Carroll University Science Building BP3
SECTION 26-0573 - SHORT CIRCUIT/COORDINATION STUDY AND ARC FLASH HAZARD STUDY
PART 1 – GENERAL
1.01
A.
B.
C.
D.
E.
F.
1.02
A.
B.
C.
1.03
A.
B.
C.
D.
E.
F.
G.
H.
I.
J.
K.
1.04
A.
B.
SCOPE OF WORK
Base Bid: The electrical contractor shall retain the services of an independent third party firm to perform a short
circuit/coordination study and arc flash hazard study as described herein.
The preliminary studies shall be submitted to the Design Engineer prior to receiving final approval of the
distribution equipment shop drawings and/or prior to release of equipment for manufacture. If formal
completion of the studies may cause delay in equipment manufacture, approval from the Engineer may be
obtained for a preliminary submittal of sufficient study data to ensure that the selection of device ratings and
characteristics will be satisfactory. The preliminary studies shall be revised and final study resubmitted following
installation of conductors and equipment.
The studies shall include all portions of the electrical distribution system from the normal power source or
sources, and emergency / standby sources, down to and including the smallest circuit breaker in the distribution
system (for short circuit calculations). Normal system connections and those which result in maximum fault
conditions shall be adequately covered in the study.
The firm should be currently involved in high- and low-voltage power system evaluation. The study shall be
performed, stamped and signed by a registered professional engineer in the State of Wisconsin (WI). Credentials
of the individual(s) performing the study and background of the firm shall be submitted to the Design Engineer
for approval prior to start of the work. A minimum of five (5) years’ experience in power system analysis is
required for the individual in charge of the project.
The firm performing the study should demonstrate capability and experience to provide assistance during start
up as required.
The study and assessment shall be performed based on SKM’s systems analysis and PowerTool for Windows
(PTW) software program.
SECTION INCLUDES
Short Circuit and Coordination Study
Field Settings
Arc Flash Hazard Study
RELATED WORK
Drawings and general provisions of the Contract, including General and Supplementary Conditions and Division
01 Specification Sections, apply to this Section.
Section 26 11 16 – Secondary Unit Substation
Section 26 12 16 – Dry-Type, Medium-Voltage Transformer
Section 26 13 02 – Medium-Voltage Pad Mounted Switchgear
Section 26 14 13 - Switchboards
Section 26 24 16 – Panelboards
Section 26 27 28 – Disconnect Switches
Section 26 28 16 – Enclosed Switches and Circuit Breakers
Section 26 29 00 – Low-Voltage Controllers
Section 26 29 23 – Variable Frequency Drives
Section 26 36 00 – Transfer Switches
SUBMITTALS
THIRD PARTY QUALIFICATIONS
1. Submit qualifications of individual(s) who will perform the work to Design Engineer for approval prior to
commencement of the studies. Study shall be sealed by WI professional engineer.
DRAFT REPORT
1. Submit a draft of the preliminary study to Design Engineer for review prior to equipment shop drawings
submittals. Make all additions or changes as required by the reviewer.
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BWBR, Comm. No. 3. 2013251.00; Henneman Engineering, 13-8091
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C.
D.
FINAL STUDY REPORT
1. Provide studies in conjunction with equipment submittals and after installation of conductors and
equipment to verify equipment ratings required.
2. The results of the power system study shall be summarized in a final report. Six (6) bound copies of the
final report shall be submitted. Provide two (2) copies in PDF format of the study, so that it can be more
easily stored and shared. Also, provide 2 copies (on CD) of the report in MS word, and 2 copies (on CD) of
the one-line diagram in CAD format.
