36C25618R0260-00001003.pdf

Electrical System Assessment 1

1.0 Executive Summary

SSOE Group has been commissioned by the Department of Veterans Affairs to conduct an Electrical System Assessment of the VA Medical Center in Shreveport, Louisiana. The scope of this study includes short circuit analysis, protective device coordination, voltage drop calculations, arc flash hazard analysis and equipment condition assessment. The study begins at the incoming utility service (for the normal system) and at each emergency generator (for the emergency system), continuing through each branch to the distribution panels, motor control centers and branch circuit panels in each building.

In order to conduct the system assessment, SSOE personnel conducted two onsite surveys to obtain the necessary data and information on the existing electrical distribution system for the Shreveport VAMC. The first survey was conducted between Monday, February 9, 2014 and Friday, February 15, 2014; and again between Monday April 13, 2014 and Friday, April 18, 2014. These visits completed the bulk of the field investigation required for this project. Information was also obtained from facility record drawings. Wherever possible the information shown on the record drawings was confirmed by on-site inspection.

The field survey was performed in order to obtain actual equipment data required for the modeling of the site electrical distribution system, as well as to conduct a system assessment. As expected, some of the equipment data was not available and a certain amount of engineering assumptions were made. A list of the major assumptions can be found in each section where applicable. The electrical system information was used to build a power system model using “SKM - Power Tools for Windows” in a one line diagram format. The data entered included nameplate data and/or specifications for transformers, motors, generators, protective devices, panelboards, distribution panels, unit substations and system wiring. Using the “Dapper“ module in the SKM software, an electrical short circuit study was completed to establish the available fault current at each point application or bus. Other modules were used to conduct a system analysis of the arc flash hazard, protective device coordination and an evaluation of suitability of electrical equipment.

The Shreveport - VAMC is electrically served at 12.47kV from the Southwest Electric Company. There is one dual feed utility drop at the North West end of the campus. The utility service is routed underground to a 15kV pad mounted primary switch enclosure located between the Maintenance Building and the Emergency Generator building. Service is then routed underground throughout the site to the various buildings. The Dental Clinic, Building 57, located at the South East corner of the site is fed with a separate service.

An electronic copy of the complete data reports for the Base Scenario (existing conditions) as reported by SKM Power*Tools is included on the accompanying CD.

As a result of this study the following things should be noted:

1.1 Short Circuit

The following items summarize the results of the Short Circuit study:

The vast majority of the system equipment is properly rated to withstand the available short circuit fault currents.

The protective breakers that are overdutied are highlighted in Appendix SC B. Under fault conditions, these circuits could fail or cause equipment damage and could be a safety hazard for personnel. See Appendix SC B – 3 Phase Short Circuit Report for recommended breaker replacement.

1.2 Arc Flash Hazard

The following items summarize the results of the Arc Flash study:

Most of the electrical system is at a PPE Category 2 or less. Many devices are PPE Category 0.

There are a number of devices that are at PPE Category DANGEROUS. There is currently no recognized

Electrical System Assessment 2 safety equipment that can provide protection for this level of blast hazard caused by an arc flash. Any device with this rating should not be worked on or maintained under any circumstance when energized.

Regardless of a unit’s PPE Category; whenever possible, equipment should be de-energized before working on or around electrical parts. This should be the highest priority. Please note that proper PPE is required to confirm that the electrical parts are de-energized.

It may be possible to mitigate the arc flash hazard in areas but many would require more in depth analysis and significant equipment changes.

1.3 Protective Device Coordination

The protective device coordination study examined the ratings and settings of the existing overcurrent protective devices and identified those devices that are currently not properly coordinated. In a properly coordinated system, the device closest to the fault will interrupt the circuit, thus minimizing the potential disruption to the electrical system.

In order to determine the systems degree of coordination, we have developed and plotted Time Current Characteristics (TCC) to show the existing relationships between the medium and low voltage fuses, breakers and equipment damage curves. Where the TCCs showed miscoordination, we have included updated curves immediately following the existing curves showing the revised settings

The majority of the protective devices have the proper selective coordination.

There are 11 protective breakers that are not properly coordinated or too close to the upstream device tripping curve. Under fault conditions, these circuits could fail or cause equipment damage and could be a safety hazard for personnel.

The list of protective device revisions and all existing and updated coordination curves are included in the section appendix.

1.4 Emergency Power System

The overall emergency systems for the main hospital, boiler plant, chiller plant and Building 6 are in excellent condition.

1.5 Ground Resistance

As described in VHA Directive 2006-056, each facility should test the ground system every 36 months. A copy of this report would be available for any system analysis. The VAMC was unable to provide a copy of a current ground analysis.

The ground system is in overall poor condition. Testing has not been done, and, therefore test results were not available.

