26 05 73 - Power System Study and Testing.pdf

26 05 73 – POWER SYSTEM STUDY AND TESTING

Herbert, Rowland & Grubic, Inc. 26 05 73-1 005153.0436

SECTION 26 05 73 - POWER SYSTEM STUDY AND TESTING

PART 1 - GENERAL

1.1 SUMMARY

A. This section includes the requirements for performing a power system study.

B. This section includes general requirements for performing a power system study including short circuit analysis, coordination study, arc-flash hazard evaluation and harmonics analysis, and testing of the new portions of the electrical power distribution system. The studies shall include all portions of the electrical distribution system from the connection into the distribution switchgear down to and including the smallest adjustable trip circuit breaker in the distribution system as shown on the Contract Drawings for the plant upgrade.

C. The Contractor shall obtain the services of a single independent Power System Analysis Firm (PSA) who shall be responsible for preparing project specific studies and field testing for all components of the power study as specified herein. The PSA shall be regularly engaged in the business of performing short circuit analysis, coordination studies, and harmonics analysis and testing for medium voltage and low voltage power distribution systems.

1.2 RELATED SECTIONS

A. All sections of Division 1, General Requirements.

B. Division 26.

1.3 QUALITY ASSURANCE

A. References - Materials and installation shall be in accordance with the latest revisions of the following codes, standards and specifications, except where more stringent requirements have been specified herein:

1. Local Building Codes.

2. National Electrical Code – NEC.

3. Underwriters Laboratories, Inc. – UL.

4. Institute of Electrical and Electronic Engineers – IEEE.

5. Insulated Cable Engineers Association – ICEA.

6. American National Standard Institute – ANSI.

7. International Electrical Testing Assoc., Inc. – NETA.

B. Power System Analysis Firm:

1. The PSA shall demonstrate the requisite resources of in-house staff, facilities and test equipment to complete the project in the schedule specified. These resources shall include personnel who are direct payroll employees of the PSA to perform engineering and field testing of the related power distribution systems.

2. The PSA shall assign a specific person to serve as the Project Manager for this project. The Project Manager shall be a direct employee of the PSA and shall be

Herbert, Rowland & Grubic, Inc. 26 05 73-2 005153.0436 a licensed professional engineer in the State of Pennsylvania. The Project Manager shall have a minimum of 15 years’ experience in power systems evaluations. Should it become necessary to replace him, the Contractor shall submit to the Engineer the credentials of the person assigned as a replacement.

1.4 SUBMITTALS

A. Submittals shall be submitted in accordance with the provisions set forth in 01 33 00 Submittals and 26 05 00 – Electrical - General.

B. Submit a qualifications package for the proposed PSA for this project. The qualifications package shall include the following information which shall be organized and formatted as follows:

1. Company Background - Provide a brief company overview detailing PSA’s experience, capabilities, and available resources. Description of available resources shall include labor categories, staffing, and testing equipment.

2. Experience in Power Distribution System Evaluations - Provide a list of recent projects (last five years from the bid opening date of this contract) involving short circuit, coordination, arc-flash analysis and harmonics studies and testing that the has successfully performed.

3. Facilities and Equipment – List type and edition of power system analysis software and testing equipment to be used for this project.

C. Submittal Coordination with Equipment Manufacturers - The PSA shall obtain specific submittal information pertaining to proposed power distribution equipment from the Owner and Contractor for the existing and proposed equipment manufacturers. This shall include manufacturer’s catalog information, equipment ratings, and circuit breaker curves. Reports submitted without the information on existing and proposed power distribution equipment will be rejected. As a minimum, PSA shall obtain equipment information on the following equipment as applicable:

1. Utility service entrance information for normal source and emergency source feeders.

2. Pad-mounted transformers/unit substation.

3. Dry-type transformers.

4. Panelboards and circuit protective devices.

5. Uninterruptable power supplies.

6. Variable frequency drives (VFDs).

7. Field-mounted control panels (UL 508A compliance).

D. Power System Study Reports:

1. The PSA shall submit power system study reports that shall include the coordination study, short circuit analysis, harmonics analysis, harmonics measurements, and final summary and recommendations. Three separate and distinct submittals as specified herein.

