Utility Scale Arc Flash Analysis using
CAPE System Simulator
BIOGRAPHY
• Commonwealth Associates, Inc.
• Project Manager: Ian Hutt, P.E.
• Main office Jackson, MI; remote offices in GA, WA, NM, OH,
and VA.
• Over 200 employees.
• Electrical studies, transmission planning and protection,
substation design, transmission line design, permitting, and
right-of-way acquisition.
What is driving new utility arc flash
requirements?
• IEEE 1584 requires employers to review low voltages, 50-1000
V. NESC 2012 code defers to IEEE 1584, and requires study
specifically for 1000 to 800 kV.
• New NESC 2012 requirements now overrule previous
exception from NESC 2007 for utilities.
• NESC code requires utilities to have compliance by Jan 1,
2009.
• Many utilities are looking for a comprehensive solution that
includes medium and high voltage networks
• References include Table 410-1 and 410-2 in Part 4: Rules for
the Operation of Electric Lines in the NESC code
PROJECT BACKGROUND
• Objective: create a macro in CAPE to allow for easy calculation
of arc flash at specified busses in a utility transmission system
• Project: Study a few select substations, and develop an
engineering report.
• The method used for the select substations could then be
applied to remaining system busses by utility internal staff.
• Arc flash labels and operating procedures could be developed
based on study results.
• Utility wanted to reduce or eliminate arc flash levels to below
Category 2, to reduce or eliminate the need for more bulky
PPE for workers in the field.
THE PROJECT TEAM
Ian Hutt, P.E.
Project Manager / Lead Engineer
Claire Patti, P.E.
Protection Engineer
Chris Nelson, E.I.T.
Protection Engineer
Jeanette Dodge
Engineering Aide
A special thank you to Ashok Gopalakrishnan, Daryl Coleman, and
Paul McGuire at Electrocon International.
PROJECT FLOW CHART
DATA GATHERING
•Receive CAPE Model
•Receive Protection Drawings
MODEL DEVELOPMENT
•Develop model to be fully functional in system simulator
•Validation
ARC FLASH MACRO
•Run Arc Flash Macro
•Compile results
EVALUATION
•Evaluate Results
•Report
•Develop Labels
DATA GATHERING
INFORMATION REQUIRED
FROM UTILITY
• System short circuit model
• Protection drawings (Used to develop and validate
model)
• Relay setting sheets
• Are relay setting sheets and drawings electronic?
• Review with utility protection engineers (to ensure
model accuracy)
MODEL DEVELOPMENT
CAPE ONE LINE
Develop CAPE one-line and compare to existing system diagrams
• Simple vs. detailed bus structures
• Transfer tripping
• Layout
• Formatting
PROTECTION
Evaluate Relays in Model
•
•
•
•
Are settings up to date and accurate?
Are all necessary relays included?
Bus vs. line vs. backup protection
Electromechanical vs. digital relays
What tools are available to bring over relay
settings into CAPE?
CONTACT LOGIC
• System Simulator requires
the use of contact logic to
simulate the tripping outputs
of a relay.
• Contact logic
code/expression rules and
guidelines.
• Use of a standard format for
contact logic expression to
allow for repeatability
• Include use of timers for
certain protection schemes.
VALIDATION OF SYSTEM SIMULATOR
• Run simple test analysis to verify
System Simulator operation.
• Test by placing faults to be picked
up by protection and verify
operation.
• Disable primary protection to
verify timing and operation of
backup protection.
• Can be automated for large scale
checking of network
ARC FLASH MACRO
DEVELOPMENT OF MACRO
• Macro was developed by protection
engineers experienced in arc flash
calculation
• Macro was based on existing arc flash
macro developed by Ashok
Gopalakrishnan at Electrocon
• Macro was developed to provide
output based on total accumulated
incident energy for a specified fault
occurrence
• Macro designed to be used on a large,
utility-scale network to study bus faults
• Macro can be easily adapted to special
cases, based on utility preference
RUNNING ARC FLASH MACRO
• Macro can be run from CAPE System Simulator module.
