Valdez Construction 6/12/2023 - Laserfiche WebLink

City of Everett 26 05 73.19 - 5 Inductive Charging Infrastructure for Everett Transit B. Preparatory Studies: Perform Short-Circuit and Protective Device Coordination studies prior to starting Arc-Flash Hazard Analysis. 1. Short-Circuit Study Output: As specified in "Short-Circuit Study Output Reports" Paragraph in "Short-Circuit Study Report Contents" Article in Section 260573.13 "Short-Circuit Studies." 2. Coordination Study Report Contents: As specified in "Coordination Study Report Contents"Article in Section 260573.16 "Coordination Studies." C. Calculate maximum and minimum contributions of fault-current size. 1. Maximum calculation must assume maximum contribution from utility and must assume motors to be operating under full-load conditions. 2. Calculate arc-flash energy at 85 percent of maximum short-circuit current in accordance with IEEE 1584 recommendations. 3. Calculate arc-flash energy at 38 percent of maximum short-circuit current in accordance with NFPA 70E recommendations. 4. Calculate arc-flash energy with utility contribution at minimum and assume no motor contribution. D. Calculate arc-flash protection boundary and incident energy at locations in electrical distribution system where personnel could perform work on energized parts. E. Include medium- and low-voltage equipment locations, except equipment fed from transformers smaller than 75 kVA. F. Calculate limited, restricted, and prohibited approach boundaries for each location. G. Incident energy calculations must consider accumulation of energy over time when performing arc-flash calculations on buses with multiple sources. Iterative calculations must take into account changing current contributions, as sources are interrupted or decremented with time. Fault contribution from motors and generators must be decremented as follows: 1. Fault contribution from induction motors must not be considered beyond three to five cycles. 2. Fault contribution from synchronous motors and generators must be decayed to match actual decrement of each as closely as possible (for example, contributions from permanent magnet generators will typically decay from 10 p.u. to 3 p.u. after 10 cycles). H. Arc-flash energy must generally be reported for maximum of line or load side of circuit breaker. However, arc-flash computation must be performed and reported for both line and load side of circuit breaker as follows: 1. When circuit breaker is in separate enclosure. 2. When line terminals of circuit breaker are separate from work location. I. Base arc-flash calculations on actual overcurrent protective device clearing time. Cap maximum clearing time at two seconds based on IEEE 1584, Section B.1.2. 26 05 73.19 - 5 ARC-FLASH HAZARD ANALYSIS