Section 26 05 73.doc

Modular Office Complex Building No. 365

2016005

SECTION 26 05 73

OVERCURRENT PROTECTIVE DEVICE COORDINATION STUDY

PART 1 - GENERAL

1.1 SUMMARY

A. This Section includes computer-based, fault-current and overcurrent protective device coordination studies. Protective devices shall be set based on results of the protective device coordination study.

1. Coordination of series-rated devices is permitted where indicated on Drawings.

1.2 REFERENCES

A. The publications listed below form a part of this Specification to the extent referenced. The publications listed below are referenced as the latest edition published as of the date of this document. The publications are referred to within the text by the basic designation only.

B. FAA Specifications and Standards

1. FAA Order 6950.2, Electrical Power Policy Implementation at National Airspace System Facilities.

2. FAA Order 6950.27, Short Circuit Analysis and Protective Device Coordination Study.

C. Institute of Electrical and Electronics Engineers (IEEE)

1. IEEE 1015, Recommended Practice for Applying Low-Voltage Circuit Breakers Used in Industrial and Commercial Power Systems.

2. IEEE 242, Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems.

3. IEEE 399, Recommended Practice for Power System Analysis.

4. IEEE 620, Guide for the Presentation of Therrmal Limit Curves for Squirrel Cage Induction Machines.

5. IEEE C37.13, Standard for Low-Voltage AC Power Circuit Breakers Used in Enclosures.

6. IEEE C37.46, Standard for High Voltage Expulsion and Current-Limiting Type Power Class Fuses and Fuse Disconnecting Switches.

7. IEEE C37.50, Standard for Switchgear--Low-Voltage AC Power Circuit Breakers Used in Enclosures--Test Procedures.

8. IEEE C57.12.00, Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers.

9. IEEE C57.96, Guide for Loading Dry-Type Distribution and Power Transformers.

D. Insulated Cable Engineers Association (ICEA)

1. ICEA P-32-382, Short-Circuit Characteristics of Insulated Cable.

2. ICEA P-45-482, Short-Circuit Performance of Metallic Shielding and Sheaths.

E. International Electrical Testing Agency (NETA)

1. NETA ATS, Acceptance Testing Specifications for Electric Power Distribution Equipment and Systems.

F. National Electrical Manufacturers Association (NEMA)

1. NEMA MG 1, Motors and Generators.

G. National Fire Protection Association (NFPA)

1. NFPA 70, National Electrical Code.

1.3 SUBMITTALS

A. Drawings: Power single line diagram with available short circuit currents indicated for each distribution system component.

B. Product Data: For computer software program to be used for studies.

C. Product Certificates: For coordination-study and fault-current-study computer software programs, certifying compliance with IEEE 399.

D. Qualification Data: For coordination-study specialist.

E. Other Action Submittals:

1. Coordination-study input data, including completed computer program input data sheets.

2. Study and Equipment Evaluation Reports.

3. Coordination-Study Report.

4. Setting Report.

5. Arc Flash Report and Labels

1.4 QUALITY ASSURANCE

A. Studies shall use computer programs that are distributed nationally and are in wide use. Software algorithms shall comply with requirements of standards and guides specified in this Section. Manual calculations are not acceptable. Comply with IEEE 399 for general study procedures. Comply with IEEE 242 for short-circuit and coordination time intervals. Short-circuit and coordination study shall comply with FAA Order 6950.2 and FAA Order 6950.27.

B. Coordination-Study Specialist Qualifications: Furnish services of electrical distribution equipment manufacturer or licensed Professional Engineer, by the state of New Jersey, to make a complete system short circuit and protective device electrical coordination study on 12,470 volt primary voltage system, and 480 and 208 volt secondary system. The entity shall be experienced in the application of computer software used for studies, having performed successful studies of similar magnitude on electrical distribution systems using similar devices.

C. Testing Agency Qualifications: Member Company of the International Electrical Testing Association.

D. Testing Agency's Field Supervisor: Person currently certified by the International Electrical Testing Association to supervise testing specified in Part 3.

PART 2 - PRODUCTS

2.1 COMPUTER SOFTWARE DEVELOPERS

A. Subject to compliance with requirements, provide computer software programs developed by SKM System Analysis, Incorporated.

2.2 COMPUTER SOFTWARE PROGRAM REQUIREMENTS

A. Comply with IEEE 399.

B. Analytical features of fault-current-study computer software program shall include "mandatory," "very desirable," and "desirable" features as listed in IEEE 399.

C. Computer software program shall be capable of plotting and diagramming time-current-characteristic curves as part of its output. Computer software program shall report device settings and ratings of all overcurrent protective devices and shall demonstrate selective coordination by computer-generated, time-current coordination plots.

