINGS: D-ML-10-357-1, -2

EQUIP. DESCRIPTION LOWEST RATED DEVICE MAXIMUM LINE SIDE LINE SIDE

BUS PER SYSTEM ONE NOMINAL IN EQUIPMENT ENCLOSURE AVAILABLE X/R MAXIMUM SERIES NOTES NO. LINE DIAGRAM(S) L-L VOLTS TYPE AIC OR WCR SCA OR DUTY RATIO DEVICE RATING EVALUATION # 002 SG-4A 13200.0 DIN 30E/HVL 65,000 9,643 5.251 Adequate 003 SG-3A 13200.0 DIN 30E/HVL 65,000 8,999 3.349 Adequate 005 SG-4B 13200.0 DIN 30E/HVL 65,000 9,643 5.248 Adequate 006 SG-3B 13200.0 DIN 30E/HVL 65,000 8,998 3.347 Adequate

010A SB-4S1 480.0 JJ 65,000 23,667 3.221 Adequate 010B SB-4S1 480.0 JJ 65,000 23,667 3.221 Adequate 011 PFCC-4A 480.0 SCCR42 42,000 21,984 2.633 Adequate 012 DP-4M3 480.0 FH(3P) 25,000 21,319 2.939 Adequate 013 4PA 480.0 EDB(3P) 18,000 16,755 2.533 Adequate 014 4PB 480.0 EGB(3P) 35,000 16,971 2.550 Adequate 015 DP-4D1 480.0 FH(3P) 25,000 21,323 2.940 Adequate 016 PFCC-4B 480.0 SCCR42 42,000 21,984 2.633 Adequate 019 4LN 208.0 QOB 10,000 5,211 0.639 Adequate 023 DP-4D6 208.0 FA(3P) 25,000 6,965 2.060 Adequate 024 4LG 208.0 QOB 10,000 2,434 0.573 Adequate 025 4LH 208.0 QOB 10,000 2,751 0.623 Adequate 026 4LK 208.0 QOB 10,000 3,224 0.701 Adequate 027 4LL 208.0 QOB 10,000 3,030 0.668 Adequate 028 4LM 208.0 QOB 10,000 6,326 1.615 Adequate 031 DP-4D4 208.0 FA(3P) 25,000 7,031 2.110 Adequate 032 4LC 208.0 QOB 10,000 2,445 0.575 Adequate 033 4LD 208.0 QOB 10,000 2,765 0.624 Adequate 034 4LF 208.0 QOB 10,000 2,619 0.601 Adequate 035 4LA 208.0 QOB 10,000 2,223 0.542 Adequate 036 4LB 208.0 QOB 10,000 2,329 0.557 Adequate

041A SB-3S1 480.0 JJ 65,000 23,582 3.260 Adequate 041B SB-3S1 480.0 JJ 65,000 23,582 3.260 Adequate 042 3PA 480.0 EDB(3P) 18,000 16,544 2.545 Adequate 043 DP-3M3 480.0 FH(3P) 25,000 19,933 2.826 Adequate 047 DP-3D6 208.0 FA(3P) 25,000 6,923 2.073 Adequate 048 3LG 208.0 QOB 10,000 2,472 0.582 Adequate 049 3LH 208.0 QOB 10,000 2,747 0.625 Adequate 050 3LK 208.0 QOB 10,000 3,288 0.717 Adequate 051 3LL 208.0 QOB 10,000 3,025 0.671 Adequate 052 3LM 208.0 QOB 10,000 5,380 1.227 Adequate

SHORT-CIRCUIT

EVALUATION TABLE

#N/A = Number not available.