The overall ground system for Building 1 is over 30 years old and is in poor condition. In addition to the age of the ground system, modifications and additions have been made that, based on our observation, have further eroded the system effectiveness.

1.6 Voltage Drop

A load flow analysis has been performed in order to determine voltage drop along each feeder. In order to accurately model the system load flow, load data was obtained from SWEPCO, the utility serving the Shreveport VAMC. This information has been used to establish loading on the medium voltage system. As specified in the project Scope of Work, Part IV, g. Voltage Drop Calculations; low voltage loads at the facility are defined as 80 percent of the nameplate rating. This level of loading is most likely higher than what would be seen if actual meter readings were used but represent a worst case condition. Actual, metered load data would provide a voltage drop

Electrical System Assessment 3 analysis closer to the actual field conditions and would provide more functional recommendations.

There are Twenty-four (24) feeders that should be monitored due to a calculated, excessive voltage drop.

These are tabulated in the Voltage Drop section.

1.7 Analysis and Recommendations

With the exception of Building 1, the overall condition is in fair to good condition.

During our investigation of Building 1 a consistent set of issues were encountered. These are described in the

Analysis and Recommendation section and are further documented in Appendix AR B – Photographs.

The electrical equipment grading system was as defined in the project Scope of Work, Part IV, i., Analysis and Recommendations.

Recommendations for corrective action, along with a Budget Cost Opinion are included in the assessment table. The budget costs represent programming level costs and are based on several assumptions which are outlined in the body of this report. These budget costs do not include construction contingencies, construction phasing, special or unique site/project conditions, off-peak construction, etc. In addition, some of the recommended upgrade/ correction may require power outages to affected buildings or areas. The extent of any outages is beyond the scope of this report and will vary from building to building. Avoiding any outage may require creative phasing plans and this will also affect the overall costs.

An electronic copy of the complete input data report for the Base Scenario (existing conditions) as reported by SKM Power*Tools is included on the accompanying CD.

Finally, we would be remiss if we did not thank the following individuals who went above and beyond to ensure the success of this project:

Mark T Shore, P.E. Chief of Engineering, Telephone 318-990-5210 E-mail mark.shore@va.gov

Matthew DeGeorge Assistant Chief Engineer Telephone 318-990-5273 E-mail matthew.degeorge@va.gov

Justin Kraker MTO Supervisor Telephone 318-990-5430 E-mail justin.kraker2@va.gov

Mark Hays Operations Supervisor Telephone 318-990-5210 E-mail mark.hays@va.gov

Steve McCleary Maintenance Supervisor Telephone 318-990-5240 E-mail steve.mccleary@va.gov

Sandy Bellows Maintenance Telephone 318-990-5040 E-mail sandy.bellows@va.gov

Jack Spring, Jr. President, Jack Spring Electric Telephone 318-865-6225 E-mail jsspring@jackspringelectric.com

Mike Smith, Jack Spring Electric Kenneth Allume, Chad Primos

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2.0 Introduction

SSOE Group was contracted by the Department of Veterans Affairs to analyze the electrical power system at their Overton Brooks – VAMC facility in Shreveport, Louisiana. The analysis is to include the following studies:

Short circuit analysis

Protection device coordination analysis

Arc flash study

Load flow/voltage drop analysis

Emergency power system analysis

Ground system analysis

Overall system condition

The short circuit and arc flash one line drawings reflect the current system configuration from field documentation.

All systems are recorded based on our site visits from February 9, 2014 through February 15, 2014 and April 13, 2014 through April 18, 2014.

2.1 System Tools

In order to support short circuit, protective device coordination, arc flash, and voltage drop, SSOE has utilized SKM power*tools for windows, version 7.1.

2.2 System Description

The Shreveport - VAMC facility consists of the main hospital building, out-patient clinics and ancillary support buildings. The facility is fed by SWEPWCO with 3 different service points. The service entrance point has been identified by the utility to be the termination on the line side of the 12.47kV switchgear.

FDR Location Transformer Size Service Voltage 52-2 Building 1 – Service 1 USS A – 1000 kVA

USS B – 1000 kVA USS C – 750 kVA

208/120V 208/120V 480/277V

52-3 Building 1 – Service 2 USS A – 1000 kVA USS B – 1000 kVA USS D – 500 kVA

208/120V 208/120V 208/120V

52-5 Spare 52-6 Building 1 – South Wing

Building 4 Building 6 Building 55

Bldg 1 – 1500 kVA Bldg 4 – 300 kVA Bldg 6 – 300 kVA Bldg 55 – 300 kVA

480/277V 208/120V 208/120V 480/277V

52-7 Building 2 – Boiler Plant Building 2 – Chiller Plant

Boiler Plant – 225 kVA Chiller Plant – 1500 kVA

208/120V 480/277V

Based on data provided by the Overton Brooks VA maintenance staff the maximum demand for the 12 month period 5/13-4/14 was 3,118kW at 90.7% power factor, in June, 2013. This amounts to approximately 159.4Amps at 12.47kV. Based on this information and assuming this demand is evenly distributed over both utility services, the peak demand on one service is 79.7A is approximately 25% of 80% (320A) of the main fuse rating of 400A.

