Section 16055 - Overcurrent Protective Device Coordination

Overcurrent Protective Device Coordination ME- Building Group

SECTION 16055 - OVERCURRENT PROTECTIVE DEVICE COORDINATION

PART 1 - GENERAL

0.1 SUMMARY

A. This Section includes computer-based studies of overcurrent protective devices, calculations of fault currents, and recommendations for system coordination.

0.2 SUBMITTALS

A. Product Data and Certificates: For computer software. Certify compliance with IEEE 399.

B. Qualification Data: For study specialist. 1. Experience history and license data of the engineer responsible for the studies.

C. Fault Current Study Report

D. Coordination Study Report

0.3 QUALITY ASSURANCE

A. Software: Perform studies using computer and software. 1. Manual calculations are not acceptable. 2. Comply with IEEE 399 for general study procedures. 3. Comply with IEEE 242 for short-circuit current calculation and coordination time intervals.

B. Study Specialist: Organization or individual experienced in performance of studies. 1. Licensed Professional Engineer to perform, or direction performance of, the study. a. Experienced in performance of studies of similar magnitude with similar software.

C. Testing Agency Qualifications: Member company of the InterNational Electrical Testing Associ- ation. 1. Testing Agency's Field Supervisor: Person currently certified by the InterNational Electri- cal Testing Association to supervise testing specified in Part 3.

PART 2 - PRODUCTS

0.1 COMPUTER SOFTWARE DEVELOPERS

A. Computer Software Developers: 1. Subject to compliance with requirements, perform the studies using computer software programs developed by one of the following: a. CYME International, Inc. b. EDSA Micro Corporation. c. Electrical Systems Analysis, Inc. d. SKM Systems Analysis, Inc.

of 4 Revision Date: 12/17/04 Project & Bid Package File name:0bb3061c20562940cddba35446166da5.doc

PART 3 - EXECUTION

0.1 EXAMINATION

A. Examine existing conditions for device ratings, coordination requirements and other conditions affecting performance of the studies. 1. Use data for devices installed, or approved for installation.

0.2 FAULT CURRENT STUDY

A. Input data to support the fault current study: 1. Designations in the study consistent with the electrical distribution system diagrams 2. Impedance of utility service entrance. a. Utility Company source impedance and fault current contribution data. b. Infinite Bus source if Utility Company data is not available. c. Other impedance in accordance with IEEE 242. 3. Electrical distribution system diagram. a. Circuit breaker and fuse types and current ratings. b. Power transformer kVA, voltages, winding connections, impedance, and X/R ratios c. Generator kVA, voltage, and impedances d. Conductor sizes, insulation and length e. Conduit material, magnetic or non-magnetic. f. Busway current rating and impedance. g. Motor horsepower and code letter designation per NEMA MG 1. 4. Supplemental data, cross-referenced with tag numbers on diagram. a. Overcurrent protective device settings or types stipulated by utility company. b. Panelboard, switchboard, and motor-control center interrupting current ratings.

B. Calculate fault current available at each node in the system from normal and alternate sources. 1. Identify system configurations and operations resulting in maximum fault conditions.

C. Fault Current Report: 1. Tabulate the calculated maximum values for 3-phase, phase-to-phase, and phase-to- ground faults, at each node in the electrical distribution system. a. Momentary withstand duty (1/2-cycle) b. Interrupting duty (5-cycle) c. Long time duty (30-cycle) 2. Include a single-line electrical distribution system diagram that identifies calculated X/R ratios and 5-cycle interrupting duty fault currents.

D. Equipment Evaluation Report: 1. Prepare a report comparing fault current ratings of equipment with calculated fault current momentary withstand and interrupting duties. a. Tabulate calculated duties based on maximum available fault current. b. Highlight equipment with rated duties below calculated duties. 2. Verify that interrupting ratings of overcurrent protective devices comply with the following: a. Low-Voltage Circuit Breakers: IEEE 1015 and IEEE C37.50. b. Low-Voltage Fuses: IEEE C37.46. c. Circuit Breakers: IEEE C37.13.

0.3 COORDINATION STUDY

A. Input data to support the coordination study: 1. Data used as input for fault current study. 2. Designations in the study consistent with the electrical distribution system diagrams 3. Electrical distribution system diagram showing the following: a. Load current basis for sizing the ratings of circuits for cables and equipment. b. Circuit breaker and fuse types and current ratings. c. Relays and associated current transformer ratings and ratios. d. Power transformer kVA, voltages, winding connections, impedance, and X/R ratios e. Generator kVA, voltage, and impedances f. Conductor sizes, insulation and length g. Conduit material, magnetic or non-magnetic. h. Busway current rating and impedance. i. Motor horsepower and code letter designation per NEMA MG 1. 4. Supplemental data, cross-referenced with tag numbers on diagram. a. Motor load data, including non-standard inrush current, starting time and frequency of starts b. Motor thermal damage curve c. Motor starting scheme d. Power transformer magnetizing inrush current and continuous load ratings e. Ratings, types, and settings of utility company's overcurrent protective devices. f. Time-current-characteristic curves of devices indicated to be coordinated. g. Circuit breaker manufacturer, frame size, interrupting rating, current sensor rating, long time, short time, and instantaneous adjustment ranges. h. Protective relay manufacturer, type, ampere tap, time delay, and instantaneous at- tachment adjustment ranges.

B. Protection Standards 1. Overload and overcurrent protection of circuit elements and devices per NFPA 70 2. Fault current and time interval limits per IEEE 242 3. Transformer Primary Overcurrent Protective Devices: a. Permissible transformer overloads per IEEE C57.96. b. Fault current protection per IEEE C57.12.00. 4. Motor Protection for motors served by voltages greater than 600 V per IEEE 620 5. Conductor protection per ICEA P-32-382, ICEA P-45-482, and conductor melting curves in IEEE 242.

C. Coordination Study Report 1. Recommended Device Settings: Include tabulated settings for each adjustable device. a. Device tag. b. Relay tap, time-dial, and instantaneous settings. c. Circuit breaker sensor rating, long-time, short time, I2T, and instantaneous settings. d. Circuit breaker ground fault pickup and time delay settings. e. Ground-fault relay pickup and time delay settings. 2. Recommended Fuses: Include tabulated fuses ratings if different than indicated. a. Device tag. b. Indicated fuse class, type and rating c. Recommended fuse class, type and rating

3. Graphical Time-Current Plots: Prepare graphs to demonstrate that recommended settings produce selective coordination. Include the following information. a. Device tags. b. Voltage and current axis scale factors. c. Minimum melting and maximum clearing curves for fuses. d. Cable damage curves. e. Transformer damage curves f. Transformer inrush points. g. Maximum fault current cutoff point on each curve.

0.4 OVERCURRENT PROTECTIVE DEVICE SETTING

A. Manufacturer's Field Service: A factory-authorized service representative will assist in setting of overcurrent protective devices.

B. Protective Device Testing and Setting: Owner will engage a qualified testing agency to perform protective device testing and setting. 1. Verify that devices installed match devices tabulated in Recommended Device Settings. 2. Adjust devices to values listed in study results Recommended Device Settings. 3. Test devices per Chapter 7, "Inspection and Test Procedures," and Tables 10.7 and 10.8 in NETA ATS.

END OF SECTION