SCET Page 1 of 2 [Form Ver. 2.12]

SQUARE D ENGINEERING SERVICES REFER TO DRAWINGS: D-ML-10-357-1, -2

EQUIP. DESCRIPTION LOWEST RATED DEVICE MAXIMUM LINE SIDE LINE SIDE

BUS PER SYSTEM ONE NOMINAL IN EQUIPMENT ENCLOSURE AVAILABLE X/R MAXIMUM SERIES NOTES NO. LINE DIAGRAM(S) L-L VOLTS TYPE AIC OR WCR SCA OR DUTY RATIO DEVICE RATING EVALUATION #

SHORT-CIRCUIT

EVALUATION TABLE

053 PFCC-3A 480.0 SCCR42 42,000 21,395 2.516 Adequate 054 3PB 480.0 EDB(3P) 18,000 16,366 2.536 Adequate 057 3LN 208.0 QOB 10,000 5,163 0.640 Adequate 058 DP-3D1 480.0 FH(3P) 25,000 20,577 2.895 Adequate 061 DP-3D4 208.0 FA(3P) 25,000 6,912 2.059 Adequate 062 3LC 208.0 QOB 10,000 2,600 0.602 Adequate 063 3LD 208.0 QOB 10,000 2,904 0.651 Adequate 064 3LF 208.0 QOB 10,000 2,744 0.625 Adequate 065 3LA 208.0 QOB 10,000 2,243 0.547 Adequate 066 3LB 208.0 QOB 10,000 2,429 0.575 Adequate 067 PFCC-3B 480.0 SCCR42 42,000 21,394 2.515 Adequate 068 LW 480.0 EDB(3P) 18,000 12,832 1.334 Adequate

069 LP 208.0 #N/A 2,114 0.528 #N/A (1)

(1) SHORT-CIRCUIT AIC OR WCR IS UNKNOWN AT THESE LOCATIONS AND NEEDS TO BE CHECKED TO ENSURE EQUIPMENT ADEQUACY.

#N/A = Number not available.

SCET Page 2 of 2 [Form Ver. 2.12]

3 OVERCURRENT DEVICE COORDINATION ANALYSIS

3.1 General Procedure

An overcurrent device time-current coordination analysis is an organized effort to determine the settings and, where appropriate, the ampere ratings and types for the over-current protective devices in an electrical system. The objective of the coordination analysis is to effect a time-current coordination among the devices, thereby achieving the desired system protection and electrical service continuity goals.

Maximum protection requires that the overcurrent protective devices be rated, selected, and adjusted to allow the normal load currents to flow while instantaneously opening the circuit when abnormal currents flow.

However, maximum service continuity requires that the overcurrent protective devices be rated, selected, and adjusted so that only the overcurrent protective device nearest the fault opens and isolates the faulted circuit from the system, permitting the rest of the system to remain in operation. Protective devices farther from the fault location should therefore essentially act as backup protection for the devices nearer to the fault, allowing the fault to be cleared with a minimum of disruption to the system. This is referred to as “selective coordination” between the protective devices. This may allow longer duration faults when the fault point is nearer the service entrance; however, such faults are not as common, and setting the protective devices to operate in this manner is generally more desirable than deenergizing most or all of the system for a fault near one of the loads.

Selecting and setting the overcurrent devices is a procedure where the time-current characteristic curves of the various devices in series are compared with one another on a log-log graph. This procedure should take into account boundaries defined by load currents, short-circuit currents, and ANSI and NEC requirements.

Selective coordination usually will be obtained when the log-log plots of time-current characteristics show sufficient clear space or no overlap between the curves for the protective devices operating in series. Coordination will often stop short of complete selectivity when an acceptable compromise is reached between the various boundaries imposed on the selecting and setting procedure.

The CAPTOR module of the SKM Power*Tools software was used to complete the device coordination analysis. As shown on the one-line diagrams, each overcurrent protective device or motor under consideration by the program has been assigned an identification number so that the computer output could be readily interpreted.

3.2 Specific Procedure

3.2.1 Short-Circuit Current Considerations

All protective device characteristic curves shown on the time-current graphs end at the calculated maximum short-circuit current at that device.

3.2.2 Molded Case Breaker Coordination

A molded case circuit breaker will trip with no intentional time delay for short-circuit currents above its instantaneous trip setting. Because of this, molded case breakers in series can only be selectively coordinated with each other if there is sufficient impedance between them so that the maximum available short-circuit current at the downstream breaker is less than the instantaneous trip setting of the upstream breaker. In Figure 2, breaker “C” illustrates this principle.

