SECTION 260573 - OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY
PART 1 - GENERAL
1.1
SUMMARY
A.
This Section includes computer-based, fault-current and overcurrent protective device
coordination studies. Protective devices shall be set based on results of the protective
device coordination study.
B.
AIC ratings shown on the Drawings and called out in the specifications reflect the
minimum ratings determined. The Contractor shall be responsible for the Coordination
Study.
C.
The Contractor shall have the coordination study done for both the normal and
emergency sides of the distribution system prior to ordering materials and /or
equipment. The Contractor shall submit the study material along with the shop
drawings of the major equipment such as switchboard, panelboards, etc, along
with indications of any increases in equipment sizes or breaker sizes due to the
study outcome. If the Contractor fails to submit the study and obtain approval
prior to ordering materials and/or equipment, then the Contractor shall be held
accountable to make the necessary corrections to those deficiencies identified
by the study at the Contractor’s expense.
1.2
SUBMITTALS
A.
Product Data: For computer software program to be used for studies.
B.
Product Certificates: For coordination-study and fault-current-study computer software
programs, certifying compliance with IEEE 399.
C.
Qualification Data: For coordination-study specialist.
D.
Other Action Submittals: The following submittals shall be made.
1.
2.
3.
4.
Coordination-study input data, including completed computer program input data
sheets.
Study and Equipment Evaluation Reports.
Coordination-Study Report.
See item 1.2C above for additional submittal requirements.
Hancock County, WV
Emergency Management /
9-1-1 Center
OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY
260573 - 1
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dba L.R. Kimball
1.3
QUALITY ASSURANCE
A.
Studies shall use computer programs that are distributed nationally and are in wide
use. Software algorithms shall comply with requirements of standards and guides
specified in this Section. Manual calculations are not acceptable.
B.
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, 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 Professional.
C.
Comply with IEEE 242 for short-circuit currents and coordination time intervals.
D.
Comply with IEEE 399 for general study procedures.
PART 2 - PRODUCTS
2.1
A.
COMPUTER SOFTWARE DEVELOPERS
Available Computer Software Developers: Subject to compliance with requirements,
companies offering computer software programs that may be used in the Work include,
but are not limited to, the following:
1.
2.
3.
4.
5.
6.
2.2
CGI CYME.
EDSA Micro Corporation.
ESA Inc.
Operation Technology, Inc.
SKM Systems Analysis, Inc.
Or Equal as Approved by Professional.
COMPUTER SOFTWARE PROGRAM REQUIREMENTS
A.
Comply with IEEE 399.
B.
Analytical features of fault-current-study computer software program shall include
"mandatory," "very desirable," and "desirable" features as listed in IEEE 399.
C.
Computer software program shall be capable of plotting and diagramming time-currentcharacteristic curves as part of its output. Computer software program shall report
device settings and ratings of all overcurrent protective devices and shall demonstrate
selective coordination by computer-generated, time-current coordination plots.
Hancock County, WV
Emergency Management /
9-1-1 Center
OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY
260573 - 2
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PART 3 - EXECUTION
3.1
A.
3.2
A.
EXAMINATION
Examine Project overcurrent protective device submittals for compliance with electrical
distribution system coordination requirements and other conditions affecting
performance. Devices to be coordinated are all circuit breakers in the main distribution
switchboard exterior and interior and all downstream distribution panelboards and
branch circuit panelboards and the next downstream and upstream devices.
POWER SYSTEM DATA
Gather and tabulate the following input data to support coordination study:
1.
2.
3.
Product Data for overcurrent protective devices specified in other Division 26
Sections and involved in overcurrent protective device coordination studies. Use
equipment designation tags that are consistent with electrical distribution system
diagrams, overcurrent protective device submittals, input and output data, and
recommended device settings.
Impedance of utility service entrance.
Electrical Distribution System Diagram: In hard-copy and electronic-copy
formats, showing the following:
a.
b.
c.
d.
e.
f.
4.
Data sheets to supplement electrical distribution system diagram, crossreferenced with tag numbers on diagram, showing the following:
a.
b.
c.
d.
e.
f.
Hancock County, WV
Emergency Management /
9-1-1 Center
Circuit-breaker and fuse-current ratings and types.
Relays and associated power and current transformer ratings and ratios.
Transformer kilovolt amperes, primary and secondary voltages, connection
type, impedance, and X/R ratios.
Generator kilovolt amperes, size, voltage, and source impedance.
Cables: Indicate conduit material, sizes of conductors, conductor material,
insulation, and length.
Motor horsepower and code letter designation according to NEMA MG 1.
Special load considerations, including starting inrush currents and frequent
starting and stopping.
Transformer characteristics, including primary protective device, magnetic
inrush current, and overload capability.
Motor full-load current, locked rotor current, service factor, starting time,
type of start, and thermal-damage curve.
Generator thermal-damage curve.
Ratings, types, and settings of utility company's overcurrent protective
devices.