This indicates that the main services have adequate spare capacity for any future growth.

The third service is for the 2012 Dental Clinic building on the South East side of the campus.

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The main hospital has 2 generators of 750KVA each.

The boiler and chiller plants each have separate emergency generators. The boiler plant generator is 750kVA and the chiller plant generator is 1250kVA. Building 6 has a 100kVA generator.

2.3 Short Circuit

The short circuit calculations determine available short circuit levels throughout the electrical distribution system under various operation conditions. Using equipment data and available fault current data from El Paso Electric Company, we conducted short circuit calculations using “SKM – Power Tools for Windows” to determine available short circuit current levels throughout the electrical system. The results of these calculations were used to determine the suitability of the electrical system to handle potential faults. These calculations further aid in coordinating these protective devices. The rating for most medium and low voltage equipment appears adequate for the available fault current.

The majority of the electrical system is properly rated to withstand the calculated short circuit fault currents.

The breakers found to be overdutied, could under fault conditions, fail to open or cause equipment damage and could be a safety hazard for personnel.

The list of equipment overdutied has been tabulated and is included in the Short Circuit section. The list of equipment overdutied and the Short Circuit One-line Diagrams are included in the section appendices.

2.4 Arc Flash Hazard

As defined by IEEE Standard 1584, “Guide for Performing Arc-Flash Hazard Calculations”, arc flash hazard is a dangerous condition associated by the release of energy caused by an electrical arc. According to this same standard; a flash hazard analysis is a method to determine the risk of personal injury as a result of exposure to incident energy from an electrical arc flash. The arc flash hazard analysis conducted for the El Paso VA Clinic was used to establish safe flash protection boundaries and suitable personnel protection equipment (PPE).

The arc flash calculations determined the level of incident energy (expressed as units of calories per centimeter squared, “cal/cm^2”) that personnel could be exposed to at a given distance.(typically 18”) from the fault. In addition the calculations define the arc flash boundary (AFB) as the distance where a person could receive a second degree burn. It must be understood that a posted arc flash boundary does not define a safe or injury free distance but rather a distance that a person could receive up to second degree burns in the event of an arc flash incident.

Using information collected during our field investigation, provided in record documents and data received from VAMC personnel, an arc-flash hazard analysis was completed using the arc flash module of SKM – Power Tools for Windows. Arc flash warning labels that include the incident energy, arc flash boundaries, bolted fault and recommended PPE protection will be provided for each piece of electrical equipment.

The following summarizes the results of the Arc Flash analysis:

Most of the electrical system is at a PPE Category 2 or less. Many components are PPE Category 0.

There are a number of devices at PPE Category DANGEROUS. There is currently no safety equipment that can provide protection for this level of arc flash. Any device with this rating should not be worked on or maintained under any circumstance when energized.

Whenever possible, de-energize equipment before working on or around electrical parts. Working on energized equipment is a choice of last resort. It should be noted that PPE is required to confirm that the electrical parts are de-energized.

Arc flash mitigation will require a more in depth analysis of the electrical system to ensure protective device coordination is not compromised. This may require additional, significant equipment changes.

The complete list of equipment arc flash values and the Arc Flash One-line Diagrams are included in the section appendices.

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2.5 Protective Device Coordination

The protective device coordination study analyzed the ratings and settings of the existing overcurrent protective devices and identified those devices that are currently not selectively coordinated. Using the “Dapper” module of SKM – Power Tools for Windows, the existing ratings and settings have been examined for coordination between upstream and downstream devices.

In a properly coordinated system, the device closest to a fault should interrupt the circuit, thus minimizing the potential disruption to the electrical system. For this reason, a selectively coordination provides for a more reliable system.

For this study, coordination will be examined from 0.1 seconds and above. Both NFPA-70E-2012 “Electrical Safety in the Work Place” and NFPA-101-2012 “Health Care Facility Code”, consider overcurrent protection devices serving essential electrical systems shall be considered coordinated above 0.1 seconds.

There are cases where devices could not be made to fully coordinate without significant device or equipment changes.

Most thermal-magnetic breakers have limited coordination capabilities, replacing them with electronic trip breakers with narrower, adjustable bands will be required to achieve coordination.

There are a number of protective devices that will not coordinate regardless of breaker settings or replacement. There are a number of reasons why this condition occurs:

- The downstream device is relatively close in ampacity to the upstream device.

