Dredge Jadwin Arc Flash Hazard Analysis.pdf

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TAI 1200ARC FLASH HAZARD ANALYSIS U.S ARMY CORPS OF ENGINEERS

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List of Effective Pages

Dates of issue for original and changed pages are:

Original: Rev P0 Date: 3-16-18

Total number of pages in this publication is 157

Revision Record

Revision Date Title and/or Brief Description Signature

P0 3/16/18 Preliminary Issue SK/AK

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General Notes

The results and recommendations of this analysis are intended to identify Personal Protective Equipment (PPE) requirements and Arc Flash Boundaries (AFB) to be observed ONLY when there is not a substitution for working on energized equipment or circuit parts.

The results and recommendations of this analysis will not provide complete protection from all arc flash hazards. The calculations used in this analysis to determine AFB and PPE requirements are only intended to protect individuals exposed to live parts from receiving a second‐degree burn resulting from an arc flash blast.

The results and recommendations of this analysis do not imply that personnel be permitted to work on exposed energized equipment or circuits. OSHA restricts the situations in which work is to be performed near or on energized equipment or circuits by stating, “Live parts to which an employee may be exposed shall be de‐energized before the employee works on or near them, unless the employer can demonstrate that de‐energizing introduces additional or increased hazards or is infeasible due to equipment design or operational limitations.”

The results and recommendations of this analysis are valid only for the operating scenarios and plant configuration(s) shown in this report. If changes are made to the electrical system such as but not limited to the addition or removal of equipment, the reconfiguration of loads, changes to protective device settings, additional modes of operation, then the results and recommendations of this report are not valid and the analysis must be reevaluated.

In accordance with ER 385‐1‐100, it is the facility manager’s responsibility to have this analysis updated when any major modifications or renovations are made to the electrical system. The analysis shall be reviewed every five years (at maximum) to account for changes in the electrical distribution system that could affect the results of this analysis.

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Table of Contents

1. EXECUTIVE SUMMARY

2. INTRODUCTION

3. BACKGROUND

4. ARC FLASH HAZARD PROGRAM

5. ASSESSMENTS

6. SYSTEMS COVERED BY IEEE STD. 1584

7. MITIGATING HAZARDS

8. DETAILED INCIDENT ENERGY AFH ANALYSIS PROCEDURE

8.1 STEP‐1: DATA COLLECTION

8.2 STEP‐2: IDENTIFY PLANT’S VARIOUS OPERATING SCENARIOS

8.3 STEP‐3: SYSTEM MODELING

8.4 STEP‐4: SETTING USER‐DEFINED ARC FLASH PARAMETERS

8.5 STEP‐5: CREATE AND STORE PLANT’S OPERATING SCENARIOS

9. ARC FLASH HAZARD ANALYSIS

10. ASSUMPTIONS

11. OPERATING SCENARIOS EVALUATED

12. COMPUTER PRINTOUT HEADING DESCRIPTIONS

13. RESULTS SUMMARY

14. RECOMMENDATIONS

15. DEFINITIONS

16. ATTACHMENTS

List of Tables

Table 1-1: Summary of Arc Flash Hazard Results Table 6-1: IEEE Std. 1584 Distribution of Arc Flash Test Data Table 8-1: IEEE Std. 1584 Equipment Classes and Typical Working Distances Table 9-1: NFPA 70E Arc Flash PPE Levels Table 11-1: Operating Scenarios Evaluated Table 12-1: EasyPower Example Computer Printout

List of Figures

Figure 10-1: Line Side vs. Load Side

EXECUTIVE SUMMARY

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1. EXECUTIVE SUMMARY

Technology Associates, Inc. has been contracted to perform Arc Flash Hazard analysis for USACE Dredge Jadwin.

Table 1-1 shows the summarized results of this Arc Flash Hazard Analysis. There are two locations where the incident energy exceeds the maximum hazard risk category of 40.0 cal/cm2. No live work is to be permitted at these locations unless a Standard Operating Procedure (SOP) is developed to reduce the hazard risk category to an acceptable level. These locations include the 600 V Switchboard and 480-208/120V Shore Power Transformer secondary side. Please refer to the Results Summary section in Attachments 15&16 for detailed findings.

Category Description Incident Energy

Rating Number of

Devices

4.0 cal/cm2 Arc-rated FR Shirt & Pants, Hardhat, Safety Glasses or Goggles <4.0 cal/cm2 63

8.0 cal/cm2 Arc-rated FR Shirt & Pants, Hardhat, Safety Glasses or Goggles 4.0-8.0 cal/cm2 4

25.0 cal/cm2 Arc-rated FR Shirt & Pants & Arc Flash Suit, Hardhat & FR Hardhat Liner, Safety Glasses or Goggles 8.0-25.0 cal/cm2

40.0 cal/cm2 Arc-rated FR Shirt & Pants, Arc Flash Suit, Hardhat

& FR Hardhat Liner, Safety Glasses or Goggles 25.0-40.0 cal/cm2

Extreme Dangerous

Extreme Danger! No FR Category Found, Do not work on Live! >40.0 cal/cm2 2

Table 1-1: Summary of Arc Flash Hazard Results

2. INTRODUCTION

An Arc Flash Hazard (AFH) is defined as a dangerous condition associated with the possible release of energy caused by an electric arc. An AFH may exist when energized electrical conductors or circuit parts are exposed, or when they are within equipment in a guarded or enclosed condition, provided a person is interacting with the equipment in such a manner that could cause an electric arc. Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an AFH.