a. The report shall include the following sections:
b. Overview/executive summary/recommendations
c. Short Circuit Study
1) SC-1
Purpose
2) SC-2
Explanation of Data
3) SC-3
Assumptions
4) SC-4
Analysis of Results
5) SC-5
Recommendations
6) SC-6
DAPPER Fault Analysis Input Report
d. Protective Device Coordination Study
1) PDC-1
Purpose
2) PDC-2
Explanation of Data
3) PDC-3
Assumptions
4) PDC-4
Analysis of Results
5) PDC-5
Recommendations (Including NEC 700-27 Requirement)
6) PDC-6
CAPTOR Results
7) PDC-7
Protective device settings table
8) PDC-8
Time-Current Coordination Graphs
e. Arc Flash Study
1) ARC-1
Purpose
2) ARC-2
Explanation of Data
3) ARC-3
Assumptions
4) ARC-4
Analysis of Results
5) ARC-5
Recommendations
6) ARC-6
SKM Arc Flash Evaluation Report
f. Prioritized Recommendations and Conclusions
g. Appendices
1) APP-1
DAPPER One-line Diagrams
2) APP-2
AutoCAD One-line Diagrams
3) APP-3
SKM Protective Device Summaries
4) APP-4
Reference Data
5) APP-5
Sample Work Permit Form
6) APP-6
Copy of Warning Labels, including study date
The above sections shall include the following items in detail:
1. Obtain available fault current from the local utility company.
2. Short circuit studies shall evaluate the available fault current at each bus (each change of impedance),
including all three-phase motors.
3. Coordination study shall provide recommendations for relay settings, breaker settings, and motor
protection settings.
4. Coordination study shall provide recommendations for improving the coordination with proper upgrading
of protective device type or frame size and/or load distribution, as well as ground fault requirements.
5. Arc flash values for two normal cases to define the highest values (low short circuit and high short circuit).
6. Arc flash values for two maintenance cases, which define the arc flash values available at the equipment that
would be available if the instantaneous trip of the upstream circuit breaker is set at a minimum value. This
is recommended if someone has to work on live equipment.
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7.
Arch Flash Hazard Methodology Analysis Results and Recommendations shall include the details of the
incident energy and flash protection boundary calculations, along with Arc Flash boundary distances,
working distances, Incident Energy levels and Personal Protection Equipment levels. Arc Flash labeling
section sowing types of labels to be provided. Section shall contain descriptive information as well as typical
label images.
8. IEEE standard one-line diagram with equipment evaluation and circuit breaker setting forms that clearly
define the system data and are easy to interpret. One-line system diagram that shall be computer
generated and shall clearly identify individual equipment buses, bus numbers used in the short-circuit
analysis, cable and bus connections between the equipment, calculated maximum short-circuit current at
each bus location, device numbers used in the time-current coordination analysis, and other information
pertinent to the computer analysis.
9. Recommendations to reduce the arc flash incident energy in all areas that require class2 and higher PPE.
10. Prioritized report summarizing all recommendations from this study. This shall include observed NEC code
violations and their corrective action.
11. The contractor shall provide a one-line diagram that meets IEEE/ANSI standard 141, mounted on 24” x 36”
(minimum) Styrofoam backboard. This one-line diagram shall be mounted in each electrical room.
1.05
A.
REFERENCE STANDARDS
Institute of Electrical and Electronics Engineers, Inc. (IEEE):
1. IEEE 141 – Recommended Practice for Electric Power Distribution and Coordination of Industrial and
Commercial Power Systems
2. IEEE 242 – Recommended Practice for Protection and Coordination of Industrial and Commercial Power
Systems
3. IEEE 399 – Recommended Practice for Industrial and Commercial Power System Analysis
4. IEEE 241 – Recommended Practice for Electric Power Systems in Commercial Buildings
5. IEEE 1015 – Recommended Practice for Applying Low-Voltage Circuit Breakers Used in Industrial and
Commercial Power Systems.
6. IEEE 1584 -Guide for Performing Arc-Flash Hazard Calculations
B.
American National Standards Institute (ANSI):
1. ANSI C57.12.00 – Standard General Requirements for Liquid-Immersed Distribution, Power, and
Regulating Transformers
2. ANSI C37.13 – Standard for Low Voltage AC Power Circuit Breakers Used in Enclosures
3. ANSI C37.010 – Standard Application Guide for AC High Voltage Circuit Breakers Rated on a
Symmetrical Current Basis
4. ANSI C 37.41 – Standard Design Tests for High Voltage Fuses, Distribution Enclosed Single-Pole Air
Switches, Fuse Disconnecting Switches and Accessories.
