442-19-011S Electrical Coordination and Arc Flash Report 2020.pdf

Project 442-19-011S Electrical Coordination and Arc Flash Study

Report

1. Background The Cheyenne Veterans Affairs Medical Center (VAMC) was established in 1934 and serves

Veterans residing in Wyoming, western Nebraska, and northern Colorado. The last electrical coordination and arc flash hazard study for the Cheyenne VAMC campus was completed in

2014. This study is required every five years in accordance with VHA Directive 1028 - Electrical

Power Distribution Systems, and IEEE Standard 1584-2018 - IEEE Guide for Performing Arc-Flash

Hazard Calculations.

2. Project Objective Complete an electrical coordination and arc flash study for the Cheyenne VAMC campus. This will include new buildings that were constructed since the previous study as well as assessing electrical panels and equipment that were part of the previous study.

All buildings are surveyed and included in report. The survey and analysis are divided by sub-systems. The sub-systems are as follows:

A. New CLC

B. Utility through all transformers

C. Clinical Addition

D. Ambulatory Care included MRI Emergency Power

E. Bldg. 1 A

F. Bldg. 1 B

G. RRTP

H. Bldg. 45

I. Bldg. 1C

J. Boiler Plant and associated buildings

K. Outbuildings 4,5,6,7,8, etc. includes MRI normal power

For each of these sub-systems the following sections are provided:

1. One Line Drawing

2. Short Circuit Calculations – Momentary, Interrupting, Ground Fault

3. Equipment Duty

4. Voltage Drop

5. Arc Flash Hazard Calculations

6. Coordination TCC Plots

7. Settings for best coordination

8. Labels

9. Equipment condition and grades

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10. Data Base List

11. Comments are recommendations

3. General

3.1. Electrical coordination and arc-flash study in strict compliance with NFPA 70E - Standard for Electrical Safety in the Workplace, 2012 edition; and IEEE 242-2001 - Recommended

Practice for Protection and Coordination of Industrial and Commercial Power Systems.

The study used the most recent NFPA and IEEE Standards which are both 2018.

3.2. The Contractor shall conduct an entrance briefing with the Chief Engineer and Engineering staff upon arrival at the Cheyenne VAMC. The Contractor shall use this meeting to introduce their team and discuss the procedures for obtaining the necessary drawings and field information. At the completion of the site survey, the Contractor shall again conduct a short briefing with the Chief Engineer and staff to discuss any major problems or life-threatening issues if any are discovered during the survey.

Entrance briefing on September 23, 2019 – minutes provided and exit briefing at final

3.3. This electrical system study shall be conducted using EasyPower (minimum version 10.2.)

or equivalent electrical system modeling software. The Cheyenne VAMC has a current

EasyPower model that can be utilized as basis for the study. During the study the model must be updated and corrected wherever errors are found. The Contractor shall provide to the

Cheyenne VAMC a licensed copy (with one user station) of the same software used by the

Contractor to produce the report (EasyPower or approved equal); a five-year software update and support contract; and on-site training for eight (8) facility personnel. A copy of the final software model used to supply the study shall be turned over to the Cheyenne VAMC for the facility’s use and modification to capture any future facility work.

Study conducted using Easy Power 10.3

Easy Power Version 10.3 provided to VA with five-year license.

Training for 8 provided by Easy Power week of Feb. 24.

3.4. This electrical system study shall include testing of ground resistance for the entire facility in accordance with VHA Directive 1028 - Electrical Power Distribution Systems, dated July 25, 2014.

See section 7.3 of this document that defines ground resistance review.

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4. Qualifications

4.1. The short-circuit, protective device coordination, and arc-flash hazard analysis studies shall be conducted under the supervision and approval of a Registered Professional Electrical

Engineer skilled in performing and interpreting the power system studies.

Studied conducted by Registered Professional Electrical Engineers at Valhalla Engineering who are skilled in performing and interpreting the power system studies.

5. Integrated Baseline Review (IBR)

5.1. Upon completion of the study (30 to 60 days), the Contractor will conduct an Integrated

Baseline Review (IBR) meeting at the Cheyenne VAMC Engineering staff. At this meeting, the

Cheyenne VAMC mitigation strategy will be incorporated into a Risk Management Plan identifying the Cheyenne VAMC plan for correction of the deficiencies identified in the study.