Employees working on energized electrical equipment, operating at 50 volts or more, have the potential for injury from arcing faults by conditions such as un‐insulated tools contacting electrical buses, insulation failures, loose connections, improper work procedures, impurities or dust buildup, corrosion, condensation, over‐voltage conditions, improperly maintained electrical equipment, or equipment malfunctions. Arcing faults produce hazards of extreme temperatures, light, sound, and pressure.

The complete mitigation of AFHs is not possible in all cases. The most effective method to mitigate an AFH is to de‐energize electrical equipment before examination, adjustment, servicing or maintenance of the equipment. Only trained, qualified, and properly equipped personnel should be near exposed, energized equipment. The calculations and recommendations of applicable standards and these procedures do not guarantee complete protection from AFHs. However, compliance with these procedures will reduce the possibility of burns and other injuries. Personnel that work in USACE facilities must be adequately protected from the risk of exposure to electric energy (EP 385‐1‐100 Para. 3).

BACKGROUND

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3. BACKGROUND

Shock and electrocution have long been recognized as risks to those who work with electricity. In recent years, additional emphasis has been placed on the dangers associated with arc flash and arc blast energy. This risk arises, not from the passage of electric current through the body, but from the concentrated energy during an arcing fault.

An electric arc can instantly vaporize material such as copper or steel. The arc, passing through the vaporized material, can create an extremely bright AF of very high and dangerous temperatures. The result could be severe burns to the hands, face, and body; hearing loss; physical trauma from blast pressure; and possible death.

In 1979, the National Fire Protection Association (NFPA) introduced NFPA 70E, Standard for Electrical Safety in the Workplace. This standard covers methods of protecting workers from harm due to exposure to electrical systems and devices. In 1995, NFPA 70E was revised to help protect individuals from AF dangers.

The USACE Safety and Health Requirements Manual, EM 385‐1‐1, 2003 added requirements for an AFH analysis to be conducted in accordance with NFPA (EP 385‐1‐100 Para. 4).

4. ARC FLASH HAZARD PROGRAM

Department of the Army – USACE HQ added the Arc Flash Hazard Program to the safety regulation, ER 385‐1‐100. The regulation applies to all USACE operated facilities where the potential for AFH exists. This includes, but is not limited to, recreational facilities, hydropower facilities, spillways, navigation facilities, flood control (flood damage reduction) facilities, floating plant, fish facilities, pumping stations, irrigation and domestic water facilities, maintenance shops, offices, laboratories, remote communications sites, and transportable or mobile equipment (ER 385‐1‐100 Chapter 1, Para. 1‐2).

The AFH Program is a portion of a total Electrical Safety Program that includes electrical safe working practices.

The AFH Program includes policies, practices, documentation, and standard operating procedures (SOPs) (EP 385‐1‐100 Para. 5a).

An AFH analysis is required if there is a possibility that employees may be exposed to energized electrical equipment with AC or DC voltages of 50 volts to ground or more. The AFH analysis shall be reviewed periodically, not to exceed five years, to account for changes in the electrical distribution system that could affect the results of the AFH analysis. There are two forms of AFH analyses: Task Based Assessment and a Detailed Incident Energy (IE) Analysis (EP 385‐1‐100 Para. 6).

The Task Based Assessment should be used as an interim step, to protect employees, at all facilities until a Detailed IE Analysis is able to be funded and completed, for up to a maximum of two years from the effective date [of the EP 385‐1‐100 – 1 October 2014], at which point a Detailed IE Analysis must have been completed (EP 385‐1‐100 Para.

6.a.(1)).

5. ASSESSMENTS

NFPA 70E and IEEE Std. 1584 have developed methods and equations for determining the arc flash hazard at specific locations throughout a facility’s electrical system. Task based assessments as well as detailed incident energy analyses are both used to identify the arc flash boundary (AFB), hazard risk category and PPE requirement at each location within the electrical system.

SYSTEMS COVERED BY IEEE STD. 1584

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The NFPA 70E Task Based Assessment assigns a prescriptive PPE category based on the equipment voltage and the nature of the task being performed. The major drawback to this approach is either too much or too little protection is identified. Since the short circuit current and protective device settings are not used to determine the hazard risk category, assumed short circuit currents and maximum clearing times are used to approximate the worst‐case hazard based on the system voltage.

The IEEE Std. 1584 Detailed IE Analysis provides equations to calculate the arc flash boundary and incident energy at particular locations within the facility’s electrical system. The equations use the available three phase short circuit current, protective device clearing times, typical bus gap, working distance and system voltage at each location to determine the IE exposure to the worker, the AFB, hazard/risk category, and required PPE.

Although the IEEE Std. 1584 Detailed IE Analysis approach is much more accurate and preferred over the NFPA 70E Task Based Assessment, it is a relatively new method for calculating the hazard risk category, IE and AFB.

These equations are derived from theory and the research involving arc flash incident energy measurements conducted in a controlled test environment. Therefore, results derived from the IEEE equations may be more or less severe than the hazard of an actual arc flash event.

The intent of the NFPA 70E and IEEE Std. 1584 assessments is to establish standard practices for determining the boundary and the PPE category necessary to protect the worker from the onset of a second degree burn. The threshold energy for a second degree burn is 1.2 cal/cm2.