C.
The National Fire Protection Association (NFPA)
1. NFPA 70 -National Electrical Code, latest edition
2. NFPA 70E – Standard for Electrical Safety in the Workplace
1.06
A.
B.
C.
D.
QUALITY ASSURANCE
Software algorithms shall comply with requirements of standards and guides specified in this section. Manual
calculations are not acceptable.
Coordination Study Specialist Qualifications: An entity experienced in the application of computer software
used for studies, having performed successful studies of similar magnitude on electrical distribution systems
using similar devices.
1. Professional engineer, licensed in the state where project is located, shall be responsible for the study. All
elements of the study shall be performed under the direct supervision and control of engineer.
Comply with IEEE 242 for short circuit currents and coordination time intervals.
Comply with IEEE 399 for general study procedures.
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BWBR, Comm. No. 3. 2013251.00; Henneman Engineering, 13-8091
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1.07
A.
B.
C.
D.
E.
DATA COLLECTION FOR THE STUDY
The contractor shall provide the required data for preparation of the studies. The engineer performing the
system studies shall furnish the contractor with a listing of the required data immediately after award of the
contract.
The contractor shall expedite collection of the data to assure completion of the studies as required for final
approval of the distribution equipment shop drawings and/or prior to release of the equipment for manufacture.
Source combination may include present and future motors and generators.
Load data utilized may include existing and proposed loads obtained from Contract Documents provided by
Owner, or Contractor.
If applicable, include fault contribution of existing motors in the study. The contractor shall obtain required
existing equipment data, if necessary, to satisfy the study requirements.
PART 2 – PRODUCTS
2.01
NOT USED
PART 3 – EXECUTION
3.01
A.
B.
C.
D.
E.
SHORT CIRCUIT AND COORDINATION STUDY
The short circuit, coordination, and arc flash hazard studies shall be performed using SKM Dapper, Captor and
PowerTool for Windows software packages. In the short circuit study, provide calculation methods and
assumptions, the base per unit quantities selected, one-line diagrams, source impedance data including power
company system characteristics, typical calculations, and recommendations. Calculate short circuit interrupting
and momentary (when applicable) duties for an assumed 3-phase bolted fault at each supply switchgear lineup,
unit substation primary and secondary terminals, low voltage switchgear lineup, switchboard, motor control
center, distribution panelboard, pertinent branch circuit panelboard, and other significant locations throughout
the system. Provide a ground fault current study for the same system areas, including the associated zero
sequence impedance data. Include in tabulations fault impedance, X to R ratios, asymmetry factors, motor
contribution, short circuit KVA, and symmetrical and asymmetrical fault currents.
In the protective device coordination study, provide time-current curves graphically indicating the coordination
proposed for the system, centered on conventional, full-size, log-log forms. Include with each curve sheet a
complete title and one-line diagram with legend identifying the specific portion of the system covered by that
particular curve sheet. Include a detailed description of each protective device identifying its type, function,
manufacturer, and time-current characteristics. Tabulate recommended device tap, time dial, pickup,
instantaneous, and time delay settings.
Include on the time-curve sheets power company relay and fuse characteristics, system medium-voltage
equipment relay and fuse characteristics, low-voltage equipment circuit breaker trip device characteristics,
pertinent transformer characteristics, pertinent transformer characteristics, pertinent motor and generator
characteristics, and characteristics of other system load protective devices. Include at least all devices down to
largest branch circuit and largest feeder circuit breaker in each motor control center, and main breaker in branch
panelboards.
Include all adjustable settings for ground fault protective devices. Include manufacturing tolerance and damage
bands in plotted fuse characteristics. Show transformer full load and 150, 400, or 600 percent currents,
transformer magnetizing inrush, ANSI transformer withstand parameters, and significant symmetrical and
asymmetrical fault currents. Terminate device characteristic curves at a point reflecting the maximum
symmetrical or asymmetrical fault current to which the device is exposed.