The IBR is intended to allow the lead Engineer of the Contractor’s team the opportunity to provide the Owners (i.e., Chief Engineer, Cheyenne VAMC facility personnel) a mutual understanding of the risks inherent with deficiencies found and the potential consequences if such deficiencies are not corrected. In short, the Contractor Engineer should review the findings of the study with VAMC staff and explain inherent risks and respond to any questions regarding the study. Properly conducted, this IBR should foster the development of the Risk

Management Plan and garner support for correction of critical deficiencies. At the conclusion of the IBR the Contractor Engineer shall obtain signatures from the Cheyenne VAMC Chief

Engineer indicating they have received the study and have been apprised by the Contractor of the associated risks.

Review the findings of the study with VAMC staff and explain inherent risks and respond to any questions regarding the study.

Risk – Arc Flash – included in the training.

Risk – older panels have reduced reliability. A list of equipment grades from A to F included.

IBN part of final report.

6. Deliverables

6.1. A review copy shall be submitted to the Owner at 50%. This is to check progress and have a draft document to begin programming for future projects based on this study.

Review copy provided at 50%.

6.2. A final copy of the study, with details as described in Para 7. Results and

Recommendations included along with equipment grading.

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7. Scope of Work

7.1. The Contractor shall prepare a complete short circuit and coordination study including voltage drop calculations on the entire electrical systems (both normal power and emergency power) and at the emergency generators (for the emergency power system) and continue through to each branch circuit panelboard, motor control center, or motor control panel in each building. The study shall include a system on-line diagram, short circuit and ground fault analysis, protective coordination plots, voltage drop calculations and the following for each building: See individual sections.

7.2. One-Line Diagrams.

7.2.1. The one-line diagrams shall show the schematic wiring of the electrical distribution system for each building. Include all electrical equipment and wiring protected by the overcurrent devices.

7.2.2 Also show on the one-line diagrams the following specific information:

a. Calculated short-circuit values at each bus.

b. Breaker and fuse ratings.

c. Transformer kVA, voltage ratings, and wiring connections.

d. Voltage at each bus.

e. Identification of each bus.

f. Conduit material, feeder sizes, and lengths.

g. Generator kW and voltage ratings.

One lines Attachment Section 2 of each system.

7.3. Ground Resistance Analysis.

7.3.1. A concise qualitative description (not to exceed one (1) page of narrative) describing the overall condition of the facility ground resistance shall be provided. Any violations of NEC or other abnormalities (high ground resistance, damaged conductors or electrodes, harmonics, etc.) warranting further detailed study shall be highlighted. Analysis of the facility ground resistance shall be based upon:

a. Facility Ground Resistance Test reported, provided by Cheyenne VAMC Facility

Management Service (FMS).

b. Visual inspection of visible ground system components (made during site investigation). Include photographs in Appendices.

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c. Interviews with FMS maintenance and engineering staff.

d. Other data on ground system made available by FMS.

The Cheyenne VAMC electrical system is bonded together to a common overall ground system. Reported data shows overall resistance to ground as measured by the stakeless method showed 3.1 ohm. Code requires values below 10 ohm and 5 ohms is preferred. This complies.

Inspection of ground connection as observed during walk through inspection found ground connections in good condition.

7.4. Short Circuit Study.

7.4.1. Systematically calculate the fault impedance to determine the available short circuit and ground fault currents at each bus. Incorporate the motor contribution in determining the momentary and interrupting ratings of the protective devices. Motors less than 25-hp may be grouped together. See attachment Section 2 of each system.

7.4.2. Use actual conductor impedances if known. If unknown, use typical conductor impedances based on IEEE Standard 141-1993 - IEEE Recommended Practice for Electrical

Power Distribution for Industrial Plants.

Actual impedances are used. These are available from field work, electrical testing, and previous data collection.

7.4.3. Transformer design impedances shall be used when test impedances are not available.

Actual impedances are used. These are available from field work, electrical testing, and previous data collection.

7.4.4. Provide the following:

a. Calculation methods and assumptions.