Special overcurrent protective device settings or types stipulated by utility
company.
OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY
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g.
h.
i.
j.
3.3
A.
Time-current-characteristic curves of devices indicated to be coordinated.
Manufacturer, frame size, interrupting rating in amperes rms symmetrical,
ampere or current sensor rating, long-time adjustment range, short-time
adjustment range, and instantaneous adjustment range for circuit breakers.
Manufacturer and type, ampere-tap adjustment range, time-delay
adjustment range, instantaneous attachment adjustment range, and current
transformer ratio for overcurrent relays.
Switchgear, switchboards and panelboards ampacity, and interrupting
rating in amperes rms symmetrical.
FAULT-CURRENT STUDY
Calculate the maximum available short-circuit current in amperes rms symmetrical at
circuit-breaker positions of the electrical power distribution system. The calculation
shall be for a current immediately after initiation and for a three-phase bolted short
circuit at each of the following:
1.
2.
3.
Switchboard bus.
Distribution panelboard.
Branch circuit panelboard.
B.
Study electrical distribution system from normal and alternate power sources
throughout electrical distribution system for Project. Include studies of systemswitching configurations and alternate operations that could result in maximum fault
conditions.
C.
Calculate momentary and interrupting duties on the basis of maximum available fault
current.
D.
Calculations to verify interrupting ratings of overcurrent protective devices shall comply
with IEEE 242.
E.
1.
Transformers:
2.
a.
ANSI C57.12.10.
b.
ANSI C57.12.22.
c.
ANSI C57.12.40.
d.
IEEE C57.12.00.
e.
IEEE C57.96.
Low-Voltage Circuit Breakers: IEEE 1015 and IEEE C37.20.1.
Study Report:
1.
Show calculated X/R ratios and equipment interrupting rating (1/2-cycle) fault
currents on electrical distribution system diagram.
Hancock County, WV
Emergency Management /
9-1-1 Center
OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY
260573 - 4
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F.
Equipment Evaluation Report:
1.
2.
3.
3.4
For 600-V overcurrent protective devices, ensure that interrupting ratings are
equal to or higher than calculated 1/2-cycle symmetrical fault current.
For devices and equipment rated for asymmetrical fault current, apply
multiplication factors listed in the standards to 1/2-cycle symmetrical fault current.
Verify adequacy of phase conductors at maximum three-phase bolted fault
currents; verify adequacy of equipment grounding conductors and grounding
electrode conductors at maximum ground-fault currents. Ensure that short-circuit
withstand ratings are equal to or higher than calculated 1/2-cycle symmetrical
fault current.
COORDINATION STUDY
A.
Perform coordination study using approved computer software program. Study shall be
in accordance with the latest applicable IEEE and ANSI standards.
B.
The Coordination Study shall contain time-current curves, centered on conventional
full-size log-log forms, graphically indicating the coordination proposed for the system.
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.
C.
Include on the curve sheets power company relay and fuse characteristics, mediumvoltage equipment protective relay and fuse characteristics, low-voltage equipment
circuit breaker trip device characteristics, pertinent transformer characteristics,
pertinent motor and generator characteristics, and characteristics of other system load
protective devices.
D.
Include all adjustable settings for ground fault protective devices (If Applicable). Include
manufacturing tolerance and damage bands in plotted fuse characteristics. Show
transformer full load currents, transformer magnetizing inrush, ANSI transformer
withstand parameters, and significant symmetrical fault currents. Terminate device
characteristic curves at a point reflecting the maximum symmetrical fault current to
which the device is exposed.
E.
At the stand by generator include phase and ground coordination of the generator
protective devices. Show the generator decrement curve and damage curve along with
the operating characteristic of the protective devices.
Hancock County, WV
Emergency Management /
9-1-1 Center
OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY
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dba L.R. Kimball
3.5
A.
COORDINATION STUDY REPORT
As a minimum the report shall include the following sections:
1.
2.
3.
4.
5.
3.6
A.
3.7
A.
Executive Summary including system descriptions, purpose, basis, scope of the
study, results and recommendations.
Tabulations of circuit breaker, fuse, and other protective device ratings versus
calculated short-circuit duties, including narrative description.
Protective device time versus current coordination curves, tabulations of relay
and circuit breaker trip settings, and fuse selection, including narrative
description.
Study Printouts.
Diagrams.
DESIGN PROFESSIONAL APPROVAL
Approved copies of the report shall be submitted to the Engineer as specified above.
FIELD SETTINGS
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 protective device Coordination Study.
Necessary field settings of devices and adjustments and minor modifications to
equipment to accomplish conformance with the protective device Coordination Study
and system performance shall be carried out by the Contractor at no additional cost.
END OF SECTION 260573
Hancock County, WV
Emergency Management /
9-1-1 Center
OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY
260573 - 6
12-2200-0128
CDI Infrastructure, LLC
dba L.R. Kimball