Figure 2: Example molded case breaker coordination.

There is enough cable impedance to limit the maximum available short-circuit current at “C” to less than the instantaneous trip setting of either “A” or “B”. When molded case breakers are in series without sufficient impedance between them to permit complete coordination, e.g., a panel main breaker and one of the branch devices in the panel, the time-current curves will overlap in the high-current instantaneous trip region. This is illustrated by the overlap between the curves for devices “A” and “B” in Figure 2. Most molded case breakers exhibit some degree of current limitation that will often result in selective operation in the overlap region. Time-current coordination curves included in this report do not match the results from Square D’s data bulletin (0100DB0501R3). The software used to generate the curves is incapable of accounting for the dynamic impedance the system has when two or more devices in series “see” a fault. The data bulletin takes the dynamic impedance introduced by the downstream device into account. Greater separation between the instantaneous settings may increase the likelihood that the two devices will operate selectively. The potential lack of coordination is generally not considered critical and can be avoided only by adopting a different and, in general, less economically practical design especially when the following are considered:

• Most faults occur in equipment such as motors, lighting panels, and process control panels which typically are located at the end of branch circuits, significantly reducing fault level and thereby reducing or eliminating the possibility of non-selective operation.

• Lower magnitude arcing faults in rotating machinery and lighting panels are statistically more common than bolted three-phase faults.

• Ground faults are more common than three-phase faults.

• Maximum fault current is a random event depending on point-on-wave of the fault occurrence and other factors.

• The device cutoff points on time-current coordination graphs are based on bolted fault current levels which correspond to zero impedance. Typical fault current impedance is usually greater than zero so the actual fault current seen by overcurrent devices can be less than what is shown on the time-current coordination graphs.

Recommended breaker trip settings are given in the "OVERCURRENT DEVICE SETTING

TABLE – LV CIRCUIT BREAKERS".

3.2.3 Low-Voltage Ground Fault Relay Settings

The main ground fault time setting was chosen to selectively coordinate with the appropriate load side devices. The ground fault current pickup setting was chosen at maximum for best selective coordination.

Selective coordination with downstream breakers does not exist for any ground fault current exceeding this maximum pickup setting but less than the magnetic setting of the load side breaker.

This is unavoidable because the load side protective devices are not equipped with ground fault protection. Figure 3 illustrates this.

Figure 3: Example ground fault coordination (current scale X 10).

As shown in Figure 3, the main ground fault device A does not selectively coordinate with feeder breaker B for ground fault currents in the range of 535A-1,330A as indicated.

All ground fault settings are tabulated in the appropriate overcurrent device setting tables.

3.2.4 Transformer Protective Devices

If in the project scope, medium- and/or low-voltage transformer primary overcurrent protective devices were checked for compliance with NEC Article 450. Also, medium voltage protective devices, primary, secondary and secondary feeder, were evaluated with respect to the applicable ANSI/IEEE Through Fault Guides (C57.12.59 for dry and cast resin type and C57.109 for liquid immersed type) and the Appendix for ANSI/IEEE C37.91. Transformer standards define low-voltage transformers as having a primary voltage less than or equal to 600V. Transformer full load currents and magnetizing inrush currents were also considered.

To evaluate through fault protection according to the ANSI Guides, the applicable curve was plotted representing a transformer's projected damage threshold for the cumulative effects of through faults. However, this ANSI through fault curve must be reduced for certain unbalanced secondary faults, because even though full short-circuit current is flowing in one or more secondary windings, the primary overcurrent device experiences less current.

Secondary line-to-neutral faults on delta-wye connected transformers produce only 0.577 of the maximum 3-phase fault current in the primary overcurrent device while one secondary winding experiences the full short-circuit current as illustrated in Figure 4 below. Therefore, to account for this fault condition, the ANSI through fault curve has been adjusted by a factor of 0.577. Both curves (three phase line-to-line and single phase line-to-neutral) are plotted on the time-current graphs.