IEEE 1584-2018 Guide for Performing Arc Flash Hazard Calculations, a revision of the original publication in 2002. The arc flash hazard calculations are dependent upon equipment voltage, bolted fault current, arc time, electrode gap, electrode configuration, and enclosure size.

b. Selected base per unit quantities. See attachment Section 10 of each system.

c. One-line diagram of the system being evaluated. See attachment Section 2 of each system.

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d. Source impedance data, including electric utility system and motor fault contribution characteristics. See attachment Section 2 and 10 of each system.

e. Tabulations of calculated quantities. See attachment Section 2 of each system.

f. Results, conclusions, and recommendations. See attachment Section 11 of each system.

7.4.5. Calculate short-circuit momentary and interrupting duties for a three-phase bolted fault at each:

a. Electric utility’s supply termination point.

b. Incoming switchgear.

c. Unit substation primary and secondary terminals.

d. Low voltage switchgear.

e. Motor control centers.

f. Standby generators and automatic transfer switches.

g. Branch circuit panelboards.

h. Machine control panels.

i. Bus ducts.

j. Other significant locations throughout the system.

Utility system

Feeder HILL (Preferred Source)

Isym (3-ph) = 2155 A X/R=3.43

Isym (1-ph) = 1257 A X/R=3.29

Feeder Crow (Alternate)

Isym (3-ph) = 2631 A X/R=1.38

Isym (1-ph) = 1487 A X/R=1.89

See attachment Section 2 of each system.

7.4.6. For grounded systems, provide a bolted line-to-ground fault current study for areas as defined for the three-phase bolted fault short-circuit study.

Report

The entire system is a grounded system and includes bolted line-to-ground as well as bolted three phase faults.

7.4.7. Protective Device Evaluation:

a. Evaluate equipment and protective devices and compare to short circuit ratings.

b. Adequacy of switchgear, motor control centers, and panelboard bus bars to withstand short-circuit stresses.

c. Notify Owner in writing, of existing, circuit protective devices improperly rated for the calculated available fault current.

Evaluation Section 3, 9, 10, 11 of each system.

Equipment Duty is specifically covered in section 3

7.5. Arc-Flash Hazard Analysis.

7.5.1. The arc-flash hazard analysis shall be performed according to IEE Standard 1584-2018 -

IEEE Guide for Performing Arc-Flash Hazard Calculations, equations that are presented in

NFPA70E-2012, Annex D.

Study and calculations based on the IEEE 1584-2018 Guide for Performing Arc Flash Hazard

Calculations, a revision of the original publication in 2002. The arc flash hazard calculations are dependent upon equipment voltage, bolted fault current, arc time, electrode gap, electrode configuration, and enclosure size.

7.5.2. The flash protection boundary and the incident energy shall be calculated at all equipment locations identified in the previous study (2014) as well as equipment placed into service since the previous study.

See attachment Section 5 of each system.

7.5.3. The arc flash hazard analysis shall include all significant locations in 480-volt and 208-volt systems fed from transformers equal to or greater than 125kVA where work could be performed on energized parts.

The new 2018 standard now includes transformers less than 125kVA and these are included in the results and arc flash labels.

7.5.4. Safe working distances shall be based upon the calculated arc flash boundary considering an incident energy of 1.2 cal/cm2.

See attachment Section 5 of each system.

Report

7.5.5. When appropriate, the short circuit calculations and the clearing times of the phase overcurrent devices will be retrieved from the short circuit and coordination study model.

Ground overcurrent relays should not be taken into consideration when determining the clearing time when performing incident energy calculations.

Provided in tables.

7.5.6. The short circuit calculations and the corresponding incident energy calculations for multiple system scenarios must be compared and the greatest incident energy must be uniquely reported for each equipment location. Calculations must be performed to represent the maximum and minimum contributions of fault current magnitude for all normal and emergency operating conditions. The minimum calculation will assume that the utility contribution is at a minimum and will assume a minimum motor contribution (all motors off).

Conversely, the maximum calculation will assume a maximum contribution from the utility and will assume the maximum amount of motors to bet operating. Calculations shall take into consideration the parallel operation of synchronous generators with the electric utility, where applicable

See attachment Section 5 of each system. Includes multiple scenarios specifically under emergency generator operation and normal operation.