The calculations do not account for the hazards associated with the arc explosion itself. Splattering of molten metal, explosion propelled debris and high pressure shock waves are hazards that are not accounted for in the calculations.

These additional hazards should be considered by the facility’s safety manager when developing SOP’s.

6. SYSTEMS COVERED BY IEEE STD. 1584

Due to a limited amount of test data on controlled arc flash incident energy measurements; the IEEE Std. 1584 equations are only applicable to electrical systems having the following:

Voltages of 208 V – 15,000 Volts, three phase Three phase bolted short circuit current of 700 Amps – 106,000 Amps Frequencies of 50 or 60 Hz

Conductor gaps of 13 mm – 152 mm 208 Volt systems fed by transformers >125 kVA

Of the controlled incident energy tests performed at voltages less than 1 kV, very few measurements have been taken below 250 Volts. The following table shows a distribution of the test data used to develop the low voltage IEEE Std. 1584 equations.

MITIGATING HAZARDS

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Tests

LV (kV) Performed Percentage

0.208 kV 1 1%

0.25 kV 5 3%

0.4 kV 36 22%

0.45 kV 3 2%

0.488 kV 3 2%

0.59-0.623 kV 111 68% 0.68-0.768 kV 4 2%

Table 6-1: IEEE Std. 1584 Distribution of Arc Flash Test Data

IEEE Std. 1584‐2002, Section 4.2 Step 1 states “Equipment below 240 V need not be considered unless it involves at least one 125 kVA or larger low‐impedance transformer in its immediate power supply or the arc flash contribution equals or less than 10 kA.” Section 9.3.2 further states “The arc‐flash hazard need only be considered for large 208 V systems: systems fed by transformers smaller than 125 kVA should not be a concern.”

Of the IEEE low voltage test data, the longest self‐sustaining arc lasted approximately two seconds. The bolted short circuit current measured was 700 Amps at 600 volts. The test data indicates that the arc duration is determined by the voltage and the bolted short circuit current. In conclusion, low voltage and low short circuit current arc flash events are unlikely to self‐sustain for more than two seconds.

7. MITIGATING HAZARDS

Once the AFH analysis or assessment is complete, mitigation techniques will be incorporated. There may be scenarios identified that are either not covered or are in a category rating above the maximum value that can be mitigated by Protective Clothing and Personal Protective Equipment (PPE). To deal with these situations the facility will need to develop a mitigation plan to address the specific hazard (EP 385‐ 1‐100 Para. 5.b.).

Hierarchy of controls shall be used to remove, reduce, or achieve an acceptable level of risk. The control strategies list the substitution and elimination of hazards as the first steps towards meeting the commitment to providing a safe workplace. Lower‐tiered strategies are then considered in descending order of effectiveness, until workers are adequately protected. The mitigation of arc flash hazards is best achieved by a combination of controls in which PPE is always considered last.

AFH Mitigation on floating plant may become infeasible due to plant configuration and confined areas (e.g.

switchboards on vessels are in the pilot house with the Captain/operator). These situations shall be identified. When mitigation methods cannot bring risk to an acceptable level, an SOP must be developed that details how the crew will deal with these situations. These situations should not pose an AFH during normal operating conditions but do during maintenance. For AF hazards on U.S. Coast Guard inspected USACE Floating Plant, hazard mitigation must not violate applicable USCG protective device coordination requirements, thereby maintaining the reliability of the vessel’s electrical power and distribution systems (EP 385‐1‐100 Para. 7.a.).

DETAILED INCIDENT ENERGY AFH ANALYSIS PROCEDURE

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8. DETAILED INCIDENT ENERGY AFH ANALYSIS PROCEDURE

This Detailed IE Arc Flash Hazard Analysis was conducted in accordance the EP 385‐1‐100 and ER 385‐1‐ 100 as well as NFPA 70E and IEEE Std. 1584. The process for performing this analysis is as follows:

8.1 STEP‐1: DATA COLLECTION

The greatest single effort in completing a detailed IE AFH analysis is the data collection of the electrical system.

This task involves obtaining up to date one‐line diagrams, short circuit studies, protective device coordination studies and manufacturer datasheets. In the absence of these documents, it is necessary to validate the one‐line diagram and collect all necessary data from the field needed to complete the analysis. The data required to complete a detailed IE analysis includes but is not limited to plant configuration information such as system voltage, grounding configuration, one‐line model; all protective device information, i.e. circuit breaker trip ratings, dial settings, fuse ratings, protective CTs and relays; all impedance data, i.e. utility service X/R ratios, generators, transformers, motors, cables, transmission lines; specific arc‐flash data, i.e. equipment type, equipment class, gap between buses and conductors, whether conductors are enclosed or in open air and cableway type.

8.2 STEP‐2: IDENTIFY PLANT’S VARIOUS OPERATING SCENARIOS

Depending on the specific mission of the facility, the electrical system may be set up to function in various modes of operation to maximize efficiency and reduce operating costs. These modes of operation may include:

Multiple utility sources used for various demands Multiple generators operating in parallel or in standby Automatic power transfer from backup generators for emergency operations Interlocked utility and generator feeders Operation of bus tie circuit breakers Switchboards and MCCs fed from multiple sources Reduced load maintenance modes

Reducing the connected motor load is a common practice for lowering short circuit current for the maintenance of energized equipment; however this changes the trip characteristic of the upstream circuit breakers and fuses. As the short circuit current is decreased, the clearing time of those protective devices is increased, which in turn can have a significant impact on the incident energy level and the PPErequirement at each point in the system. Each possible scenario must be identified in order to determine the worst‐case condition.

