SECTION 16015
SHORT-CIRCUIT/COORDINATION STUDY/ARC-FLASH ANALYSIS
PART 1 - GENERAL
1.01
REQUIREMENTS
A.
1.02
1.03
The general provisions of the Contract, including General and Supplementary
Conditions and General Requirements, apply to the work specified in this
Section.
SCOPE
A.
The work covered under this Section shall include this Contractor providing an
engineering analysis and coordination study for the [ENGINEER TO EDIT]
[entire electrical distribution system, including existing distribution equipment] –
OR- [new portions of the electrical distribution system as well as all directly
affected existing distribution equipment]. The analysis shall include a shortcircuit analysis with protective device evaluation, a protective device coordination
study, a motor starting study, load flow/voltage drop study, a harmonics analysis
and arc-flash hazard analysis.
B.
The project shall begin at the point of utility service for the facility, through the
main switchboard and continue down through the system, to all downstream 480
volt and 208 volt distribution and branch circuit panelboards, motor control
centers and significant motor locations.
C.
The project shall include generators and any associated emergency power
distribution equipment, including automatic transfer switches and generator
ground fault protection, if equipped.
QUALITY ASSURANCE
A.
The short-circuit /coordination studies and arc-flash hazard analysis shall be
conducted by a Registered Professional Electrical Engineer with a minimum of
five (5) years experience who is skilled in performing and interpreting power
system studies and who is a full-time employee of a firm experienced in the
analysis, evaluation, and coordination of electrical distribution systems, similar to
the system for this project. The firm must have at a minimum four (4) year record
of successful in-service performance.
B.
The studies shall be prepared in accordance with the latest edition of NETA Std.
ATS, NFPA 70B, the “National Electrical Code”, ANSI C2 ”National Electrical
Safety Code”, and ANSI/IEEE Guidelines, as well as manufacturer’s
recommendations.
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C.
1.04
SECTION 16015
The firm conducting the study shall have one million dollars worth of Professional
Liability Insurance in addition to standard general insurance.
SUBMITTALS
A.
Submittals are required in accordance with SECTION 16010 of these
specifications.
B.
The short-circuit and protective device coordination studies shall be submitted to
this project’s Design Engineer of record prior to receiving final approval of the
distribution equipment shop drawings and/or prior to release of equipment
drawings for manufacturing. If formal completion of the studies may cause delay
in equipment manufacturing, approval from the Design Engineer of record may
be obtained for preliminary submittal of sufficient study data to ensure that the
selection of device and characteristics will be satisfactory. Generally, shop
drawing submittals for equipment effected by the coordination study will not be
reviewed until the short-circuit/coordination study has been submitted and
successfully reviewed.
C.
The results of the short-circuit, protective device coordination, and arc-flash
hazard analysis studies shall be summarized in a final report. Submit bound
copies of the final report with tabbed sections, in the quantities required.
Additional copies, where required, shall be provided on CD in PDF format.
D.
The report shall include, but not be limited to, the following sections:
1.
One-line diagram showing protective device ampere ratings and
associated designations, cable size & lengths, transformer kVA and
voltage ratings, motor and generator kVA ratings, switchboard and
panelboard designations.
2.
Descriptions, purpose, basis and scope of the study.
3.
Tabulations of the worst-case calculated short circuit duties as a
percentage of the applied device rating (automatic transfer switches,
circuit breakers, fuses, etc.); the short circuit duties shall be upwardadjusted for X/R ratios that are above the device design ratings.
4.
Protective device time versus current coordination curves with associated
one line diagram identifying the plotted devices, tabulations of ANSI
protective relay functions and adjustable circuit breaker trip unit settings.
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SECTION 16015
5.
Fault study input data, case descriptions, and current calculations
including a definition of terms and guide for interpretation of the computer
printout.
6.
Details of the incident energy and flash protection boundary calculations.
7.
Sample of an arc-flash hazard warning label.
8.
Comments and recommendations for system improvements, where
needed, including extending of feeder or other conductors necessary to
lower the fault-current to an acceptable level.
9.
Executive summary.
PART 2 - PRODUCTS
2.01
2.02
STUDIES
A.
Contractor shall furnish short-circuit and protective device coordination studies
as prepared by the electrical distribution equipment manufacturer or an approved
engineering firm.
B.