Figure 4: Delta–Wye 3-PH and L-N fault current per unit values.

Since the through fault curves represent a transformer's projected damage threshold for the cumulative mechanical and thermal effects of through faults, all applicable primary and secondary overcurrent devices were checked to ensure interruption before these through fault curves were reached.

Further, to avoid nuisance interruptions, the primary overcurrent devices were also checked to ensure they will carry the transformers rated full load and equivalent magnetic inrush currents which are plotted on the time-current graphs.

Because of the restrictions mentioned above, complete selective coordination between the transformer primary and secondary main devices may not exist for any transformers examined as shown by the overlapping of their characteristics on the time-current graphs. However, this is judged acceptable, because the opening of either device results in the same extent of service interruption.

3.2.5 Cable Protection

Feeder overcurrent protective devices were reviewed to verify the protection of their load side cables as shown on the one-line diagrams in accordance with NEC Article 240. If the adjustable low-voltage protective devices are set as suggested in this report, then the cables reviewed will be properly protected.

If applicable, a cable short-circuit withstand line is drawn on some time-current graphs for medium-voltage cables. The line is drawn from ICEA Publication P-32-382. Medium-voltage overcurrent devices were set to interrupt before this cable withstand is reached.

However, the above analysis does not include any aspects of cable ampacity adjustment factors such as derating for conduit fill, elevated ambient temperature, and so on allowed by the NEC.

3.2.6 Selective Coordination and the 2008 NEC

In some situations, even though individual devices are not coordinated, the system may still be considered to be well-coordinated. For example, where two devices are in series with no loads connected between them, operation of either/both devices interrupts power to the exact same portion of the power system. The system may be considered to be coordinated even though the two devices, strictly speaking, do not coordinate with one another.

Selective coordination, while always desirable, is not required by the NEC except in certain situations:

• In health-care facilities, per NEC 517.17(C): “Ground-fault protection for operation of the service and feeder disconnecting means shall be fully selective such that the feeder device, but not the service device, shall open on ground faults on the load side of the feeder device.”

• In elevator circuits when more than one elevator motor is fed by a single feeder. See

NEC 620.62.

• In emergency and legally-required standby power systems (including those in hospitals and other health-care facilities where so required), per NEC 700.27 and NEC 701.18.

The requirements for selective coordination in emergency and legally-required standby systems, call for each overcurrent device to be “selectively coordinated with all supply side overcurrent protective devices.” This requirement can be problematic for system designers because it recognizes only device coordination and not system coordination. Special consideration of selective coordination (beyond the traditional coordination study) must be given when the system is initially designed, since for both fusible and circuit-breaker based systems, designs that are otherwise NEC compliant may not meet the selective coordination requirements of the NEC.

Compliance with NEC articles 517.17 (Health Care Facilities), 700.27 (Emergency Systems), and

701.18 (Legally Required Standby Systems) may require interpretation and approval by the local authority having jurisdiction.

3.3 Analysis of Results and Recommendations

The basic results of an overcurrent device coordination analysis are the time-current coordination graphs which are plotted to illustrate the degree of selective coordination achieved in the system.

Eleven graphs are included in this report. Settings for all devices which have adjustable characteristics are summarized in the appropriate overcurrent device setting tables. Smaller devices with fixed time-current characteristics are not shown on the graphs unless they directly affect the setting of an adjustable upstream device.

To generate the time-current graphs, a computer program was used which allows the power system engineer to determine optimum coordination, after first insuring that loading and protection requirements are satisfied. The engineer’s objective is to determine the best coordination for the entire system. This approach necessitates tradeoffs in selectivity for some parts of the system to achieve maximum coordination in more critical areas. Regions in which coordination has been sacrificed are as previously discussed involving transformer primary and secondary main devices, high current regions of molded case breakers, etc.