7.5.7. The incident energy calculations must consider the accumulation of energy over time when performing arc-flash calculations on buses with multiple sources. Iterative calculations must consider the changing current contributions, as the sources are interrupted or decremented with time. Fault contribution from motors and generators should be decremented as follows:

a. Fault contribution from induction motors should not be considered beyond 3 to 5 cycles.

b. Fault contribution from synchronous motors and generators should be decayed to match the actual decrement of each as closely as possible (e.g., contributions from permanent magnet generators will typically decay from 10 per unit to 3 per unit after 10 cycles.

Model includes momentary, interrupting and continuous current data. Motors and generators are modeled to include contributions.

7.5.8. For each equipment location with a separately enclosed main device (where there is adequate separation between the line side terminals of the main protective device and the

Report work location), calculations for incident energy and flash protection boundary shall include both the line and load side of the main breaker.

Calculations performed for both. However, per NFPA 70E the arc flash is for the calculation that does not include main breakers in panels since the conductors feeding the main breakers are exposed when panel cover removed and there is a potential for an arc flash before the main breaker.

7.5.9. When performing incident energy calculations on the line side of a main breaker (as required above), the line side and load side contributions must be included in the fault calculation.

This is part of the Easy Power model.

7.5.10. Miscoordination should be checked amongst all devices within the branch containing the immediate protective device upstream of the calculation location and the calculation should utilize the fastest device to compute the incident energy for the corresponding location.

The current system consists of molded case circuit breakers without adjustable trips except at the building entry. Where adjustable trip units are available, they will be set to coordinate with downstream breakers. However, where multiple molded case breakers without adjustable trips are in series there is no coordination possible. Note that the main switchgear breakers on the medium voltage switchgear must be set to not trip on inrush from multiple transformers and this puts it outside the reach of any short circuit current beyond the transformers. These coordinate but do not limit fault current at the secondary terminals of the transformers. Fuses are included at transformer primary feeds, but these also must be sized larger than inrush. As a result, the transformers are not fully protected for faults at the secondary terminals. This also causes high arc fault levels at secondary transformer terminals and the first downstream panels and breakers. Future projects should consider digital relays for transformer protection.

7.5.11. Arc-flash calculations shall be based on actual overcurrent protective device clearing time. Maximum clearing time will be capped at 2 seconds based on IEEE Standard 1584-2018 section B.1.2. Where it is not physically possible to move outside of the flash protection boundary in less than 2 seconds during an arc-flash event, a maximum clearing time based on the specific location shall be utilized.

Model has option for 2-second limit. All locations have good access and can include the 2 second limit.

7.6. Arc Flash Labeling Section 8 of each system.

7.6.1. Arc flash warning labels in accordance with NFPA 70 (NEC) and NFPA 70E. Labels shall be

4-inch by 6-inch (nominal) printed on industrial quality, adhesive backed vinyl. “Danger” labels

Report shall have pre-printed headers in red; “Warning” labels shall have pre-printed headers in orange. Electrical equipment shall be labeled IAW NFPA 70, Article 110.16 and NFPA70E, Article 130.5 (C). The arc-flash hazard analysis to determine the arc-flash protection boundary for each label shall be calculated IAW NFPA 70E Paragraph 130.5 (A). For each device for which a hazardous analysis is conducted, the equipment shall be field marked with a label containing the available incident energy or required level of PPE.

7.6.2. In addition to the requirements of NFPA 70 and 70E, each customized label containing specific available incident energy or required level of PPE and shall identify the corresponding piece of electrical equipment, by panelboard or device identifier and building number. The identification shall be in a manner understood by Cheyenne VAMC facility personnel who will be applying the labels to the respective devices. Generic labels do not require equipment and building identifiers.

7.6.3. Arc-flash labels shall be provided in the following manner and all labels shall be based on recommended overcurrent device settings:

a. For each applicable 600-volt, 480-volt, and 208-volt panelboard, one arc-flash label shall be provided.

b. For each low-voltage switchboard, one arc-flash label shall be provided.

c. For each switchgear, one arc-flash label shall be provided.

d. For each switchgear, one arc-flash label shall be provided.

e. For medium voltage switches one arc-flash label shall be provided.

f. For each machine control panel, one arc-flash label shall be provided.

g. For each bus duct plug, one arc flash label shall be provided.