• First, input macro using CAPE File | Input
• Second, type macro command from command bar
RUNNING ARC FLASH MACRO (continued)
• Once macro is called, a
window will pop up with
choices for the user.
• Can select one bus to
study, or a set of busses.
The set “Allbuses” will
study entire network.
RUNNING ARC FLASH MACRO (continued)
• Choose a fault type;
3PH, SLG, 2PH, LL are
available (only SLG used
for above 15 kV)
• Specify working distance
(18” through 48”
available; macro can be
adjusted to
accommodate special
cases)
RUNNING ARC FLASH MACRO (continued)
• Choose a bus gap
(distance between
busses; macro
recommends gap based
on voltage)
• Specify if faults will be
open or closed box (only
applies for low voltage
faults)
RUNNING ARC FLASH MACRO (continued)
• You can specify the
filename path, or allow
the default
• Select time units in
seconds or cycles
• Macro allows for fault
resistance to reduce
fault current to 85% of
full, per IEEE 1584
recommendations
RUNNING ARC FLASH MACRO (continued)
• Selecting detailed
reporting allows easy
understanding of
results, with a definition
of each value. Selecting
“No” allows for easy
input into a database or
spreadsheet.
RUNNING ARC FLASH MACRO (continued)
• Using the Category filter,
you can get results for
only those areas that
exceed a certain
Category threshold.
• By doing this, you can
study large systems and
only see the areas
where arc flash hazard is
above a certain level.
RUNNING ARC FLASH MACRO (continued)
• Macro runs in System
Simulator; checks
coordination for fault
• Macro runs in a loop
to clear all faults for
each protective
element step (up to
30), recording
accumulated incident
energy level
RUNNING ARC FLASH MACRO (continued)
• Based on the run, the
detailed report
shows the study
results.
• For this case, using
the macro on the
CAPE.GDB database,
bus 150 has a
Category 3 rating.
RUNNING ARC FLASH MACRO (continued)
• The results show the:
– Total fault current
– Total clearing time
– Total incident energy
– Flash protection boundary
• The detailed report shows the
step-by-step results; selecting
“No” to detailed reporting
will show only totals.
Real Data
• Commonwealth Arc Flash macro was run on a real
utility system that has a complete System Simulator
capable model.
• Bus names have been removed for confidentiality.
• Example shows how macro can be applied to a real
model, and used to calculate arc flash hazard for a
system model.
• Model used was a transmission voltage network, and
has simple buses representing substations.
Real Data (continued)
EVALUATION
Real Data Summary
• The results table can be reviewed and results addressed by
severity. Areas with high incident energy levels can be
mitigated to reduce arc flash hazard.
• A full review is required at each location to ensure the results
are accurate and reasonable.
• Below is the summary of results by total:
–
–
–
–
–
–
Category 4+
Category 4
Category 3
Category 2
Category 1
Category 0
5
1
9
3
6
24
Summary of Utility Arc Flash Study Results
25
20
15
10
5
0
1
Over Category 4
Category 4
Category 3
Category 2
Category 1
Category 0
REPORTING AND LABELS
• Results in an Excel spreadsheet or
database program to review data.
• Data can be presented in the form of
an Arc Flash Report deliverable.
• Arc Flash Report can be used as a
guide for developing safe work
practices and procedures.
• Arc Flash Report can be a guide for
selecting appropriate personal
protective equipment (PPE).
• Safety labels created based on the
data to ensure worker safety and
adequate warning for hazards.
WE ARE HAPPY TO PROVIDE MORE
DETAILED INFORMATION REGARDING
METHODS USED IN THIS PROJECT.
Send questions to Ian Hutt
Ian.Hutt@cai-engr.com
QUESTIONS???
QUESTIONS FOR YOU…
• Does your utility have an arc flash study in place?
– For your high voltage network?
– For your distribution voltage network?
– For low voltage devices on your network?
•
•
•
•
Does your CAPE model have System Simulator capability?
Does System Simulator capability have value?
What are the expected costs associated with arc flash study?
What are the expected costs associated with model
development for System Simulator capability?