8.3 STEP‐3: SYSTEM MODELING

There are various engineering software packages available that may be used to perform AFH analyses. SKM System Analysis, Inc.’s Power*Tools and ESA EasyPower are two common power system analysis software packages used to complete AFH analyses. This analysis was conducted using the EasyPower software package. In accordance with NFPA 70E and IEEE Std. 1584, the EasyPower power system analysis program provides the equations to perform the necessary AFH analysis calculations.

Once the data collection is complete and operating scenarios are identified, the electrical system model is the next step in performing the detailed IE AFH analysis. The model is comprised of the electrical system one‐line diagramwith all specific equipment and plant configuration data from steps 1 and 2 above. Creating an accurate

DETAILED INCIDENT ENERGY AFH ANALYSIS PROCEDURE

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model is vital to ensure that the most realistic results are obtained. The results of the analysis are only as good as the model.

Using accurate short circuit currents and modeling exact protective device clearing times is extremely important in obtaining reliable AFH results. Using conservative (high) short circuit current values could yield faster protective device clearing times, depending on the protective device specific time current curve, making the IE and AFH less than a longer clearing time and lower magnitude short circuit event.

8.4 STEP‐4: SETTING USER‐DEFINED ARC FLASH PARAMETERS

Prior to running the calculations for the AFH analysis, the user must determine the calculation standard and other parameters that the study will be based on. The user defined parameters include calculation standard, working distance, units of measure and threshold incident energy.

EasyPower provides four calculation standards, IEEE Std. 1584, NFPA 70E (2009), and EasyPower enhanced versions (V9.0). The user may choose to use a calculation standard of choice; however the IEEE Std. 1584 standard is preferred and has been selected for this AFH analysis.

The degree of injury from an arc flash burn depends on the percentage of a person’s skin that is burned, and the critical nature of the burn. Since the head and body make up a large percentage of the total surface area and since these areas are much more critical to survival than the arms and hands, the working distance has been defined as the distance between the possible arc point and the head and body of the worker performing the task.

When using EasyPower to perform AFH analyses, the typical working distances shown in Table 8-1 are used as the default setting. EasyPower provides five working distances for each class of equipment to allow the user to select a working distance that fits the need of the facility. Table 8-1 shows the IEEE Std. 1584 typical working distances for the various classes of equipment.

Type/Class of Equipment Typical Working distance inches Distance X Factor Open air/cable 18 2.0

Low-Voltage MCCs and Panelboards 18 1.641 Low-Voltage Switchgear 24 1.473

5-Kilovolt Switchgear 36 0.973 15-Kilovolt Switchgear 36 0.973

Table 8-1: IEEE Std. 1584 Equipment Classes and Typical Working Distances

EasyPower is capable of displaying calculated results in various units of measure for arc flash boundaries and working distances. Available units of measure include inches, feet, mm, cm, and meters. The user should select the appropriate unit of measure to make the AFH distances easy to recognize by the workers of the facility.

EasyPower provides options for the user to select threshold IE levels for various voltage ranges. When thresholds are set, devices that exceed the set value will be highlighted on the one‐line model indicating danger. This allows facility safety managers to set and easily identify locations where the IE magnitudes are above the desired levels.

ARC FLASH HAZARD ANALYSIS

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8.5 STEP‐5: CREATE AND STORE PLANT’S OPERATING SCENARIOS

EasyPower has a built‐in feature that allows the user to evaluate multiple operating scenarios simultaneously to identify the plant’s worst‐case hazard. Using EasyPower’s Scenario Manager, the user must first create a base case one‐line model or save an existing one‐line as the base case to be evaluated. Once the base case is complete and stored, the user may begin creating the various operating scenarios a plant may have. This is done by opening and/or closing circuit breakers to connect and disconnect sources and loads from the rest of the plant. Each variation of the base case must be stored as a separate scenario.

9. ARC FLASH HAZARD ANALYSIS

For this analysis, the AFH calculations were conducted using the IEEE Std. 1584 equations with the EasyPower software package. The IEEE Std. 1584 equations are known to produce more conservative results than the other methods, therefore requiring higher categories of PPE. The various categories of PPE are base on the level of incident energy available at each piece of equipment and are prescribed from NFPA 70E. Table 9-1 shows the different PPE categories based NFPA 70E.

Hazard/Risk Category

Description Min. Arc Rating

(Cal/cm2)

Arc-rated Long-Sleeve Shirt Arc-rated Pants or Overall Arc-rated Face Shield with Hard Hat Safety Glasses Hearing Protection Leather & Voltage-rated gloves (as needed) Leather Safety Shoes

4.0

Arc-rated Long-Sleeve Shirt Arc-rated Pants or Overall Arc-rated Face Shield & Balaclava or Arc Flash Suit with Hard Hat Safety Glasses & Hearing Protection Leather & Voltage-rated gloves (as needed) Leather Safety Shoes

8.0

Arc-rated Long-Sleeve Shirt Arc-rated Pants Arc-rated Flash Hood with Hard Hat Safety Glasses & Hearing Protection Leather & Voltage-rated gloves (as needed) Leather Safety Shoes

25.0

Arc-rated Long-Sleeve Jacket Arc-rated Pants Arc-rated Flash Hood with Hard Hat Safety Glasses & Hearing Protection Leather & Voltage-rated gloves (as needed) Leather Safety Shoes

40.0

Table 9-1: NFPA 70E Arc Flash PPE Levels

ASSUMPTIONS

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10. ASSUMPTIONS

The results of this AFH analysis are based upon the following assumptions.