- Both the downstream and upstream devices have the same ampacity rating. This condition can be further compounded if the devices are of different breaker styles or manufacturer.

- The downstream device is a larger ampacity than the upstream device.

- One or both devices are non-adjustable.

Breakers with both phase and ground fault functions are shown on separate curves for clarity.

The list of protective device revisions and all existing and recommended coordination curves are included in the appendices following the Protective Device Coordination section.

2.6 Emergency Power System

To date we have not received any generator load testing data, however with the current replacement project underway, the suitability of the existing generators is not an issue. We recommend that the local staff initiate a regular schedule of generator load testing to ensure current and future emergency loads are adequately served.

2.7 Ground Resistance

As described in VHA Directive 2006-056, each facility should test the ground system every 36 months. A copy of this report would be available for any system analysis. The VAMC was unable to provide a copy of a current ground analysis but did produce a testing result from 9/19/2001.

Commissioning a ground resistance analysis, including locating and documenting the facility ground system should be a high priority.

2.8 Voltage Drop

A load flow analysis has been performed in order to determine voltage drop along each feeder. In order to accurately model the system load flow, load data was obtained from EPEC, the utility serving the El Paso VAMC.

This information has been used to establish loading on the medium voltage system. As specified in the project Scope of Work, Part IV, g. Voltage Drop Calculations; low voltage loads at the facility are defined as 80 percent of the nameplate capacity or current limiting device. This level of loading is most likely higher than what would be seen if actual meter readings were used but represent a worst case condition. Actual, load survey data would

Electrical System Assessment 7 provide a voltage drop analysis closer to the actual field conditions and would provide more functional recommendations.

Based on our field observations and review of available record documents there are a number of feeders that are undersized based on the overcurrent protective device. These feeders are identified in the Voltage Drop section.

This arrangement produces long feeder runs to any panel or equipment on the north side of the clinic.

2.9 Analysis and Recommendations

The electrical equipment assessment has been carried out in order to identify equipment in poor, inoperable or unsafe condition. For the purpose of this assessment we used the grading system as defined in the project Scope of Work, Part IV, i., Analysis and Recommendations using the following grading methodology:

Grade A = Like new condition. Majority of useful life span remains. “Excellent”.

Grade B = Good condition. Over half of useful life span remains. “Good”.

Grade C = Average condition. Less than half of useful life span remains. “Fair”.

Grade D = Poor condition. Past useful life span but still functioning. “Poor”.

Grade F = Critical condition. Needs immediate attention. “Failing” or “Critical”.

Where degrading conditions were observed (i.e. visible water damage, rust, mechanical damage, etc.) grading was performed using engineering judgment. Where equipment did not exhibit any degrading conditions, grading was based on the VHA Program Guide PG-18-3 “Service Life and Replacement Cycles” of 40 years for electrical systems.

Issues related to National Electrical Code, NFPA-70, 2014 compliance are incorporated into the equipment assessment table.

Recommendations for corrective action, along with a Budget Cost Opinion are included in the assessment table.

The budget costs represent programming level costs and are based on several assumptions which are outlined in the body of this report. These budget costs construction contingencies, phasing related mark-ups, special or unique site/project conditions, off-peak construction, etc. In addition, some of the recommended upgrade/ correction may require power outages to affected buildings or areas. The extent of any outages is beyond the scope of this report and will vary from building to building. Avoiding any outage may require creative phasing plans and this will also affect the overall costs.

The system assessment, by building, along with recommendations and costs can be found in the Analysis and Recommendations section.

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Appendix A – Site Investigation Kick-Off Meeting Minutes

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Appendix B – Comments and Responses

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VACO Comments – Shreveport 60% Submittal

1) It will make the report more user-friendly to include sections of Protective Device Evaluation, Protective

Device Analysis & Recommendations & Equipment Evaluations. See attached examples (Tables 3.1, 3.2, 3.3) Response: The 90% submittal includes a Protective Device Evaluation, Device Analysis & Recommendations and a facility Equipment Evaluation.

2) It will make the report more user-friendly by providing comments on each TCC, see attached example of

TCC analysis and recommendations Response: TCC comments are included in Appendix PDC A of the Protective Device Coordination section.

Each existing TCC is commented on.

3) To make the report more user-friendly if we can show existing & recommended settings in table format under for medium/low voltages, see attached example (Tables 4.1 & 4.2).

Response: A summary of setting changes is included in Appendix PDC C of the Protective Device Coordination section. Only those breakers that have recommended settings changes are included in the tabulation with the recommended revisions highlighted.