1. Optional Features:

a. Arcing faults.

b. Simultaneous faults.

c. Explicit negative sequence.

d. Mutual coupling in zero sequence.

PART 3 - EXECUTION

3.1 EXAMINATION

A. Examine Project overcurrent protective device submittals for compliance with electrical distribution system coordination requirements and other conditions affecting performance.

1. Submission and approval of electrical short circuit and coordination studies are required prior to submittal of Shop Drawings of electrical distribution equipment. Submittal of electrical distribution equipment made prior to approval of Electrical Studies will be returned without approval.

2. The arc flash study can be completed after relevant equipment submittals have been assembled.

3.2 SHORT CIRCUIT CURRENT STUDY

A. Source impedance: As an infinite bus on primary side of utility transformer. Study electrical distribution system from normal power sources throughout electrical distribution system for project and use approved computer software program to calculate values. Include studies of system-switching configurations and alternate operations that could result in maximum fault conditions. Calculate momentary and interrupting duties on the basis of maximum available fault current. Use utility data where available. Calculations to verify interrupting ratings and overcurrent protection devices shall comply with the following:

1. Low-Voltage Circuit Breakers: IEEE 1015 and IEEE C37.50.

2. Low-Voltage Fuses: IEEE C37.46.

3. Circuit Breakers: IEEE C37.13.

B. Study Report:

1. Tabulation of input data including all short circuit sources and system impedances and electrical short circuit currents at each bus in system with contributions from connected busses. Comparison of interrupting and withstand ratings of electrical devices including circuit breakers, fuses, disconnect switches, transfer switches, starters and bus ducts, versus available fault current shall be included. Allowance shall be made for 20 percent growth in short circuit source contributions, for example, utility and motors.

a. Provide symmetrical three-phase bolted fault currents at 1 cycle (momentary), 5 cycles (interrupting) and steady-state (synchronous) for medium-voltage systems.

b. Provide symmetrical three-phase bolted fault currents at 1 cycle (momentary) for low-voltage systems.

c. Provide symmetrical line-to-ground bolted fault currents at 1 cycle (momentary) for solidly grounded multiple generator systems.

d. Calculations shall be completed in accordance with applicable ANSI and IEEE standards.

e. Calculations shall be completed for the worst case (maximum short circuit current) configuration of the electrical system. Wherever closed transition transfer is incorporated in the design, the contributions from both paralleled sources shall be included in the fault calculations. Tie circuit breakers shall be configured for the maximum utility and motor fault contribution.

C. Equipment Evaluation Report:

1. Prepare a report on the adequacy of overcurrent protective devices and conductors by comparing fault-current ratings of these devices with calculated fault-current momentary and interrupting duties.

3.3 COORDINATION STUDY

A. Gather and tabulate the following input data to support coordination study:

1. Product data for overcurrent protective devices specified in other Division 26 Sections and involved in overcurrent protective device coordination studies. Use equipment designation tags that are consistent with electrical distribution system diagrams, overcurrent protective device submittals, input and output data, and recommended device settings.

2. Impedance of utility service entrance.

3. Electrical distribution system diagram showing the load current that is the basis for sizing continuous ratings of circuits for cables and equipment.

4. Circuit breaker and fuse-current ratings and types.

5. Relays and associated power and current transformer ratings and ratios.

6. Transformer kilovolt amperes, primary and secondary voltages, connection type, impedance, and X/R ratios.

7. Generator kilovolt amperes, size, voltage, and source impedance.

8. Cables. Indicate conduit material, sizes of conductors, conductor insulation, and length.

9. Busway ampacity and impedance.

10. Motor horsepower and code letter designation according to NEMA MG 1.

11. Data sheets to supplement electrical distribution system diagram, cross-referenced with tag numbers on diagram:

a. Special load considerations, including starting inrush currents and frequent starting and stopping.

b. Magnetic inrush current overload capabilities of transformers.

c. Motor full-load current,locked rotor current, service factor, starting time, type of start, and thermal-damage curve.

d. Ratings, types, and settings of utility company's overcurrent protective devices.

e. Special overcurrent protective device settings or types stipulated by utility company.

f. Time-current-characteristic curves of devices indicated to be coordinated.

g. Manufacturer, frame size, interrupting rating in amperes rms symmetrical, ampere or current sensor rating, long-time adjustment range, short-time adjustment range, and instantaneous adjustment range for circuit breakers.

h. Manufacturer and type, ampere-tap adjustment range, time-delay adjustment range, instantaneous attachment adjustment range, and current transformer ratio for overcurrent relays.

i. Panelboards, switchboards, motor-control center ampacity, and interrupting rating in amperes rms symmetrical.