2. Preliminary Power System Study Report:

a. The preliminary power system study report shall be based on the following information:

1) Preliminary submittal information for:

a) Cables and conductors.

b) Transformers.

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c) Panelboards.

d) Overcurrent protective devices.

e) Surge suppression equipment.

f) VFDs.

g) Field-mounted three phase control panels and components.

2) Utility information.

3) Information from the Contract Drawings.

4) Information from the equipment specifications.

5) Information provided by the Owner.

b. The preliminary power system study report shall be submitted prior to, or with the individual equipment submittals as specified in the individual equipment specifications. The report information will be used by the Engineer to review the equipment submittals for overall approval of the shop drawings. Submission of individual equipment submittals without the preliminary report will not be reviewed and will be returned to the Contractor.

c. It is the responsibility of the Contractor to forward the proposed electrical equipment submittal information to the PSA prior to submission of the submittals to the Engineer for review.

d. The preliminary report shall consist of the following:

1) List of proposed power distribution equipment to be provided, with corresponding technical information for equipment pertaining to the study.

2) Short circuit study evaluation for the proposed power distribution equipment. Provide recommendations for utilization of the proposed equipment based on the adequacy of the short circuit withstand ratings, bus bracing, and overcurrent protective device ratings. Provide recommendations for mitigating problems with such issues.

3) Harmonics analysis for the proposed VFD units. Identify the harmonic voltage/current distortion levels at each point in the system and provide recommendations for mitigating any problems that may arise based on the distortion levels.

4) An Engineer’s review code of “Approved” or “Approved As Corrected” will allow the PSA to proceed with the next report submission. The Engineer reserves the right to request modifications to relay and circuit breaker settings based on operational preferences. Such requests shall be incorporated into the next report submission.

3. Pre-Final Power System Study Report – Report shall consist of the following:

a. All information contained in the preliminary report, with

Engineer’s/Owner’s comments addressed and incorporated.

b. Address all Engineer’s/Owner’s comments from previous report. Any comments from the electrical utility on service equipment relay settings and circuit breaker settings shall also be addressed. Re-evaluate the model to address any comments and provide revised coordination settings for the Contractor to use to make final adjustments to the electrical equipment settings.

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c. Provide coordination study with recommended relay settings, adjustable trip circuit breaker settings, and fuse ratings for the electrical distribution system.

d. An Engineer’s review code of “Approved” or “Approved As Corrected” will allow the Contractor to proceed with making the settings on the circuit protective devices.

4. Final Power System Study Report – Report shall consist of the following:

a. All information contained in the pre-final report, with

Engineer’s/Owner’s comments addressed and incorporated.

b. Results of field harmonics measurements and testing.

c. Final summary and recommendations for power distribution system and

VFDs.

d. Report shall be submitted upon completion of the harmonics measurements and testing. Engineer’s comments on final report shall be addressed, and the final report resubmitted, until the final report is provided with an “Approved” review code by the Engineer.

5. More detailed requirements for report content are described in Part 2 of this specification.

E. Electronic Copies - Submit two copies of the electronic files for the final power system study for future updating and reference by the Owner. Files shall be submitted compact disc in MS Word format.

F. Arc-Flash Hazard Labels - The PSA shall furnish and install warning labels for all electrical equipment associated with this project.

PART 2 - PRODUCTS

2.1 GENERAL

A. The power system study shall be provided to evaluate the power distribution system for equipment interrupting capacity, system coordination, system protection, and proper operation within the system limits. The power system study shall include the following components:

1. Short circuit analysis.

2. Coordination study.

3. Arc flash hazard analysis.

4. Harmonics analysis.

5. Results of harmonics measurements.

6. Final summary and recommendations.

B. The power system study shall be performed with the aid of a digital computer program using SKM software specifically designed for that purpose. No substitutions will be allowed. Computer programs shall follow the latest applicable IEEE and ANSI standards.