3.3.1 TCC Plot Remarks

The following comments refer to the graphs shown in the Time Current Coordination Graphs section of this report.

Time-current coordination graph 001.tcc shows the primary and secondary devices of transformer T-DP-4D6. As shown by the graph, the maximum equivalent magnetic inrush point lies within the operating band of the primary breaker. This indicates the possibility of this breaker occasionally tripping on transformer energization if this "worst case" inrush current is produced. This situation is only noted here so that any nuisance tripping which should occur may be correctly diagnosed as such. A similar situation exists on time-current coordination graphs 004.tcc, 008.tcc, 009.tcc and for transformer T-DP-3D6.

Time-current coordination graph 002.tcc shows device numbers 010-03 and 012-02 as well as other devices. As shown by the graph, these devices overlap in the low current region. If this is not acceptable, circuit breakers with electronic trip units may need to be considered. A similar situation exists on time-current coordination graphs 009.tcc and 011.tcc.

Time-current coordination graph 002.tcc shows device numbers 002-01 and 010-03 as well as other devices. As shown by the graph, these devices overlap. To improve coordination, consider changing the transformer primary fuse to 50A which would provide less transformer protection but reduce the chance of the fuse interrupting a fault on the load side of a switchboard feeder breaker. A similar situation exists for fuse on transformers T-4B, T-3A and T-3B.

Time-current coordination graph 003.tcc shows device numbers 001-01 and 002-01 as well as other devices. Although outside the scope of this study, the existing GE Multilin relay, device 001-01, has an instantaneous function set to 3600A. It should be noted that a fault on the load side of device 002-01, transformer primary fuse, could trip both the upstream breaker and transformer primary fuse for a high current fault. Ground fault settings for the GE Multilin relay were not provided and could not be reviewed.

Time-current coordination graph 007.tcc shows device numbers 010-01A and 010-01T. These devices do not coordinate. However, these devices are sized at the same trip level so this situation is unavoidable.

3.4 Overcurrent Device Setting Table

DEVICE SETTING TABLE Ames, IA

SQUARE D ENGINEERING SERVICES LV CIRCUIT BREAKERS REFER TO DRAWINGS: D-ML-10-357-1, -2

FRAME

DEVICE NUMBER & NAME MANUFACTURER BUS VOLTS SENSOR

BUS NUMBER & NAME DEVICE TYPE DESCRIPTION DEV. VOLTS PLUG SETTINGS

010A SB-4S1 010-01A SB-4S1 MAIN A SQUARE D 480.0V 800.0A Phase

Static Trip Masterpact NW, 5.0 & 6.0 A/P/H 600V 800.0A LTPU (A);LTD (A 0.4-1.0 x S) 1 (800A); 12

LSI, 400-6000AS, UL A STPU 8 (6400A)

STD 0.1 (I^2t Out)

INST (NW**N) 8 (6400A)

Ground Ig (0.2-1.0 x S) J (800A) tg (0-0.4) 0.2 (I^2t Out)

010B SB-4S1 010-01B SB-4S1 MAIN B SQUARE D 480.0V 800.0A Phase Static Trip Masterpact NW, 5.0 & 6.0 A/P/H 600V 800.0A LTPU (A);LTD (A 0.4-1.0 x S) 1 (800A); 12

LSI, 400-6000AS, UL A STPU 8 (6400A)

STD 0.1 (I^2t Out)

INST (NW**N) 8 (6400A)

Ground

Ig (0.2-1.0 x S) J (800A) tg (0-0.4) 0.2 (I^2t Out)

010A SB-4S1 010-01T SB-4S1 TIE SQUARE D 480.0V 800.0A Phase Static Trip Masterpact NW, 5.0 & 6.0 A/P/H 600V 800.0A LTPU (A);LTD (A 0.4-1.0 x S) 1 (800A); 12

LSI, 400-6000AS, UL A STPU 8 (6400A)

STD 0.1 (I^2t Out)

INST (NW**N) 8 (6400A)

Ground

Ig (0.2-1.0 x S) J (800A) tg (0-0.4) 0.2 (I^2t Out)