Perform coordination study and prepare a written report using the results of fault-current study and approved computer software program. Comply with IEEE 399. Comply with NFPA 70 for overcurrent protection of circuit elements and devices. Comply with IEEE 242 recommendations for fault currents and time intervals B. Transformer Primary Overcurrent Protective Devices:

1. Device shall not operate in response to the following:

a. Self-cooled, full-load current or forced-air-cooled, full-load current, whichever is specified for that transformer.

b. Permissible transformer overloads according to IEEE C57.96 if required by unusual loading or emergency conditions.

c. Device shall protect transformer according to IEEE C57.12.00, for fault currents.

C. Conductor Protection:

1. Protect cables against damage from fault currents according to ICEA P-32-382, ICEA P-45-482, and conductor melting curves in IEEE 242. Verify adequacy of phase conductors at maximum 3-phase bolted fault currents, equipment grounding conductors, and grounding electrode conductors at maximum ground-fault currents.

D. Coordination-Study Report:

1. Prepare a written report indicating the following results of coordination study:

a. Tabular format of settings selected for overcurrent protective devices:

1. Device tag.

2. Relay-current transformer ratios; and tap, time-dial, and instantaneous-pickup values.

3. Circuit breaker sensor rating; and long-time, short-time, and instantaneous settings.

4. Fuse-current rating and type.

5. Ground-fault relay-pickup and time-delay settings.

b. Prepare coordination curves to determine settings of overcurrent protective devices to achieve selective coordination. Graphically illustrate that adequate time separation exists between series devices, including power utility company's upstream devices. No more than 3 overcurrent protective devices shall be shown on a graph. All text descriptions indicated on the graphs shall be legible. Show the following specific information:

1. Device tag.

2. Voltage and current ratio for curves.

3. Three-phase and single-phase damage points for each transformer.

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

5. Cable damage curves.

6. Transformer inrush points.

7. Maximum fault-current cutoff point.

8. Calculated short circuit current at each bus as seen by the respective protective devices.

9. Selective coordination in the long time, short time and instantaneous regions of the phase and ground fault protection schemes.

c. Completed data sheets for setting overcurrent protective devices.

3.4 ARC FLASH STUDY

A. Perform arc-flash calculations to determine the information necessary to comply with the indicated labeling requirements in Paragraph, Arc Flash and Shock Warning Signs.

1. The study shall be based on NFPA 70E, including the guidance provided within the Annexes. Model the electrical system under normal operating conditions and with motors operating, during which normal maintenance would be undertaken. Arc flash calculations may require different short circuit system modeling then those required for the maximum available short circuit current study used to establish equipment short circuit ratings.

2. Calculations shall be performed using the IEEE 1584 equations. Calculate the arc flash hazard using both three phase bolted fault levels and arcing fault current levels. The highest incident energy level calculated shall be utilized to determine the maximum hazard/risk category.

3. Where equipment arc flash hazard ratings exceed Category 4 (40 cal./sq cm), the coordination study settings shall be reviewed and adjusted to reduce the arc flash hazard while still maintaining coordination. Provide recommended settings or other recommended methods in order to reduce the arc flash hazard to Category 4 or less.

4. Provide all new electrical distribution equipment (such as switchboards, panelboards, transformers, disconnects, etc.) with arc flash equipment labels per NEC 110.16 and NFPA 70E 130.3(C) and 130.7(E)(1). Indoor equipment label shall have a laminated protective cover. Outdoor equipment shall have nameplates in accordance with paragraph field fabricated nameplates. All arc flash labels shall include:

a. The header of the label shall be the capitalized word “WARNING” in black on an orange background. The word is to be preceded by the standard alerting symbol of an exclamation point in a black triangle and followed by a black lightning bolt in a black triangle.

b. Listing of the hazard: “ARC FLASH” and “SHOCK HAZARD”

c. Flash protection: Incident Energy (Cal/cm2) at 18”, flash protection boundary, and hazard/risk category number

d. Shock protection: voltage, and limited/restricted/prohibited approach boundaries

e. Equipment ID

f. Where equipment is fed from

g. Arc flash hazard calculation date

h. Equipment install date

3.5 OVERCURRENT PROTECTIVE DEVICE SETTING

A. Manufacturer's Field Service:

1. Engage a factory-authorized service representative of electrical distribution equipment being set and adjusted, to set overcurrent protective devices within equipment.

B. Testing:

1. Contractor will engage a qualified testing agency to perform device setting and to prepare test reports. After installing overcurrent protective devices and during energizing process of electrical distribution system perform the following device setting tests and prepare reports:

a. Verify that overcurrent protective devices meet parameters used in studies.

b. Adjust devices to values listed in study results.

c. Adjust devices according to recommendations in NETA ATS Inspection and Test Procedures.

END OF SECTION 26 05 73

SECTION 26 05 73 Page 1