C. Power Distribution System Information and Data:

1. The PSA shall obtain utility source information from the power utility.

2. Motor contributions shall be based on motor loads indicated on the Contract

Drawings and in the specifications.

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3. Cable and conductor impedances may be obtained from standard libraries for equivalent conductors and cables.

2.2 SHORT CIRCUIT ANALYSIS AND COORDINATION STUDY

A. The short circuit analysis and coordination study shall analyze short circuit occurrence during normal conditions when both utility feeders are available, and when one utility feeder is out of service and the generators are operational. The Short Circuit Analysis and Coordination Studies shall be performed in accordance with ANSI/IEEE C37.10, ANSI/IEEE C37.13, IEEE Standard 141, IEEE Standard 242, IEEE Standard 399, and NETA Acceptance Testing Specifications 6.1, Short Circuit Studies, and 6.2, Coordination Studies.

B. Short Circuit Analysis Parameters:

1. The short circuit analysis shall be performed to determine the available (worst case) fault level at critical buses on the distribution system. The basis for the analysis shall be that a “three-phase” bolted fault can occur anytime on any bus in the system.

2. Provide calculation methods and assumptions, base per unit quantities selected, one-line diagrams, source impedance data including power company system characteristics as applicable, typical calculations, tabulations of calculated quantities and results.

3. Calculate short-circuit interrupting and momentary (where applicable) duties for an assumed 3-phase bolted fault at each supply switchgear lineup, motor control center, power panelboard, lighting panelboard, and other significant overcurrent protective device locations throughout the system.

4. Provide a ground fault current study for the same system areas, including the associated zero sequence impedance data. Include in tabulations fault impedance, X to R ratios, asymmetry factors, motor fault contribution, short circuit kVA, and symmetrical and asymmetrical fault currents.

C. Coordination Study Parameters:

1. Provide a complete short circuit and system protection coordination study of the electrical distribution system with manufacturer’s curves of each protective device indicated on common drawings, to verify proper selectivity and protection for all components of the system obtained. Include all calculations, selected equipment, devices, and recommended settings. The study shall encompass all existing and new devices from the utility connection and the existing on-site generator to the motor control center, panelboards, and 480 V field-mounted protective devices, including those located in free-standing control panels.

2. Provide time-current curves graphically indicating the coordination proposed for the system. Curves shall be provided on full size, log-log forms. Each curve sheet shall be provided with an appropriate title, one line diagram, and identified components or legend. The study shall include coordination curves showing the proposed settings of protective devices required to assure selective coordination. Specific time-current characteristics of each protective device shall be plotted in such a manner that all upstream devices, including utility protective devices, will be clearly depicted on a full-size single log paper sheet.

Herbert, Rowland & Grubic, Inc. 26 05 73-6 005153.0436

3. Provide a detailed description of each protective device identifying its type, function, manufacturer, and time-current characteristics. Provide recommended device tap, time dial, pick-up, instantaneous, and time delay settings in a table format.

4. The curve sheets shall include the utility company relay and fuse characteristics (as applicable), low voltage equipment circuit breaker trip device characteristics, pertinent transformer characteristics, motor and generator characteristics.

Devices shall be shown down to the largest branch and feeder circuit breaker in each motor control center and panelboard.

5. Provide adjustable settings for ground fault protective devices. Include manufacturing tolerance and damage bands in plotted fuse characteristics.

Transformer full load currents, magnetizing inrush, ANSI transformer withstand ratings, and significant symmetrical fault currents shall be included on the curves. Terminate device characteristic curves at a point reflecting the maximum symmetrical fault current to which the device is exposed.

2.3 HARMONICS ANALYSIS

A. The PSA shall evaluate the estimated harmonic distortion levels for the power distribution system. Simulate via computer modeling the power distribution system with harmonic generating devices including VFDs, uninterruptible power supplies (UPS), and other significant harmonic generating equipment.

B. Perform frequency scans (2nd to 50th harmonics) to determine the frequency response characteristics looking at each of the selected busses described in Article 3.4 of this specification.