Labels - Section 8 of each system.

7.7. Protective Device Coordination Study

7.7.1. Prepare the coordination curves to determine the required settings of protective devices to ensure selective coordination. Graphically illustrate (using logarithmic scale) that adequate time separation exists between series devices, including the utility company upstream device.

Plot the specific Time Current Characteristics (TCC) of each device in the electrical system as follows:

a. Provide TCC curve down to the last branch-circuit panelboard (regardless the protective device is an adjustable or fixed device) in the three-branches of the

Essential Electrical System (EES).

b. Provide TCC curve down to the last adjustable device (stop after the first fixed device) in the Normal System but at the minimum two-level curves from each of the building Service Entrance switchgear/switchboard shall be provided.

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Attachments Section 6 of each system.

7.7.2. The following specific information shall also be shown on the coordination curves at each level of power distribution system:

a. Device identification (including manufacturer, catalog number, and device curve number and ID).

b. Voltage and current ratio for curves.

c. Three-phase and single-phase ANSI damage points for each transformer.

d. No damage, melting, and clearing curves for fuses.

e. Cable damage curves.

f. Transformer inrush points.

g. Maximum short circuit cutoff point.

h. Excerpts from one-line diagram reflecting the protective devices modeled on each curve. This excerpt may be inserted onto a corner (typically top right-hand) of the curve print out or may be on the preceding facing page for ease of reference.

i. Provide explanation, analysis, and recommendation to achieve better coordination.

j. The analysis for recommended curve of a device (either adjustments to the existing device or a recommended replacement device) shall be put right after the existing curve in the report for comparison.

Attachments Section 6 and 7 of each system.

7.7.3. Develop a table to summarize the settings selected for the protective devices. Include all medium voltage devices in the table, as well as all low voltage devices which require modification, showing the following data:

a. Device identification.

b. Relay CT ratios, tap, time dial, and instantaneous pickup.

c. Circuit breaker sensor rating, long time, short time, and instantaneous settings, and time bands.

d. Fuse rating and type.

e. Ground fault pickup and time delay.

Section 7 of each system.

7.8. Voltage Drop Calculations

7.8.1. Provide voltage drop calculations for all three-phase branch and feeder circuits. Show calculated voltages at each bus and voltage drops on each feeder.

7.8.2. Calculations shall be based on the maximum values of kVA, kW, kvar, power factor, and amperes for each power circuit.

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a. For branch circuit level, use 80% of nameplate rating.

b. For incoming service and distribution level, use 50% of the nameplate rating or actual maximum peak demand load collected in the field if it is available.

7.8.3. Provide tabular information showing the sizes of all cables, transformers and other circuit data.

7.8.4. Provide a system one-line diagram which clearly identifies individual equipment busses, bus numbers, cable and bus connections and other circuit information.

7.8.5. Provide a separate section or tables which provide an evaluation of the calculated voltage drops with recommendations for improvements where voltage drops exceed the allowable NEC limits.

Attachments Section 4 of each system.

7.9. Emergency Power System Analysis

7.9.1. First, a narrative describing the existing emergency power systems shall be provided, to include a description of each emergency generator, physical location, size (kW and ampacity), voltage, configuration (phase, wire), circuit number, age, and overall condition. A summary of the average loading on each generator (based on data provided by FMS staff) shall be provided and then compared to projected future loads. The Contractor Engineer shall develop load projections from discussing forecast projects and growth with FMS Engineering staff). Finally, the Contractor shall provide a qualitative narrative on the suitability of the existing generators to meet projected future loads. If the existing emergency power system, including generators, is not adequate to meet either current or future demands, the Contractor shall provide recommendations in the study.

The current loading of emergency generators show they are at approximately 50% capacity.

This is sufficient for current and additional loading. Generator 2 has load of 166 KVA with a capacity of 437 KVA, Generator 3 has load of 231 KVA with a capacity of 480 KVA and

Generator 4 has load of 248 KVA with a capacity of 344 KVA. These have been de-rated due to altitude. The new generator for the new CLC has not been accepted but will be more than sufficient for current and future load.