4) SSOE may have the experience in developing technical documents for many different clients by using their format. Over the years, we have developed our own format that our reviews are accustomed to and we ask our consultants to follow the format shown in our sample study so the time to the review can be shorten and the review process can be more effective.

Response: The sample report format has been noted and incorporated into the 90% submittal.

5) It appears the executive summary is a boilerplate version, almost the same as Tuscaloosa, Iron Mountain &

El Paso. Provide a site specific overview of normal medium/low voltage systems including emergency/standby systems.

Response: At the time of the 60% submittal we were still analyzing the data we had gathered from our first site visit. The Executive Summary included in this submittal is site specific for the Shreveport VAMC facility.

6) Coordination Curve TCC-BLDG6, it appears that downstream device PD-BLDG 12 & 14 and upstream device MCB-6 NQSB overlap between 0.10 to 1 second. What should we recommend to the facility -replace breaker, new setting, or other? If improvement can be made, provide recommended curve and description. See attached sample.

Response: The adjustments recommended in the Protective Device Coordination section and the associated TCC’s (Appendix PDC B) will provide proper coordination.

7) Many Time Coordination Curve (TCC’s) appear to be either overlapping, touching or crossing over, but

“recommended conditions” are not provided for review. Provide description for existing and recommended curves. Put both curves side by side on the report. See attached sample.

Response: Recommended improvements and associated revised Time Coordination Curves are included in the Protective Device Coordination section.

8) Table of Content (TOC), even for 60% or 90% deliverables, show a full TOC as intent for 100%. And each section of the report shall be divided with tab.

Response: Comment is noted and will be followed on all future submittals and power system analysis projects.

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VACO Comments – Shreveport 60% Submittal

9) We have shown over 50 failed devices on the report, please provide explanation and recommendation for corrective action.

Response: Recommended improvements and associated revised Time Coordination Curves are included in the Protective Device Coordination section.

10) We look forward to the next report which will include a more comprehensive analysis. Lots of work still waiting to be done before next submittal.

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VACO Comments – Shreveport 90% Submittal

1) Table of Content (TOC), it is kind of odd looking to have Appendix in between each section. Is there a good reason why we don’t number the Section and subsection the way the TOC shown in our previous sample? We prefer to see something like:

1. Introduction

1.1 Site Investigation

1.2 Comments and Response

Response: Having the section appendices as a part of the section allows each individual section to be a standalone component and places all of the information regarding that topic or section in a single location.

Subsection numbers and listing in the TOC have been added.

2) Improved TCC’s, analysts and recommendations are included for review. Thank you.

3) This report included the overview of the medium voltage underground, normal and emergency systems.

Thank you.

Response: Executive summary and system description has been revised and expanded.

4) Label should have building number, recommended PPE and Fault Current.

Response: Equipment labels with the requested information will be used.

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5) We like the way SSOE organized the Equipment Condition Assessment Table, it clearly states where, what and how much to correct each item. The provided information is going to benefit the staff or consultant who is going to input the deficiencies to CAI database Response: Noted. Thank you.

6) Before 100% submittal, coordinate a conference call with medical center, VHA and CFM. The intent of this meeting is to offer an opportunity to end users (medical center, VHA, etc) to address any of their concerns regarding to the report.

Response: Baseline review was held, via conference call, on X/X/2014. Meeting minutes are included in Appendix D – Baseline Review, in the Executive Summary section of the final report.

7) As a reminder that for the 100% submittal, VHA, CAM and CFM will get an abridged hard copy (with all files including SKM backup copy on CD & pdf formatted report). The VAMC still gets the full set of hard copy & CD at 100%.

Response: Noted. Thank you.

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3.0 Short Circuit

3.1 Purpose

In order to adequately supply the required power on demand to a facility's power distribution system, electric utilities must maintain ample capacity in reserve. This reserve capacity, in combination with the motor loads, can also supply excessive current to the distribution system during a fault condition. The purpose of the Short Circuit Study is to examine various components of the distribution system in order to calculate and analyze the available current levels which can occur throughout the system during a fault condition. The available fault currents can be hazardous to both equipment and personnel if not considered and handled in a proper manner. This study provides necessary information for sizing and setting overcurrent protection devices and selecting equipment bracing levels by determining the maximum available 3-phase symmetrical fault currents that will occur at points in the distribution system. Proper selection and setting of overcurrent devices and sizing of equipment bracing are essential to survive a fault with minimal effect and damage to the distribution system.

3.2 Computer Program Description

Mathematical calculations for this study were performed by a computer program. It was necessary to review the data which was used in the program so that proper interpretation can be applied to the results or output of the program. The program utilized for this study was SKM Power Tools for Windows Software from SKM Systems Analysis, Inc.

3.3 System Model

Using documents received from the Shreveport staff, utility information and equipment data collected during our field surveys, the electrical system at the Shreveport - VAMC was modeled using SKM Power*Tools software.