010A SB-4S1 010-02 4PA SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LC 600V 400.0A INST LO (2000A)

300-600A

010A SB-4S1 010-03 DP-4M3 SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LC 600V 400.0A INST HI (3200A)

300-600A

010A SB-4S1 010-04 PFCC-4A SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JJ 600V 200.0A Im HI (2000A)

150-250A

010B SB-4S1 010-05 4PB SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LC 600V 400.0A INST LO (2000A)

300-600A

Frame, Sensor and Plug types must be verified to agree with this list prior to installing settings. I2t dial settings follow In = On and Out = Off.

LVCB - Page 1 of 4

[Form Ver. 2.9]

SQUARE D ENGINEERING SERVICES LV CIRCUIT BREAKERS REFER TO DRAWINGS: D-ML-10-357-1, -2

FRAME

DEVICE NUMBER & NAME MANUFACTURER BUS VOLTS SENSOR

BUS NUMBER & NAME DEVICE TYPE DESCRIPTION DEV. VOLTS PLUG SETTINGS

010B SB-4S1 010-06 DP-4D1 SQUARE D 480.0V 400.0A Thermal Curve

Thermal Magnetic LC 600V 400.0A INST HI (3200A) 300-600A

010B SB-4S1 010-07 PFCC-4B SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JJ 600V 200.0A Im HI (2000A)

150-250A

010B SB-4S1 010-08 LW SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JJ 600V 225.0A Im HI (2250A)

150-250A

012 DP-4M3 012-02 T-DP-4D6 SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JG 600V 175.0A Im HI (1750A)

150-250A

013 4PA 013-01 4PA MAIN SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LA (10/04) 600V 400.0A INST (LO-HI) LO (2000A)

125-400A, 2-3 poles

014 4PB 014-01 4PB MAIN SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LH (10/04) 600V 400.0A INST (LO-HI) LO (2000A)

125-400A, 2-3 poles

023 DP-4D6 023-01 DP-4D6 MAIN SQUARE D 208.0V 400.0A Thermal Curve Thermal Magnetic LA (10/04) 600V 400.0A INST (LO-HI) HI (4000A)

125-400A, 2-3 poles

031 DP-4D4 031-01 DP-4D4 MAIN SQUARE D 208.0V 400.0A Thermal Curve Thermal Magnetic LA (10/04) 600V 400.0A INST (LO-HI) 3 (3088A)

125-400A, 2-3 poles

041A SB-3S1 041-01A SB-3S1 MAIN A SQUARE D 480.0V 800.0A Phase Static Trip Masterpact NW, 5.0 & 6.0 A/P/H 600V 800.0A LTPU (A);LTD (A 0.4-1.0 x S) 1 (800A); 12

LSI, 400-6000AS, UL A STPU 8 (6400A)

STD 0.1 (I^2t Out)

INST (NW**N) 8 (6400A)

Ground

Ig (0.2-1.0 x S) J (800A) tg (0-0.4) 0.2 (I^2t Out)

Frame, Sensor and Plug types must be verified to agree with this list prior to installing settings. I2t dial settings follow In = On and Out = Off.

LVCB - Page 2 of 4

SQUARE D ENGINEERING SERVICES LV CIRCUIT BREAKERS REFER TO DRAWINGS: D-ML-10-357-1, -2

FRAME

DEVICE NUMBER & NAME MANUFACTURER BUS VOLTS SENSOR

BUS NUMBER & NAME DEVICE TYPE DESCRIPTION DEV. VOLTS PLUG SETTINGS

041B SB-3S1 041-01B SB-3S1 MAIN B SQUARE D 480.0V 800.0A Phase

Static Trip Masterpact NW, 5.0 & 6.0 A/P/H 600V 800.0A LTPU (A);LTD (A 0.4-1.0 x S) 1 (800A); 12

LSI, 400-6000AS, UL A STPU 8 (6400A)

STD 0.1 (I^2t Out)