1. IEEE Std. 1584 equations were applied for all AFH calculations using the EasyPower software package.

2. The working distances used for this analysis were based on Table 8-1 – IEEE Std. 1584 Equipment Classes and Typical Working Distances.

3. For this analysis, ANSI was the X/R calculation method used for all motors and transformers.

4. IEEE Std. 1584 Section 9.3.2 states “The arc‐flash hazard need only be considered for large 208 V systems:

systems fed by transformers smaller than 125 kVA should not be a concern.” For this analysis, a 0.5 second maximum arc time was used for all equipment <120 V served by transformers <125 kVA. By setting a maximum trip time of 0.5 seconds, the loads downstream of the transformer will be considered so that AF labels can be produced for each piece of equipment without affecting the total short circuit current for the electrical system.

5. Of the IEEE low voltage test data, the longest self‐sustaining arc lasted approximately two seconds. The data indicates that low voltage and low short circuit current arc flash events are unlikely to self‐sustain for more than two seconds. For this analysis, a 2.0 second maximum arc time was used for all equipment <600 V served by transformers >125 kVA.

6. For electrical equipment with a main overcurrent protection device, the user must choose between two incident energy values. These values are known as Line‐Side and Load‐Side incident energies. See Figure

1. The line‐side IE value is normally higher than the load‐side value since the next upstream overcurrent protective device typically has a greater interrupting time and rating. Therefore, when the line‐side IE value is chosen, the PPE requirements are more stringent than the required level of protection for the load‐side value. Choosing the higher value of the two will ensure that the worker is adequately protected for the worst‐case AF event. For this analysis, the line‐side incident energy values were used for all equipment with a main overcurrent protection device.

Figure 10-1: Line Side vs. Load Side

7. The Arc Flash Boundary is the distance from the origin of the arc itself where the incident energy equals

1.2 cal/cm2. NFPA 70E allows the AFB to be calculated at 1.5 cal/cm2 for instances where the protective device clearing time is less than 0.1 seconds. For this analysis, the AFB is the calculated distance where the incident energy equals 1.2 cal/cm2.

8. All motors were assumed to running at 100% during the AFH analysis.

9. All cables were modeled in steel tray and the lengths were approximated with assistance from the crew.

10. Since the shore power utility data was not available, the utility was assumed to be 300 MVA, 480VAC with a 6 X/R ratiofor 480V Switchboard and 300 MVA, 480VAC with a 6 X/R ratio with the utility transformers assumed to be 480 kV – 208 V 150 kVA with an impedance of 5.5% for 208/120V Switchboard.

OPERATING SCENARIOS EVALUATED

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11. OPERATING SCENARIOS EVALUATED

Table 11-1 is a matrix representing all possible modes of operation that were identified by the crew. The matrix shows the status of the protective devices used for each operating scenario. The X represents circuit breakers in the closed position.

The four generator circuit breakers (GEN-1 (GEN1 CB), GEN-2 (GEN2 CB), GEN-3 (GEN3 CB) and GEN-4 (GEN4 CB)) supply power to 600V MN SWBD bus and its loads in Operating-3 scenario. Two generator circuit breakers GEN-3 (GEN3 CB) and GEN-4 (GEN4 CB)) supply power to 600V MN SWBD bus and its loads in Operating-2, GEN-2 (GEN2 CB) and GEN-4 (GEN4 CB)) supply power to 600V MN SWBD bus and its loads in Operating-7 andGEN-1 (GEN1 CB) and GEN-4 (GEN4 CB)) supply power to 600V MN SWBD bus and its loads in Operating-8. One generator circuit breaker GEN-2 (GEN2 CB) supplies power to 600V MN SWBD bus and its loads in Operating-1, GEN-3 (GEN3 CB) supplies power to 600V MN SWBD bus and its loads in Operating-5, GEN-4 (GEN4 CB) supplies power to 600V MN SWBD bus and its loads in Operating-6 and GEN-1 (GEN1 CB) supplies power to 600V MN SWBD bus and its loads in Operating-4.

Shore power1 and Shore power2 circuit breaker supply power to Bus-x and its loads in Port-1 condition. One generator circuit breaker GEN-4 (GEN4 CB), Shore power1 and Shore power2 circuit breakers supply power to 480VAC MAIN SWBD bus and 208/120V MAIN SW bus and its loads in Port-2 condition. Generator circuit breaker GEN-3 (GEN3 CB), Shore power1 and Shore power2 circuit breakers supply power to 480VAC MAIN SWBD bus and 208/120V MAIN SW bus and its loads in Port-3 condition. Generator circuit breaker GEN-2 (GEN2 CB), Shore power1 and Shore power2 circuit breakers supply power to 480VAC MAIN SWBD bus and 208/120V MAIN SW bus and its loads in Port-4 condition.And generator circuit breaker GEN-1 (GEN1 CB), Shore power1 and Shore power2 circuit breakers supply power to 480VAC MAIN SWBD bus and 208/120V MAIN SW bus and its loads in Port-5 condition.