The individual models follow the breakdown of the existing distribution system:

The Primary model includes the incoming service from the local utility to the secondary bus of the utility service transformers. Building 57 – Dental Clinic is served separately from SWECO off of their Stoner Av.

distribution line. This service is included in the Building 57 model.

Building 1 Main Building is broken down into 7 separate models; 1 for each of the unit substations (USS A, B, C and D), the South Wing expansion, Emergency generator #1 and #2. The emergency system transfer switches are modeled to the normal bus of each ATS. The emergency loads are included on the appropriate emergency system model.

Building 42-CT/PET is fed from Building 1 – Unit Substation C.

Building 2-Boiler Plant includes the panels and equipment associated with the central boiler plant building.

This includes a separate emergency generator.

Building 2-Chiller Plant includes the panels and equipment associated with the central chiller plant, including the cooler towers and a separate emergency generator.

Building 4-Engineering includes, in addition to Building 4, services to Building 16 and Building 33.

Building 6-Administration includes, in addition to Building 6, service to Buildings 12 and 14. Building 6 includes a separate generator which service only Building 6.

Building 55-Specialty Care includes the panels and equipment associated with Building 55.

Building 57-Dental Clinic includes the panels and equipment associated with the dental clinic. As mentioned above, the dental clinic is fed separately from the rest of the Shreveport facility. The dental clinic utility service is included in the Building 57 model.

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3.4 Computer Calculations

For the purpose of calculating short circuit current levels, the electrical distribution system is reduced to a network of positive (+), negative (-), and zero (0) sequence impedance elements (resistance (R) and reactance (X)) and power sources. Impedance elements consist of cables, busways, transformers, transmission lines, reactors, and motor and generator windings. Power sources are rotating motors, generators, and utility fault contributions.

Each node of this impedance network is assigned a "bus" name corresponding to the equipment names as shown on the system one-line drawings. Some arbitrary bus numbers were used for the equipment with no associated name. Using these bus names and impedance elements, the computer program associated all elements and power sources, thereby creating a model of the distribution system as it physically exists.

The Short Circuit Program must be provided with physical information about each device in the distribution system (i.e., transformer kVA and percent impedance; cable length, size and utilization voltage; etc.). This information is shown on the one line diagrams in Appendix SC C – Short Circuit One-Line Diagrams. The input data is reduced to per unit values of positive (+), negative (-) and zero (0) sequence resistance and reactance, on a common MVA base, by using typical (or nameplate) impedance values and standard calculations. The input data can be displayed on the computer screen or printed out for ease of checking.

The fault components to be calculated by the Short Circuit Program are selected by the user. For this study, the following components have been calculated: The 3-phase and single-line-to-ground steady state symmetrical components.

The variable impedance of the arc during an arcing fault can reduce the fault current magnitudes to those shown in the Arc Flash Data Table in Section 3 of this report. Refer to IEEE Red Book, IEEE/ANSI Std. 141-1993, pg.

113-114 for a discussion on arcing faults.

3.5 Assumptions

During the course of calculating short circuit currents, various assumptions must be made when exact information is not available or when the use of exact information would not contribute to greater accuracy of the results. The SKM program utilizes a number of default values for calculations. These values are utilized unless specific data has been identified to vary from these default values. Assumptions made by SSOE Group in the input data to the program are as follows:

All equipment, devices, conduit, wiring, etc. were entered into the study as shown on the drawings or in the previous model, from information supplied by others, and/or as designed

All motors 25 HP and above are fed from a Variable Frequency Drives (VFD) with the exception of the fire jockey pump.

The fault contribution of motors 25 HP and below was not included. IEEE 1584 points out that motors less than 50 HP do not need to be included in calculations due to the limited short circuit contribution.

Utility transformer data, such as percent impedance and X/R values were acquired from data provided by Southwest Electrical Power Company. SSOE recommends that the VAMC verify the utility values whenever system changes are made, to guarantee proper equipment ratings.

Conductor impedances are based on IEEE Standard 141-1993 (per SKM default libraries).

Cable data for #3 copper cables was not included in the SKM libraries. Therefore #2 copper cables were utilized. This results in lower system impedance and will therefore show slightly higher available fault currents.

3.6 Conclusions

With the available short circuit fault current, each breaker and fuse can be assessed for their rated capacity to

Electrical System Assessment 27 handle the available calculated fault. Thus, it can be determined if the available short circuit current at each device exceeds the device ratings (overdutied). Based upon the available information on equipment withstand ratings, protective device interrupting current levels and the results of our study, the Shreveport distribution system is properly rated for the available fault. The exceptions are shown in Appendix SC – B – 3 Phase Short Circuit Report, Protective Device Appraisal.