INST (NW**N) 8 (6400A)

Ground Ig (0.2-1.0 x S) J (800A) tg (0-0.4) 0.2 (I^2t Out)

041A SB-3S1 041-01T SB-3S1 TIE SQUARE D 480.0V 800.0A Phase Static Trip Masterpact NW, 5.0 & 6.0 A/P/H 600V 800.0A LTPU (A);LTD (A 0.4-1.0 x S) 1 (800A); 12

LSI, 400-6000AS, UL A STPU 8 (6400A)

STD 0.1 (I^2t Out)

INST (NW**N) 8 (6400A)

Ground

Ig (0.2-1.0 x S) J (800A) tg (0-0.4) 0.2 (I^2t Out)

041A SB-3S1 041-02 3PA SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LC 600V 400.0A INST LO (2000A)

300-600A

041A SB-3S1 041-03 DP-3M3 SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LC 600V 400.0A INST HI (3200A)

300-600A

041A SB-3S1 041-04 PFCC-3A SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JJ 600V 200.0A Im HI (2000A)

150-250A

041B SB-3S1 041-05 3PB SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LC 600V 400.0A INST LO (2000A)

300-600A

041B SB-3S1 041-06 DP-3D1 SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LC 600V 400.0A INST HI (3200A)

300-600A

041B SB-3S1 041-07 PFCC-3B SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JJ 600V 200.0A Im HI (2000A)

150-250A

Frame, Sensor and Plug types must be verified to agree with this list prior to installing settings. I2t dial settings follow In = On and Out = Off.

LVCB - Page 3 of 4

SQUARE D ENGINEERING SERVICES LV CIRCUIT BREAKERS REFER TO DRAWINGS: D-ML-10-357-1, -2

FRAME

DEVICE NUMBER & NAME MANUFACTURER BUS VOLTS SENSOR

BUS NUMBER & NAME DEVICE TYPE DESCRIPTION DEV. VOLTS PLUG SETTINGS

042 3PA 042-01 3PA MAIN SQUARE D 480.0V 400.0A Thermal Curve

Thermal Magnetic LA (10/04) 600V 400.0A INST (LO-HI) LO (2000A) 125-400A, 2-3 poles

043 DP-3M3 043-02 T-DP-3D6 SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JG 600V 175.0A Im HI (1750A)

150-250A

047 DP-3D6 047-01 DP-3D6 MAIN SQUARE D 208.0V 400.0A Thermal Curve Thermal Magnetic LA (10/04) 600V 400.0A INST (LO-HI) HI (4000A)

125-400A, 2-3 poles

054 3PB 054-01 3PB MAIN SQUARE D 480.0V 400.0A Thermal Curve Thermal Magnetic LA (10/04) 600V 400.0A INST (LO-HI) LO (2000A)

125-400A, 2-3 poles

061 DP-3D4 061-01 DP-3D4 MAIN SQUARE D 208.0V 400.0A Thermal Curve Thermal Magnetic LA (10/04) 600V 400.0A INST (LO-HI) 3 (3088A)

125-400A, 2-3 poles

068 LW 068-01 LW MAIN SQUARE D 480.0V 250.0A Thermal Curve Thermal Magnetic JD 600V 225.0A Im HI (2250A)

150-250A

Frame, Sensor and Plug types must be verified to agree with this list prior to installing settings. I2t dial settings follow In = On and Out = Off.

LVCB - Page 4 of 4

3.5 Time-Current Coordination Graphs - Recommended Settings

TX Inrush

T-DP-4D6

0.

0.

0.

0.

0.

0.