Table 11-1: Operating Scenarios Evaluated

COMPUTER PRINTOUT HEADING DESCRIPTIONS

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12. COMPUTER PRINTOUT HEADING DESCRIPTIONS

Tabel 12-1 shows an example of an EasyPower AFH analysis computer printout.

Table 12-1: EasyPower Example Computer Printout

The following column headings describe the results of the analysis.

Arc Fault Bus Name ‐The names in this column correlate to the names implemented in the software system model (reference the one‐lines are included in the Attachments section of this report). These locations correspond to plant equipment such as main switchboards, panelboards, transformer terminals, etc.

Worst Case Scenario – This column identifies the scenario that resulted with the worst‐‐case incident energy values.

Arc Fault Bus kV ‐The values in this column show the nominal line‐to‐line voltage for the faulted bus.

Upstream Trip Device Name ‐This column lists the name of the device primarily responsible for clearing a potential fault as the associated bus. These device names correlate to the system model.

Equip Type ‐This column indicates whether the equipment is switchgear, panel, cable or open air. The equipment type provides a default gap value and a distance exponent used in the IEEE incident energy equations.

Arc Gap (mm) – This column displays the spacing between the bus bars or conductors at each location.

Bus Bolted Fault (kA) ‐This column shows the calculated first‐cycle, symmetrical, three‐phase, bolted fault current available for each bus in kiloamps. This current value corresponds to the system operating conditions that will result in the worst‐case calculated value for incident energy.

Bus Arc Fault (kA) ‐This column displays the portion of calculated arcing fault currents for each bus in kiloamps that is contributed through the protective device. These values demonstrate a reduction in available fault current due to the arc resistance.

Trip Time (sec) ‐This column displays the length of time required by the protective device to trip in the presence of the calculated bus arc fault current. For low voltage breakers and fuses, this time represents the total clearing time of the device.

RESULTS SUMMARY

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Opening Time (sec) – This column displays the circuit breaker operating time. For fuses and low‐voltage breakers the operating time will be zero since the fuse timing is already taken in account in the trip time column.

Arc Time (sec) – This column is the sum of the device tripping time and the circuit breaker opening time. This time represents the arcing fault duration which is used in the incident energy calculations.

Est Arc Flash Boundary (inches) – This column displays the distance within which a person must be clothed in the appropriate PPE. It is a limited approach distance from live parts that are exposed, within which a person could receive a second‐degree burn. More specifically, it is the distance from the origin of the arc itself where the incident energy equals 1.2 cal/cm2.

Working Distance (inches) – This column shows the typical distance from the live parts to the head and body of the worker performing the assigned task.

Incident Energy (cal/cm2) ‐Based on the arcing fault current, the total clearing time of the protective device, the bus bar gap, the grounding method, and the typical working distance, the column displays the results of the arc flash calculations at the reference location. This energy level directly corresponds to the appropriate PPE described in the Required Clothing Class column.

Required Clothing Class ‐These categories are specified in NFPA‐70E and correspond directly to the potential incident energy calculated for each location. Refer to Table 8-1 for suggested PPE for the Class ratings listed in Attachments 3 and 4.

13. RESULTS SUMMARY

There are two locations where the worst‐case incident energy exceeds the maximum hazard risk category 4. The 600 V Switchboard and 480-208/120V Shore Power Transformer secondary side are enclosures where the incident energy exceeds 40.0 cal/cm2. These enclosures are identified in Attachments 15 and 16 as Extreme Danger, meaning there is not PPE rated for these incident energy levels. No live work is to be permitted at these locations for the scenarios identified as Extreme Danger. Attachment 15 shows the worst‐case scenario AF results while Attachment 16 shows all scenario AF results.

At the 600 V Switchboard bus, the high incident energy of 43.1 cal/cm2 is due to the large short circuit current contribution from the ship service generators. This incident energy is calculated with all four generators online (Operating‐3 scenario). The 600 V Switchboard has single operating scenario (Operating‐3) with energy exceeding hazard risk category 4 as the worst‐case scenario.

At the Shore power transformer secondary side (P206 LV SH PR TX), the high incident energy of 190.9 cal/cm2 is due to the high short circuit current contribution from the shore power connection of the utility.

This incident energy is calculated with the shore power breaker and Genset 2 CB closed (Port-4 Scenario).

The Shore power transformer secondary side has five operating scenarios (Port-1, Port-2, Port-3, Port-4 and Port-5) with energies exceeding hazard risk category 4, with Port-4 as the worst‐case scenario.

Other locations with high incident energies include 600 V Generator No.1has an incident energy of 39.6 cal/cm2, 600 V Generator No.2has an incident energy of 39.7 cal/cm2, 600 V Generator No.3has an incident energy of 39.7 cal/cm2 and 600 V Generator No.4has an incident energy of 31.9 cal/cm2making the hazard risk category at these enclosures category 4. 480 V Transformer TX-3 primary side(P608-600VAC TX P)has an incident energy of 9.2 cal/cm2 and 480V Shore power outlet#1 has an incident energy of 13.3 cal/cm2 making the hazard risk category at these enclosures category 3. Table 9-1 for the appropriate PPE requirements for these locations.