Contractor shall furnish an Arc-Flash Hazard Analysis Study performed in
compliance with the latest edition of IEEE Standard 1584 – “IEEE Guide for
Performing Arc-Flash Hazard Calculations” and per NFPA 70E – “Standard for
Electrical Safety in the Workplace”, reference Article 130.3 and Annex D,
prepared by the electrical distribution equipment manufacturer or an approved
engineering firm.
DATA COLLECTION
A.
Contractor shall furnish all field data as required by the power system studies
and arc-flash hazard analysis. The Study Preparer shall furnish the Contractor
with a listing of required data. The Contractor shall expedite collection of the data
to eliminate unnecessary delays and assure completion of the studies as
required for final approval of the distribution equipment shop drawings and/or
prior to the release of the equipment for manufacturing.
B.
Source contribution may include present and future utility supply, motors, and
generators.
C.
Load data utilized may include existing and proposed loads obtained from
Contract Documents provided by Owner or Contractor.
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D.
2.03
Include fault contribution of existing motors in the study, with motors < 50 hp
grouped together. The Contractor shall obtain required existing equipment data,
if necessary, to satisfy the study requirements.
SHORT-CIRCUIT ANALYSIS WITH PROTECTIVE DEVICE EVALUATION
A.
Systematically calculate fault currents based on the available fault current at the
facility service entrance. Study preparer shall obtain the available fault current
from the local utility.
B.
Short-circuit calculations shall be prepared by means of a digital computer
utilizing a commercially available software package. Motor contribution shall be
incorporated in determining fault levels. Results of short-circuit calculations shall
be presented in tabular form and shall include momentary and interrupting fault
values for three-phase and phase-to-ground faults.
C.
Analyze the short-circuit currents by preparing a tabulation comparing the fault
levels to the device interrupting ratings. Indicate areas in which integrated/series
ratings are utilized. The following information shall be included in the tabulation:
1.
2.
3.
4.
5.
6.
2.04
SECTION 16015
Bus identification number.
Location identification.
Voltage
Manufacturer and type of equipment.
Device rating.
Calculated short-circuit current.
PROTECTIVE DEVICE COORDINATION STUDY
A.
Prepare coordination time-current characteristic curves to determine the required
settings/sizes of the protective devices to maximize selectivity. The utility
upstream protective device feeding the facility shall be maintained as the upper
limit for coordination. These settings shall be obtained by the preparer, along
with any other protective device setting requirements. The coordination curves
shall be prepared on log-log paper and illustrate adequate clearing times
between series devices. The curves shall be created through the use of the
study software package, but must reflect actual protective devices to be
installed.
Adequate time-current curves shall be generated to depict
coordination. In addition, protective device characteristics shall be suitably
determined to reflect calculated short-circuit levels at the location.
B.
A narrative analysis shall accompany each coordination curve sheet and
describe the coordination and protection in explicit detail. All curve sheets shall
be multi-color for improved clarity. Areas lacking complete coordination shall be
highlighted and reasons provided for allowing condition to remain or provide
solution to resolve situation. The following information shall be provided on all
curve sheets:
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SHORT-CIRCUIT/COORDINATION STUDY/ARC-FLASH ANALYSIS
1.
2.
3.
4.
5.
6.
7.
8.
2.05
A motor starting study will be prepared in order to analyze the transient effect of
the system’s voltage profile during motor starting. Significant motor starting
voltage profiles must be calculated in order to analyze the effects of the motor
starting on a system basis. The voltage profile as a result of motor starting will
be analyzed based on ANSI/IEEE requirements. The system loading for the
motor starting study will be in accordance with the Load-Flow/Voltage Drop
Study as detailed above. The motor starting study calculations must be
performed using a digital computer utilizing commercially available software.
HARMONICS ANALYSIS
A.
2.08
A load-flow and voltage drop study will be performed to determine the steadystate loading profile of the system. This analysis will be conducted under two
modes of operation. The loading under the first mode of operation will be based
on the instantaneous load values collected during the field effort. The loading
under the second mode of operation will be based on an 80% design criteria of
the load centers. From the results of the load-flow/voltage drop calculations, an
analysis will be prepared, based on the NEC, to indicate areas of overloaded
conductors/loadcenters and areas of excessive voltage drop in the conductors.
The load-flow/voltage drop study calculations must be performed using a digital
computer utilizing commercially available software.
MOTOR STARTING STUDY
A.
2.07
Device identification and associated settings/size.
Voltage at which curves are plotted.
Current multiplier.
ANSI frequent fault damage curve.