SWEPCO provided the minimum available short circuit current. This is the available fault current of the system.

This must be used to evaluate the duty capacity of your existing system and the system arc flash risk at this time.

They also provided the system maximum guaranteed short circuit current. This value should be considered whenever the facility is purchasing new equipment for the facility to assure that the new equipment will meet the fault current carrying requirements of the present and possible future system. As always, SSOE advises the VAMC to verify the utility values when system changes are made by the utility to guarantee proper equipment rating. These values and a letter with explanations are shown on Appendix SC-C.

An electronic copy of the complete short circuit study of the Base Scenario (existing conditions) as reported by SKM Power*Tools is included on the accompanying CD.

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Appendix SC A – Electrical Utility Fault Current Information

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Appendix SC B – 3-Phase Short Circuit Report

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Excel pd appraisal

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Appendix SC C – Short Circuit One-Line Diagrams

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SC001

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SC002

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SC003

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4.0 Arc Flash Hazard

In order to properly accomplish the Arc Flash Hazard Analysis, four steps were completed by SSOE Group. First, existing system information was accumulated from existing documents and field investigation. The system was then entered into an electrical modeling computer program (SKM Systems Analysis Software) in a one line diagram format. The data entered included transformers, motors, protective devices and cables and lengths.

Third, an electrical short circuit study was completed to establish the available fault current at each point of application or bus. The system protective device coordination was evaluated. The existing condition was documented and changes are recommended to improve coordination. Then the arc flash hazard study was completed to evaluate the arc hazard levels for personnel that may be operating and/or working on the electrical power distribution system while it is energized. After this was completed the system was reviewed for voltage stability, the emergency power system was reviewed, the condition of the ground system was considered and the overall condition of the distribution system was evaluated.

4.1 Scope of Work

The scope of work for this project was to perform an Arc-Flash Hazard Analysis for the Overton Brooks VA Medical Center in Shreveport, LA. The study was to encompass the entire electrical system (both normal and emergency) from the incoming utility main transformers and emergency generators, and continue through to each branch circuit panel board, motor control center or motor control panel in each building.

In order to properly accomplish the Arc Flash Hazard Analysis, three studies were completed. First, an electrical short circuit study was done to evaluate the electrical components’ withstand and interrupting ratings versus the available fault current at their point of application. Second, a protective device coordination study was done to evaluate the order of operation of the protective devices in the event of overloads and faults. Third, the arc flash hazard study was done to evaluate the arc hazard levels for personnel that may be operating and/or working on the electrical power distribution system while it is energized.

4.2 Introduction

SKM Power Tools for Windows Software from SKM Systems Analysis, Inc. was used for the studies listed in the Scope of Work. The calculation method used within SKM was the industry’s preferred method of IEEE 1584 – 2002/2004a Edition (NFPA 70E 2012 Annex D.7).

The starting point of the arc flash analysis was a field trip to the VAMC facility in Shreveport, Louisiana where SSOE verify the VA provided documents and developed a complete set of one lines with sufficient data to evaluate the power system. All studies were done using standard practices recognized by IEEE, NFPA, and the

NEC.

4.3 Discussion

OSHA’s basic requirement is that work should not be done on exposed live parts above 50-volts. They do recognize that there are tasks encountered during construction, testing and maintenance that do require work around or on exposed live parts. An arc flash hazard analysis identifies the arc flash hazard present when work has to be completed on or around exposed live parts. Only qualified persons should be within the boundaries outlined below when there are exposed live parts. A qualified person is: “One who has skills and knowledge related to the construction and operation of the electrical equipment and installations and has received safety training to recognize and avoid the hazards involved.”(NFPA 70E) Non- qualified persons are only allowed within these boundaries when they are using the same level of PPE and under the supervision of a qualified person.

Whenever possible, de-energize equipment before working on or around electrical parts. This should be the highest priority. It should be noted that PPE is required to confirm that the electrical parts are de-energized.

Arc Flash Personal Protective Equipment (PPE) Class is based on calculations as defined in IEEE 1584 and

Electrical System Assessment 68 definitions per NFPA 70E tables. The standard table is table 130.7 (C) (16) of the 2012 NFPA70E, and is included in this report. The PPE categories range from 0-4 with Category 0 being basic cotton clothing and Category 4 being multiple layers of fire rated clothing. There is another possible category and that is any arc energy above the PPE Category 4 level. This is identified as “Dangerous” in this report. No work should be done around live parts on equipment designated with a PPE Category of “Dangerous”. Appendix A and Appendix B contain the Arc Flash data. The tables are organized alphabetically by bus name.