RECOMMENDATIONS

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The remaining locations have low incident energies (< 8.0 cal/cm2) making the hazard risk category at the enclosures Category 2 or less. Four enclosures require Category 2 PPE and 63 enclosures require Category 1 PPE.

Refer to Attachment 16 for the complete list of enclosures and required PPE class.

14. RECOMMENDATIONS

The USACE Engineering Pamphlet (EP 385‐1‐100) recognizes that AFH mitigation on floating plant may become infeasible due to plant configuration and confined areas. Furthermore, hazard mitigation on U.S. Coast Guard inspected USACE floating plant, must not violate applicable USCG protective device coordination requirements, thereby maintaining the reliability of the vessel’s electrical power and distribution systems (EP 385‐1‐100 Para.

7.a.). When mitigation methods cannot bring risk to an acceptable level without violating USCG requirements, an SOP must be developed that details how the crew will deal with these situations.

For the two locations with incident energies in excess of 40.0 cal/cm2, no live work shall be permitted at these enclosures for the operating scenarios identified as Extreme Danger in Attachment 8. If live work is absolutely necessary at these enclosures to test for voltage, make load measurements, etc, then an SOP shall be developed by the facility manager to mitigate the hazard in accordance with EP 385‐1‐ 100 Para. 5.b and Para. 7.a.

The incident energy at the 600 V Switchboard can be reduced from 43.1cal/cm2 to 1.7 cal/cm2 by switching to the Operating-6 scenariowhich is within the PPE rating for hazard risk category 1.

The incident energy at the 480-208/120V Shore Power Transformer secondary side can be reduced from 190.6 cal/cm2 to 49.6 cal/cm2 by switching to the Port-1 scenario. Unfortunately, this does not reduce the hazard risk category at480-208/120V Shore Power Transformer secondary side; however it does decrease the magnitude of the potential hazard and reduces the AFB.

It is recommended that the same logic above be applied for the equipment with hazard risk categories 3 and 4 to limit the potential incident energy exposure to workers performing live work at these locations. The 600 V Generator No.1, 600 V Generator No.2, 600 V Generator No.3, 600 V Generator No.4, 480 V Transformer TX-3 primary side (P608-600VAC TX P)and 480V Shore power outlet#1has incident energies ranging from 39.7 cal/cm2 to 9.2 cal/cm2. Each of these enclosures has operating scenarios with lower short circuit current and incident energies. See Attachment 20.

The 600 V Generator No.1may be reduced from hazard risk Category 4 to Category 2 by switching to Operating‐4scenario.

The 600 V Generator No.2may be reduced from hazard risk Category 4 to Category 2 by switching to Operating‐1 scenario.

The 600 V Generator No.3may be reduced from hazard risk Category 4 to Category 2 by switching to Operating‐5 scenario.

The 600 V Generator No.4may be reduced from hazard risk Category 2 to Category 1 by switching to Operating‐6 scenario.

The 480 V Transformer TX-3 primary side may be reduced from hazard risk Category 3 to Category 1 by switching to any of the following operating scenarios: Operating‐1, Operating‐2 or Operating‐4 or Operating‐5 or Operating‐6 or Operating‐7 or Operating‐8 or Port-2 or Port-3 or Port-4 or Port-5.

The 480V Shore power outlet#1 may be reduced from hazard risk Category 3 to Category 2 by switching to Port-1scenario.

In addition to the above mentioned methods for reducing the hazard risk category of equipment with high incident energies, there are several other methods that may be considered. These methods include replacing outdated trip

DEFINITIONS

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units with faster clearing times devices, installing maintenance switches, andusing selective relaying with maintenance settings to clear faults faster when energized work is expected.

Note: Upon discussion with MDC we introduced breakers for each generator upstream 600V main switchboard to generate arc flash values in easy power, these breakers are not installed in vessel and we recommend these breakers be installed to have consistency between analysis and vessel installation.

15. DEFINITIONS

Arc Blast ‐A rapid gas pressure buildup caused by an arcing fault.

Arc Flash (AF) ‐A concentrated release of electric energy caused by an arcing fault.

Arc Flash Boundary (AFB) ‐When an arc flash hazard exists, an approach limit at a distance from a prospective arc source within which a person could receive a second degree burn if an electrical arc flash were to occur.

Arc Flash Hazard (AFH) ‐A dangerous condition associated with the release of energy caused by an electric arc.

An arc flash hazard may exist when energized electrical conductors or circuit parts are exposed or when they are within equipment in a guarded or enclosed condition, provided a person is interacting with the equipment in such a manner that could cause an electric arc. Under normal operating conditions, enclosed energized equipment that has been properly installed and maintained is not likely to pose an arc flash hazard. See NFPA 70E, Article 100.

Arc Flash Hazard (AFH) Analysis ‐A study investigating a worker’s potential exposure to arc flash energy, conducted for the purpose of injury prevention, the determination of safe working practices, and the appropriate level of PPE.

Arc Flash Related Incident and Accident ‐When an arc flash hazard exists, an incident and accident which involves an arc flash.

Arc‐rated (AR) ‐Refers to clothing or equipment and indicates that it has been tested for exposure to an electric arc.

Flame‐Resistant (FR) clothing without an arc rating has not been tested for exposure to an electric arc.

Arc Rating ‐The value attributed to materials that describe their performance to exposure to an electrical arc discharge. The arc rating is expressed in cal/cm2 and is derived from the determined value of the arc thermal performance value (ATPV) or energy of breakopen threshold (EBT) (should a material system exhibit a breakopen response below the ATPV value). Arc rating is reported as either ATPV or EBT, whichever is the lower value.