Cable insulation damage curves.
Transformer inrush point.
Single-line for the portion of the system.
Motor starting profiles (where applicable).
LOAD-FLOW/VOLTAGE DROP STUDY
A.
2.06
SECTION 16015
The harmonic analysis shall be performed by a computer aided circuit simulation
of the distribution system specific to this project. These calculations shall show
that the total harmonic voltage distortion shall be less than five (5) percent due to
the contribution of all VFD’s supplied.
ARC-FLASH HAZARD ANALYSIS
A.
The Arc-Flash Hazard Analysis shall be performed by a computer aided circuit
simulation of the distribution system specific to this project. These calculations
shall determine the Arc-Flash Incident Energy (AFIE) levels and flash protection
boundary distances. The flash protection boundary and the incident energy shall
be calculated at all significant locations in the electrical distribution system
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SECTION 16015
(switchboards, panelboards, busway, generators, automatic transfer switches,
and motor-control centers) where work could be performed on energized parts.
2.09
B.
The Arc-Flash Hazard Analysis shall be performed in conjunction with the ShortCircuit/Coordination Study.
C.
Results of the analysis shall be submitted in tabular form and shall include as a
minimum the bus name, bolted fault current and arcing fault current level, flash
protection boundary distances, personal protective equipment (PPE) hazard risk
category and the AFIE levels.
D.
The analysis shall be performed under worst-case Arc-Flash conditions, and the
final report shall describe the worst-case conditions when different from worstcase bolted fault conditions.
E.
Arc-Flash Warning Labels:
1.
The Contractor of the Arc-Flash Hazard analysis shall provide Arc-Flash
Warning labels for all electrical equipment that may be opened or
accessed while energized. Labels shall be minimum 3.5 inch x 5 inch
thermal transfer type of high adhesion polyester. Labels shall be
machine printed, with no field markings.
2.
All labels shall be based on recommended overcurrent device settings
and shall be provided after the results of the analysis have been
presented to the Owner and after any system changes, upgrades or
modifications have been incorporated in the system. The labels shall
identify the flash protection boundary, the arc-flash incident energy
(AFIE) level, working distances, required personal protective equipment
(PPE) hazard risk category, nominal voltage, and engineering report
number, revision number and issue date.
SINGLE-LINE DIAGRAM
A.
The final report shall include a multi-color single-line diagram of the electrical
distribution system within the scope of the project. The single-line shall include:
1.
2.
3.
4.
5.
Transformer rating, voltage ratio, impedance, and winding connection.
Feeder cable phase, neutral and ground sizes, length of cable, conductor
material, and conduit size and type.
Switchgear, switchboards, panelboards, MCC’s, fuses, circuit breakers,
ATS’s and switches continuous current ratings.
Protective relays with appropriate device numbers and CT’s and PT’s
with associated ratios.
Detailed legend indicating device type identification and other significant
details.
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SECTION 16015
PART 3 - EXECUTION
3.01
SUMMARY
A.
3.02
3.03
FIELD SETTINGS/ADJUSTMENTS
A.
This Contractor shall engage the equipment manufacturer’s service group or
alternately a qualified independent testing firm to perform field adjustments of
the protective devices as required for placing the equipment in final operating
condition. The settings shall be in accordance with the approved short-circuit
study and protective device evaluation/coordination study.
B.
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 equipment
manufacturer’s service group or qualified independent testing firm
C.
Notify Owner in writing of any required major equipment modifications.
D.
Additions, deletions, upgrades or major modifications to any part of the electrical
distribution system will require re-calculation of the studies and analysis’ for the
portions of the system that has been changed from the original studies. These
re-calculations shall be completed by the same engineer or firm that did the
original studies, at no additional cost to the Owner.
ARC-FLASH WARNING LABELS
A.
3.04
The results of the system studies shall be summarized in a final report. One
“as-built” copy shall be posted in each main electric room.
Apply arc-flash warning labels to equipment. The labels shall be located so as to
be clearly visible to qualified persons before examination, adjustment, servicing,
or maintenance of the equipment.
ARC-FLASH TRAINING
A.
The Contractor of the Arc-Flash Hazard Analysis shall train the Owner’s qualified
electrical personnel of the potential arc-flash hazards associated with working on
energized equipment (minimum of 4 hours). The training shall be certified for
continuing education units (CEUs) by the International Association for Continuing
Education Training (IACET) or equivalent.
END OF SECTION
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