Select each primary protective device required for a delta-wye connected transformer so that its characteristic or
operating band is within the transformer characteristics, including a point equal to 58 percent of the ANSI
withstand point to provide secondary line-to-ground fault protection. Where the primary device characteristic is
not within the transformer characteristics, show a transformer damage curve. Separate transformer primary
protective device characteristic curves from associated secondary device characteristics by a 16 percent current
margin to provide proper coordination and protection in the event of secondary line-to-line faults. Separate
medium-voltage relay characteristic curves from curves for other devices by at least a 0.4-second time margin.
8 August 2014
BWBR, Comm. No. 3. 2013251.00; Henneman Engineering, 13-8091
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F.
G.
H.
I.
J.
K.
L.
3.02
A.
B.
3.03
A.
B.
C.
D.
E.
F.
G.
Include complete fault calculations as specified herein for each proposed and ultimate source combination.
Note that source combinations may include present and future supply circuits, large motors, or generators as
noted on drawing one-lines.
Utilize equipment load data for the study obtained by the Contractor from contract documents, including
contract addendums issued prior to bid openings.
Include fault contribution of all motors in the study. Notify the Engineer in writing of circuit protective devices
not property rated for fault conditions.
Provide settings for the chiller motor starters or obtain from the mechanical contractor, include in the study
package, and comment.
When an emergency generator is provided, include phase and ground coordination of the generator protective
devices, to meet NEC 700.27 requirements. Show the generator decrement curve and damage curve along with
the operating characteristic of the protective devices. Obtain the information from the generator manufacturer
and include the generator actual impedance value, time constants and current boost data in the study. Do not
use typical values for the generator.
Evaluate proper operation of the ground relays in 4-wire distributions with more than one main service circuit
breaker, or when generators are provided, and discuss the neutral grounds and ground fault current flows
during a neutral to ground fault.
For motor control circuits, show the MCC full-load current plus symmetrical and asymmetrical of the largest
motor starting current to ensure protective devices will not trip major or group operation.
FIELD SETTINGS AND ADJUSTMENT
The Contractor shall perform field adjustments of the protective devices as required to place the equipment in
final operating condition. The settings shall be in accordance with the approved short circuit study, protective
device coordination study and arc flash hazard study.
Necessary field settings of devices and adjustments and minor modifications to equipment to accomplish
conformance with the approved short circuit and protective device coordination study shall be carried out by
the Contractor at no additional cost to the owner.
ARC FLASH HAZARD STUDY
The arc flash hazard analysis shall be performed according to the IEEE 1584 equations that are presented in
NFPA70E-2009, Annex D. The arc flash hazard analysis shall be performed in conjunction with the shortcircuit analysis (Section 2.03) and the protective device time-current coordination analysis (Section 2.04)
The flash protection boundary and the incident energy shall be calculated at significant locations in the
electrical distribution system (switchboards, switchgear, motor-control centers, panelboards, busway and
splitters) where work could be performed on energized parts.
Circuits 240V or less fed by single transformer rated less than 125 kVA may be omitted from the computer
model and will be assumed to have a hazard risk category 0 per NFPA 70E.
Working distances shall be based on IEEE 1584. The calculated arc flash protection boundary shall be
determined using those working distances.
When appropriate, the short circuit calculations and the clearing times of the phase overcurrent devices will
be retrieved from the short-circuit and coordination study model. Ground overcurrent relays should not be
taken into consideration when determining the clearing time when performing incident energy calculations.
The short-circuit calculations and the corresponding incident energy calculations for multiple system
scenarios must be compared and the greatest incident energy must be uniquely reported for each
equipment location in a single table. Calculations must be performed to represent the maximum and
minimum contributions of fault current magnitude for normal and emergency operating conditions. The
minimum calculation will assume that the utility contribution is at a minimum. Conversely, the maximum
calculation will assume a maximum contribution from the utility. Calculations shall take into consideration
the parallel operation of synchronous generators with the electric utility, where applicable as well as any
stand-by generator applications.