Arc Thermal Protection Value (ATPV) ‐Fire‐retardant rating by ASTM International. The ATPV for a piece of clothing or fabric is the minimum incident thermal energy that will cause the onset of a second‐ degree burn based on the energy transmitted through the clothing.

Breakopen ‐A material response evidenced by the formation of one or more holes in the innermost layer of arc‐rated material that would allow flame to pass through the material.

Category Dangerous ‐Levels above category 4 are determined as Category Dangerous. There is no approved PPE for this category.

Deenergized ‐Free from any electrical connection to a source of potential difference and from electric charge; not having a potential different from that of the earth.

Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this document.

EBT (Breakdown Threshold Energy) ‐The largest amount of incident energy that a garment can protect a worker from in cal/cm2 before the onset of second‐degree burns or before the garment breaks open and fails.

Exposed (as applied to live parts) ‐Capable of being inadvertently touched or approached nearer than a safe distance by a person. It is applied to parts that are not sufficiently guarded, isolated, or insulated from accidental contact or arc.

Flammable, Non‐FR Materials ‐Cotton, silk, rayon and wool fabrics. Although permitted within an AFB, these fabrics could ignite and continue to burn on the body, resulting in serious burn injuries.

Flammable, synthetic materials ‐These materials melt as a result of AF exposure conditions, form intimate contact with the skin and aggravate the burn injury (i.e., acetate, acrylic, nylon, polyester, polyethylene, polypropylene and spandex, alone or in blends shall NOT be used.

Flash Suit – A complete arc rated FR clothing and equipment system that covers the entire body, except for the hands and feet. This includes pants, jacket, and bee‐keeper‐hood fitted with a face shield.

Hazard/Risk Category Level ‐A number (level 0 through level 4) based on the energy released during an arcing fault. A Higher number indicates a higher energy level. The PPE needed to protect a worker is determined by the risk category level.

Incident ‐An unplanned event that did not result in injury, illness, or damage – but had the potential to do so.

Sometimes called a “close call” or “near miss”.

Incident Energy (IE) ‐The amount of energy impressed on a surface, a certain distance from the source, generated during and electrical arc event. One of the units used to measure incident energy is calories per centimeter squared (cal/cm2).

Insulated tools or equipment ‐Tools or equipment designed to provide insulation from an energized part or conductor. It may have conductive parts and be coated or covered by a dielectric material, or be composed entirely of insulating materials. Insulated industrial hand tools are typically stamped on the handle with an emblem (a double triangle) and a voltage rating. Such tools must be ASTM certified.

Limited Approach Boundary ‐An approach limit at a distance from an exposed live part within which a shock hazard exists. This boundary is also referred to as the safe approach distance in National Fire Protection Association (NFPA) 70E, “Standard for Electrical Safety in the Workplace,” Annex C.

Live Parts ‐Energized conductive components.

Natural Fibers ‐Fibers produced by natural processes, as opposed to manufactured synthetic fibers. Cotton, silk, and wool are examples of natural fibers. Rayon and nylon are examples of synthetic fibers.

PPE ‐See Protective Clothing and Personal Protective Equipment

Prohibited Approach Boundary ‐An approach limit at a distance from an exposed live part within which work is considered the same as making contact with the live part.

Protective Clothing and Personal Protective Equipment (PPE) ‐Items of arc‐rated clothing or equipment, that provide a barrier between an AF hazard and a worker. PPE consists of protective and arc‐rated (AR) clothing. For

Use or disclosure of data contained on this sheet is subject to the restriction on the title page of this document.

the purposes of this document, the term PPE will encompass protective clothing, arc‐rated clothing and personal protective equipment.

Qualified Engineer ‐An electrical engineer who has skills and knowledge related to the engineering and design of the electrical equipment and installations to include fault studies, coordination studies, arc flash studies.

Qualified Person (Electrical) ‐One who has received training in and has demonstrated skills and knowledge in the construction and operation of electrical equipment and installations and the hazards involved. This includes the skills and techniques necessary to distinguish exposed live parts from other parts of electric equipment, to determine the nominal voltage of exposed live parts, the clearance distances and corresponding voltages to which the qualified person will be exposed.

Note 1: Whether an employee is considered to be a “qualified person” will depend upon various circumstances in the workplace, e.g., an individual may be considered “qualified” with regard to certain equipment in the workplace, but “unqualified” as to other equipment.

Note 2: An employee who is undergoing on‐the‐job training and who, in the course of such training, has demonstrated an ability to perform duties safely at his level of training and who is under the direct supervision of a qualified person is considered to be a qualified person for the performance of those duties.

Restricted Approach Boundary ‐An approach limit at a distance from an exposed live 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 live part. This boundary is to be crossed by only qualified persons.

Working Distance (WD) ‐The dimension between the possible arc point and the head and body of the worker positioned in place to perform the assigned task. Working On (energized electrical conductors or circuit parts) ‐ Intentionally coming in contact with energized electrical conductors or circuit parts with the hands, feet, or other body parts, with tools, probes, or with test equipment, regardless of the personal protective equipment a person is wearing. There are two categories of “working on”:

1. Diagnostic (testing) is taking readings or measurements of electrical equipment with approved…