Short-Circuit Studies

Scope of Study
Determine the short-circuit current available at each component of the electrical system and the ability of the component to withstand and/or interrupt the current. Provide an analysis of all possible operating scenarios which will be or have been influenced by the proposed or completed additions or changes to the subject system.
2. Procedure
The short-circuit study shall be performed in accordance with the recommended practices and procedures set forth in ANSI/IEEE 399 and the step-by-step procedures outlined in the shortcircuit calculation chapters of IEEE 141 and ANSI/IEEE 242.
3. Study Report
Results of the short-circuit study shall be summarized in a final report containing the following items:
1. Basis, description, purpose, and scope of the study.
2. Tabulations of the data used to model the system components and a corresponding one-line diagram.
3. Descriptions of the scenarios evaluated and identification of the scenario used to evaluate equipment short-circuit current ratings.
4. Tabulations of equipment short-circuit current ratings versus available fault duties.
The tabulation shall identify percentage of rated short circuit current and clearly note equipment with insufficient ratings.
5. Conclusions and recommendations.

Coordination Studies

Coordination Studies
* Optional
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ANSI/NETA ATS-2017
1. Scope of Study
1. Determine the extent of overcurrent protective device coordination for the scope:
1. Selective coordination: determine the protective device types, characteristics,
settings, or ampere ratings which provide selective coordination, equipment
protection, and correct interrupting ratings for the full range of available shortcircuit
currents at points of application for each overcurrent protective device.
2. Compromised coordination: determine protective device types, characteristics,
settings, or ampere ratings which permit ranges of non-coordination of overcurrent
protective devices. In this case, overcurrent protective device coordination may be
compromised due to the overcurrent protective devices selected or already
installed or in order to achieve protection of equipment that is selected or already
installed. Objective is to maximize coordination of overcurrent protective devices
to extent possible based on the type of devices. Determine protective device
characteristics, settings, or sizes which provide a balance between equipment
protection and selective device operation that is optimum for the electrical system.
2. Provide an analysis of all possible operating scenarios which will be or have been influenced
by the proposed or completed additions or changes to the subject system.
The coordination study shall be performed in accordance with the recommended practices
and procedures set forth in ANSI/IEEE 399 and ANSI/IEEE 242. Protective device selection
and settings shall comply with requirements of NFPA 70 National Electrical Code.
3. Study Report
Results of the coordination study shall be summarized in a final report containing the
following items:
1. Basis, description, purpose, and scope of the study and a corresponding one-line
diagram.
2. Time-current curves, selective coordination ratios of fuses, or selective coordination
tables of circuit breakers demonstrating the coordination of overcurrent protective
devices to the scope.
3. Tabulations of protective devices identifying circuit location, manufacturer, type,
range of adjustment, IEEE device number, current transformer ratios, recommended
settings or device size, and referenced ti

Arc-Flash Hazard Analysis

Arc-Flash Hazard Analysis
* Optional
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ANSI/NETA ATS-2017
1. Scope of Study
Determine arc-flash incident energy levels and flash-protection boundary distances based on
the results of the short-circuit and coordination studies. Perform the analysis under worstcase
arc-flash conditions for all modes of operation. Provide an analysis of all possible
operating scenarios which will be or have been influenced by the proposed or completed
additions to the subject system.
2. Procedure
Identify all locations and equipment to be included in the arc-flash hazard analysis.
1. Prepare a one-line diagram of the power system.
2. Perform a short-circuit study in accordance with Section 6.1.
3. Perform a coordination study in accordance with Section 6.2.
4. Identify the possible system operating modes including tie-breaker positions, and
parallel generation.
5. Calculate the arcing fault current flowing through each branch for each fault location
in accordance with NFPA 70E, IEEE 1584, OSHA 1910.269, or other applicable
standards.
6. Determine the time required to clear the arcing fault current using the protective
device settings and associated trip curves.
7. Select the working distances based on system voltage and equipment class.
8. Calculate the incident energy at each fault location at the prescribed working distance.
9. Determine the arc-flash hazard PPE category for the calculated incident energy level.
10. Calculate the flash protection boundary at each fault location.
11. Document the assessment in reports and one-line diagrams.
*12. Fabricate and install appropriate labels on the equipment.

Load-Flow Studies

Load-Flow Studies
* Optional
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ANSI/NETA ATS-2017
1. Scope of Study
Determine active and reactive power, voltage, current, and power factor throughout the
electrical system. Provide an analysis of all possible operating scenarios.
2. Procedure
The load-flow study shall be performed in accordance with the recommended practices and
procedures set forth in ANSI/IEEE 399.
3. Study Report
Results of the load-flow study shall be summarized in a final report containing the following
items:
1. Basis, description, purpose, and scope of the study.
2. Tabulations of the data used to model the system components and a corresponding
one-line diagram.
3. Descriptions of the scenarios evaluated and the basis for each.
4. Tabulations of power and current flow versus equipment ratings. The tabulation shall
identify percentage of rated load and the scenario for which the percentage is based.
Overloaded equipment shall be clearly noted.
5. Tabulations of system voltages versus equipment ratings. The tabulation shall identify
percentage of rated voltage and the scenario for which the percentage is based.
Voltage levels outside the ranges recommended by equipment manufacturers,
ANSI/IEEE C84.1, or other appropriate standards shall be clearly noted.
6. Tabulations of system real and reactive power losses with areas of concern clearly
noted.
7. Conclusions and recommendations.

Stability Studies

Stability Studies
* Optional
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ANSI/NETA ATS-2017
1. Scope of Study
Determine the ability of the electrical system’s synchronous machines to remain in step with
one another following a disturbance. Provide an analysis of disturbances for all possible
operating scenarios which will be or have been influenced by the proposed or completed
additions or changes to the subject system.
2. Procedure
The stability study shall be performed in accordance with the recommended practices and
procedures set forth in ANSI/IEEE 399.
3. Study Report
Results of the stability study shall be summarized in a final report containing the following
items:
1. Basis, description, purpose, and scope of the study.
2. Tabulations of the data used to model the system components and a corresponding
one-line diagram.
3. Descriptions of the scenarios evaluated and tabulations or graphs showing the
calculation results.
4. Conclusions and recommendations.