C. Provide computer simulation results including a spectrum of individual harmonic levels, bus voltage distortion levels, and current distortion levels. The results shall be evaluated based on the recommended limits outlined in IEEE Standard 519-1992.

D. Harmonics analysis shall be performed using recognized harmonic analysis computer programs. The VFD and UPS equipment parameters and specifications proposed for this project shall be input to the computer programs.

E. The final simulations shall be used to develop solutions to any potential harmonic problems. The PSA shall provide recommendations for solutions to eliminate any problem associated with harmonics to bring the system into compliance with the harmonic distortion limits recommended in IEEE 519-1992.

F. The final simulation results shall be compared to the field measurements taken during operation of the equipment as described in Article 3.4 of this specification, with corresponding final summary and recommendations included in the final report.

2.4 REPORT

A. A comprehensive report shall be prepared to document each component of the power system study. The report shall be clearly organized and provided with tab dividers to separate logical sections. The report shall include the following information as a minimum:

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1. General Description - Provide a general description outlining the purpose of the report. The general description shall include a basis and scope for the limits of the study.

2. Short Circuit Analysis:

a. Describe the parameters which have an impact on the analysis in explicit detail.

b. Compare the manufacturer’s published interrupting, withstand and bus bracing ratings with the calculated available fault levels.

c. Summarize any system deficiencies or shortcomings with the interrupting capability of the proposed distribution equipment.

d. Provide recommendations and solutions for correcting any deficiencies.

3. Coordination Study:

a. The study shall include performing time-current analysis of each protective device.

b. The PSA shall provide recommendations for setting and adjusting the protective relay and circuit breaker settings and parameters to assure proper equipment and personnel protection.

c. Provide conclusions based on the compiled information, and recommendations for modifications to equipment or systems to correct any deficiencies.

4. Arc-Flash Hazard Analysis:

a. The report shall include an Incident Energy Study performed in accordance with the IEEE 1584-2004a, ”IEEE Guide for Performing Arc Flash Hazard Calculations” as referenced in NFPA 70E, “Standard for Electrical Safety in the Workplace”, latest Revision, in order to quantify the hazard for selection of personal protective equipment (PPE). Tables that assume fault current levels and clearing time for proper PPE selection are not acceptable.

b. Report shall include incident energy level (calories/cm2) for each equipment location and recommended PPE.

c. The PSA shall optimize the results of the study as it relates to safety and reliable electrical system operation (e.g. overcurrent device settings, working distances, current limiting devices). This includes mitigation, where possible, of incident energy levels that exceed 40 calories/cm2.

5. Harmonics Analysis:

a. The study shall include harmonic distortion analysis for voltage and current predicated at the VFD input terminations, UPS input terminations and upstream equipment busses as specified herein.

b. Identify magnitude of harmonic voltage and current distortion including individual harmonics up to and including the 50th, total harmonic distortion (THD) on the system, as well as de-rating factors affecting equipment.

c. Verify, via analysis that the maximum permissible harmonic distortion of the system complies with IEEE 519, ANSI/IEEE Standard 18, ANSI/IEEE Standard 398, and IEEE Standard 1036.

6. Final Summary and Recommendations - Provide a final summary of all findings, and final recommendations, based on field measurements taken, and analyses performed.

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7. Appendices:

a. Provide computer input and output databases used in the evaluations.

b. Provide one or more comprehensive one-line diagrams for the power distribution system. Components shall be specifically labeled with tags and values which correlate to referenced items noted in the studies.

c. Provide an equivalent impedance one-line diagram for the power distribution system. Components shall be specifically labeled with tags and impedance values which correlate to referenced items noted in the studies.

d. Provide field data for harmonic values obtained while conducting field measurement surveys.

e. Provide field data for power measurement values obtained while conducting field measurement surveys.

f. Provide an image sample of an arch flash label.