1K 1K

2K 2K

4K 4K

6K 6K

8K 8K

K

K

0.01 0.01

0.02 0.02

0.04 0.04

0.06 0.06

0.08 0.08

0.10 0.10

0.20 0.20

0.40 0.40

0.60 0.60

0.80 0.80 1 1

2 2

4 4

6 6

8 8 10 10

20 20

40 40

60 60

80 80 100 100

200 200

400 400

600 600

800 800 1000 1000

CURRENT IN AMPERES

TIM

E

IN

S

E C

O N

D S

Name: 023-06 4LM Manufacturer: SQUARE D Type: FA Frame/Model: FA Trip: 100.0 A Voltage: 208.0 V Settings: Phase Fixed

Name: 023-01 DP-4D6 MAIN Manufacturer: SQUARE D Type: LA (10/04) Frame/Model: LA Trip: 400.0 A Voltage: 208.0 V Settings: Phase Thermal Curve

INST (LO-HI) HI (4000A)

Name: 012-02 T-DP-4D6 Manufacturer: SQUARE D Type: JG Frame/Model: JG Trip: 175.0 A Voltage: 480.0 V Settings: Phase Thermal Curve Im HI (1750A)

Name: T-DP-4D6 Nominal kVA: 112.5 kVA Pri Voltage: 480 V Sec Voltage: 208 V Z = 3.6900 % InrushFactor 15.0

Name: 023-06 4LM Manufacturer: SQUARE D Type: FA Frame/Model: FA Trip: 100.0 A Voltage: 208.0 V Settings: Phase Fixed

Name: 023-01 DP-4D6 MAIN Manufacturer: SQUARE D Type: LA (10/04) Frame/Model: LA Trip: 400.0 A Voltage: 208.0 V Settings: Phase Thermal Curve

INST (LO-HI) HI (4000A)

Name: 012-02 T-DP-4D6 Manufacturer: SQUARE D Type: JG Frame/Model: JG Trip: 175.0 A Voltage: 480.0 V Settings: Phase Thermal Curve Im HI (1750A)

Name: T-DP-4D6 Nominal kVA: 112.5 kVA Pri Voltage: 480 V Sec Voltage: 208 V Z = 3.6900 % InrushFactor 15.0

Name: 001.tcc Current Scale x 100 Reference Voltage: 208

October 12, 2010 ML10357 USDA NATIONAL ANIMAL DISEASE CENTER Square D

0.

0.

0.

0.

0.

0.

1K 1K

2K 2K

4K 4K

6K 6K

8K 8K

K

K

0.01 0.01

0.02 0.02

0.04 0.04

0.06 0.06

0.08 0.08

0.10 0.10

0.20 0.20

0.40 0.40

0.60 0.60

0.80 0.80 1 1

2 2

4 4

6 6

8 8 10 10

20 20

40 40

60 60

80 80 100 100

200 200

400 400

600 600

800 800 1000 1000

CURRENT IN AMPERES

TIM

E

IN

S

E C

O N

D S

Name: 012-02 T-DP-4D6 Manufacturer: SQUARE D Type: JG Frame/Model: JG Trip: 175.0 A Voltage: 480.0 V Settings: Phase Thermal Curve Im HI (1750A)

Name: 010-03 DP-4M3 Manufacturer: SQUARE D Type: LC Frame/Model: LC Trip: 400.0 A Voltage: 480.0 V Settings: Phase Thermal Curve

INST HI (3200A)

Name: 010-01A SB-4S1 MAIN A Manufacturer: SQUARE D Type: Masterpact NW, 5.0 & 6.0 A/P/H Frame/Model: NW08N Trip: 800.0 A Voltage: 480.0 V Settings: Phase LTPU (A);LTD (A 0.4-1.0 x S) 1 (800A); 12

STPU 8 (6400A)

STD 0.1 (I^2t Out)

INST (NW**N) 8 (6400A)

Name: 002-01 SG-4A Manufacturer: SQUARE D Type: 15.5KV DIN Frame/Model: 30 Trip: 30.0 A Voltage: 13200.0 V Settings: Phase Opening Clearing Curve

Name: 012-02 T-DP-4D6 Manufacturer: SQUARE D Type: JG Frame/Model: JG Trip: 175.0 A Voltage: 480.0 V Settings: Phase Thermal Curve Im HI (1750A)

Name: 010-03 DP-4M3 Manufacturer: SQUARE D Type: LC…