There are two appendices attached to this section of the report. Appendix A is the arc flash tables. These show the arc flash risk category, the arc incident energy, and the arc flash boundary at each piece of evaluated equipment, as well as the data that supports these values. Appendix A values are based upon the normal power source with Utility company stipulated values. Appendix B includes the Arc Flash One Lines. These one lines show the arc flash risk category at each piece of evaluated equipment, as well as the available short circuit current at that equipment, and the system information. The system information includes transformer, cable, and protective device information. Appendix B values are based upon the normal power source. The tables are helpful for the experienced interpreter, but the Arc Flash One Lines are the most practical help for the typical user.

Obviously there should be a goal to keep the arc flash hazard as low as possible. Most users have found the PPE requirements of PPE Category 0, 1, and 2 to be functional. The clothing and other PPE requirements are not significantly different than normal protective equipment that would be expected. There are three other possible PPE categories (3, 4, and Dangerous) these require significantly more PPE, and there are other hazards associated with these levels of energy that most users want to avoid.

As seen in the appendices, PPE categories are independent of voltage. The main factors to determine the severity of arc flash exposure is (1) proximity of worker to energize equipment (2) short circuit current levels and

(3) duration time of short circuit before interruption of the fault current.

There can be conditions in the electrical configuration that would allow a fault condition to exist for several seconds. However, IEEE 1584 identifies that a maximum exposure time of 2 seconds can be utilized during arc flash hazard evaluation, if the affected personnel can get away from the arc in the event of an incident. This maximum time is utilized because there are consequences of an arc blast or human reflex reaction to an arc flash condition that would typically prevent longer exposure. As part of a fault condition, the blast pressure can be substantial enough to move a person across a room and out of the arc flash boundary. In addition to the blast pressure, reflex reaction will occur almost subconsciously making the person jump for safety and remove themselves from a dangerous situation. This 2 second limit was implemented in this study, because there are no normal instances of service or maintenance in your systems that would hold an individual in the flash protection boundary longer than 2 seconds.

As noted above, the arc flash hazard at any one device is dependent upon a number of factors. These factors can vary at the device based upon the electrical source feeding the equipment at the time. Lower than normal utility contribution currents might be present during certain situations. This can be good, if the lower fault current is interrupted quickly. There are times that the lower fault current takes considerably longer time to clear, therefore the arc flash hazard at a device may be higher during periods of lower contribution currents in the system than it is with the normal operation. This has been taken into account in your study. The arc flash hazard has been calculated for the normal power source to impacted equipment and for the scenario when less than expected values from the power source feed to the same equipment. Arc flash labels always reflect the worst case condition. That is, the arc flash hazard at a panelboard may be risk category 0 from the normal power source, but risk category 3 from the lower contribution current of the source. The label applied to that panelboard indicates the higher risk.

When determining the arc flash information using this report, the user should review the specific information shown on the one lines in Appendix B. For the lower contribution current, no drawings were included, but the values obtain were the result of a hypothetic scenario included with the electronic file. The user should utilize the highest level of PPE for the respective equipment.

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Personal Protective Equipment is required any time energized electrical equipment will be operated (switch breaker) or exposed, including opening of equipment doors for observation, infrared analysis, or voltage and/or current measurements. A listing of typical tasks is available in table 130.7(C) (15) (a) in the 2012 NFPA70E and is not included in this report.

Personal Protective Equipment (PPE) Personal protective equipment shall provide protection from hazardous electrical conditions. Personal protective equipment shall include one or more of the following as determined by authorized management:

Shoes, boots, or overshoes for wet service

Gloves for wet service

Sleeves for wet service

Shoes for dry service

Gloves for dry service

Sleeves for dry service

Electrically insulated head protection

Protective clothing

Hearing Protection

Eye protection

Testing of Personal Protective Equipment Personal protective equipment shall be verified with regularity and by methods that are consistent with the exposure of employees to hazardous electrical conditions.

Definitions per the 2012 NFPA 70E are listed below. These distance boundaries are important for personnel protection from arc flash hazards in addition to electrical shock hazards.

Arc Flash Boundary The arc flash boundary for systems 50 volts and greater shall be the distance at which the incident energy equals

1.2 cal/cm2.

Limited Approach Boundary An approach limit at a distance from an exposed energized electrical conductor or circuit part within which a shock hazard exists.

Restricted Approach Boundary An approach limit at a distance from an exposed energized electrical conductor or circuit part within which there is an increased risk of shock, due to electrical arc over combined with inadvertent movement, for personnel working in close proximity to the energized electrical conductor or circuit part.

Prohibited Approach Boundary An approach limit at a distance from an exposed energized electrical conductor or circuit part within which work is considered the same as making contact with the electrical conductor or circuit part.

4.4 Assumptions

During the course of performing an arc flash study, various assumptions must be made when exact information is not available or when the use of exact information would not contribute to greater accuracy of the results.