2.5 ARC-FLASH HAZARD LABELS

A. Based on the results of the incident energy study, the supplier shall produce and install warning labels (orange <40 cal/cm2) or danger label (red >40 cal/cm2) for each piece of equipment in accordance with ANSI Z535.4-2002. The label must be readable in both indoor and outdoor environments for at least three years and contain the following information:

1. Arc hazard boundary (inches).

2. Working distance (inches).

3. Arc flash incident energy at the working distance (calories/cm2).

4. PPE category and description including the glove rating.

5. Voltage rating of the equipment.

6. Limited approach distance (inches).

7. Restricted approach distance (inches).

8. Prohibited approach distance (inches).

9. Equipment/bus name.

10. Date prepared.

11. PSA name and address.

PART 3 - EXECUTION

3.1 GENERAL

A. Power distribution equipment shall not be energized prior to adjusting and setting all of the relay protective devices by the Contractor in accordance with approval of the pre-final power system study report.

B. Contractor shall furnish and install arc-flash warning labels on equipment.

3.2 DATA COLLECTION

A. Utility Information - Short-circuit currents or impedances available from the electric utility system supplying the existing and new power distribution system, and time-

Herbert, Rowland & Grubic, Inc. 26 05 73-9 005153.0436 current characteristics and the settings of the utility protective devices on the supply side of the feeders, as applicable, shall be requested from the electric utility by the PSA.

B. Equipment Submittals and Technical Information - The PSA shall obtain equipment submittal information and technical information for the power distribution equipment and VFDs proposed for the project.

3.3 FIELD CALIBRATION

A. The PSA shall supervise the performance of the on-site field adjustments by the Contractor for the protective relays, devices, and adjustable circuit breaker settings.

Contractor shall adjust the final settings in accordance with the final power system study report and as required for proper operation of the new electrical system.

B. The on-site field adjustments performed by the Contractor shall be supervised by a power systems technician who shall be present, on-site, as required to set and calibrate each power distribution unit. The Contractor shall coordinate the number of site trips required for the PSA with the sequencing of the installation and startup of the associated equipment. The technician shall be present on-site for a minimum of 16 hours (excluding travel time) for installation assistance, inspection, and certification of the installation.

3.4 HARMONICS MEASUREMENTS AND TESTING

A. Field measurements shall be performed in the presence of the Owner’s representative.

The PSA shall furnish all materials, labor, and equipment necessary to conduct field measurements. The PSA shall maintain a written record of all measurements, which includes date, test performed, personnel involved, devices tested, serial number and name of test equipment, and measurement results in the form of an analysis report described below:

1. The PSA shall perform on-site field services and data collection to obtain harmonic measurements (voltage and current harmonic levels) and power measurements (real power, kW and reactive power kVAR) for the distribution system. Measurements shall be taken at the following busses as a minimum:

a. Low voltage side of pad-mounted transformers.

b. 240V panelboards.

c. 480V VFDs (input terminal connections).

d. UPS line terminations.

2. The PSA shall note specific conditions at the time the measurements are taken, including motor status, motor speed, and loading levels. Snapshots of measurements shall be taken for VFDs rated 10 HP and larger. Power measurements shall be compared to values provided by the digital power meters and digital power monitors located on the equipment.

3. Harmonic measurements shall be taken for the worst case system configurations and load schemes. The PSA shall coordinate scheduling of the work with the Contractor in order to test the system with all equipment in operation. The Contractor shall make arrangements to schedule all monitoring work in order to not adversely affect the treatment plant testing.

4. Results of the harmonic field measurements shall include a spectrum of individual harmonic levels, voltage distortion levels and current distortion levels

Herbert, Rowland & Grubic, Inc. 26 05 73-10 005153.0436 at each of the selected buses. Provide tabulated results similar to IEEE-519, 1992, Appendix 4.9, Table 13.2 and Appendix 4.10, Table 13.3 and plotted results similar to IEEE-519, 1992, Appendix 4.8, Figure 9.1 and Figure 9.2. Results of power factor field measurements shall be tabulated.

5. Field measurements shall be collected using a power and harmonic analyzer similar to Fluke Model 434 or equal.

END OF SECTION