7.10. Analysis and Recommendations

7.10.1. For all electrical equipment, determine if adequate code clearances exist. Note cases by location and specific equipment that do not include adequate code clearances and provide a cost estimate to resolve the problems. Provide information in table format.

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Clearances for all electrical equipment. On site review found only one instance where clearances did not meet code. This is a panel in the crawl space under building 1. A summery of the site visit is included in the section on overall condition of the electrical systems. There are some cases where mobile equipment is blocking access but these items can be moved out of the way when working on the panels.

7.10.2. Determine if ground fault protection exists where required by NFPA 70 Articles 215 and

517. Note all cases where this condition exists and provide cost estimates to correct. Provide information in table format.

Ground fault protection is not provided. NEC is not retro-active. Future projects should include ground fault protection per most recent NEC.

7.10.3. For all automatic transfer switches, determine if the correct 3-pole or 4-pole switches are used. Where ground fault protection is used on the normal feed to the switch, determine if the switch is correctly wired. Note all cases where this condition exists and provide cost estimates to correct. Provide information in table format.

Both 3 pole and 4 pole ATSs are used. However, each generator uses the same type except when downstream on a separately derived (transformer). There are no code deficiencies associated with the number of poles. It is important in any new work to keep consistent with the number of poles on the ATS and not to mix 3 pole ATSs with 4 pole ATSs on the same generator.

ATSs Poles Base kV Generator

ATS TS1EC 3 0.208 2

ATS

TS1EE2

3 0.208 2

ATS-32ES1 3 0.208 2

ATS-

TS1EE1

TS1ES1

ATS EHB3 3 0.48 3

ATS-BP 4 0.208 3 This is OK since separately derived

ATS-CH21 3 0.48 3

ATS-

CHB11

3 0.48 3

ATS-EHB2 4 0.48 3

ATS-EHB1 3 0.48 3

ATS-LH11 3 0.48 3

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ATS-

DPCHC

4 0.48 4

DPEHC

DPLHC

ATS-RRTP 4 0.48 4

ATS-SERV 4 0.208 4 This is OK since separately derived

ATS-CHB1 4 0.48 5

ATS-EHB 4 0.48 5

ATS-LHB1 4 0.48 5

7.10.4. Note any use of cable limiters and provide recommendations to avoid any single phasing conditions. Note all cases where this condition exists and provide cost estimates to correct. Provide information in table format.

There are no cable limiters on the system.

7.10.5. On the medium voltage switchgear, where undervoltage relays (27) are used, determine whether all three phases are monitored or if only two phases are monitored. For those locations where only two phases are monitored, provide a cost estimate for providing adequate protection for all three phases.

No undervoltage relays (27) on main breakers.

7.10.6. Analyze the short-circuit calculations and highlight any equipment that is determined to be underrated. Provide recommendations to effectively protect the underrated equipment.

Misapplied equipment. Section 3 of each system.

7.10.7. After developing the coordination curves, highlight areas lacking coordination. Present a technical evaluation with a discussion of the logical compromises for best coordination.

7.10.8. Assess the equipment condition using grading method in term of A, B, C, D and F.

a. Grade A - Like New Condition; majority of useful lifespan remains. “Excellent”

b. Grade B - Good Condition; over half of useful lifespan remains. “Good”

c. Grade C - Average Condition; less than half of useful lifespan remains. “Average” or

“Fair” or C+ "Above Average"

d. Grade C - Workable Condition; may be past assigned useful life, but still working

“Keep an eye on it”

e. Grade D - Poor Condition; past assigned useful life, but failure is not critical. “Poor” or “Problematic”

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f. Grade F - Critical Condition; needs immediate attention. “Failing” or “Critical”

Grade all equipment. Section 9 of each system and overall list of electrical equipment with grades. Also, separate document provided.

7.11. Protective Device Settings

7.11.1. For all adjustable and fixed protective devices, provide tables to show existing settings and new settings where changes are recommended for proper protection.

7.11.2. If adjustments will not provide adequate protection, provide recommendations to update or replace the existing underrated equipment and include cost estimates to accomplish the necessary corrections.

7.11.3. Provide table in Excel format to show ONLY the devices that require settings in need of adjustment. See Section 6 of each system for adjustments. Overall, no adjustments needed at this time. New coordination should be included as part of new Clinical Addition project.