The Arc-Flash Hazard Analysis shall be performed utilizing mutually agreed upon facility operational
conditions, and the final report shall describe, when applicable, how these conditions differ from worst-case
bolted fault conditions.
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BWBR, Comm. No. 3. 2013251.00; Henneman Engineering, 13-8091
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H.
The incident energy calculations must consider the accumulation of energy over time when performing arc
flash calculations on buses with multiple sources. Iterative calculations must take into account the changing
current contributions, as the sources are interrupted or decremented with time. Fault contribution from
motors should be decremented as follows:
1. Fault contribution from induction motors should not be considered beyond 5 cycles.
I.
For each piece of ANSI rated equipment with an enclosed main device, two calculations shall be made. A
calculation shall be made for the main cubicle, sides, or rear; and shall be based on a device located
upstream of the equipment to clear the arcing fault. A second calculation shall be made for the front
cubicles and shall be based on the equipment’s main device to clear the arcing fault. For all other non-ANSI
rated equipment, only one calculation shall be required and it shall be based on a device located upstream
of the equipment to clear the arcing fault.
J. When performing incident energy calculations on the line side of a main breaker (as required per above), the
line side and load side contributions must be included in the fault calculation.
K. Mis-coordination should be checked amongst all devices within the branch containing the immediate
protective device upstream of the calculation location and the calculation should utilize the fastest device to
compute the incident energy for the corresponding location.
L. Arc Flash calculations shall be based on actual overcurrent protective device clearing time. A maximum
clearing time of 2 seconds will be used based on IEEE 1584-2002 section B.1.2. Where it is not physically
possible to move outside of the flash protection boundary in less than 2 seconds during an arc flash event, a
maximum clearing time based on the specific location shall be utilized.
M. Provide the following:
1. Results of the Arc-Flash Hazard Analysis shall be submitted in tabular form, and shall include device or
bus name, bolted fault and arcing fault current levels, flash protection boundary distances, working
distances, personal-protective equipment classes and AFIE (Arc Flash Incident Energy) levels.
2. The Arc-Flash Hazard Analysis shall report incident energy values based on recommended device
settings for equipment within the scope of the study.
3. The Arc-Flash Hazard Analysis may include recommendations to reduce AFIE levels and enhance worker
safety.
3.02.
A.
B.
C.
D.
E.
ARC FLASH LABELS
Engineering Services shall provide a 4.0 in. x 4.0 in. Brady thermal transfer type label of high adhesion
polyester for each work location analyzed.
The labels shall be designed according to the following standards:
1. UL969 – Standard for Marking and Labeling Systems
2. ANSI Z535.4 – Product Safety Signs and Labels
3. NFPA 70 (National Electric Code) – Article 110.16
The label shall include the following information:
1. System Voltage
2. Flash protection boundary
3. Personal Protective Equipment category
4. Arc Flash Incident energy value (cal/cm²)
5. Limited, restricted, and prohibited Approach Boundaries
6. Study report number and issue date
Labels shall be printed by a thermal transfer type printer, with no field markings.
Arc flash labels shall be provided for equipment as identified in the study and the respective equipment
access areas per the following:
1. Floor Standing Equipment - Labels shall be provided on the front of each individual section. Equipment
requiring rear and/or side access shall have labels provided on each individual section access area.
Equipment line-ups containing sections with multiple incident energy and flash protection boundaries
shall be labeled as identified in the Arc Flash Analysis table.
2. Wall Mounted Equipment – Labels shall be provided on the front cover or a nearby adjacent surface,
depending upon equipment configuration.
3. General Use Safety labels shall be installed on equipment in coordination with the Arc Flash labels. The
General Use Safety labels shall warn of general electrical hazards associated with shock, arc flash, and
explosions, and instruct workers to turn off power prior to work.
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BWBR, Comm. No. 3. 2013251.00; Henneman Engineering, 13-8091
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F.
Labels shall be field installed by the Contractor. The technician providing the installation shall have
completed an 8-Hour instructor led Electrical Safety Training Course which includes NFPA 70E material
including the selection of personal protective equipment.
END OF SECTION
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