Valdez Construction 6/12/2023 - Laserfiche WebLink

City of Everett 26 05 73.16 - 7 Inductive Charging Infrastructure for Everett Transit F. Study electrical distribution system from normal and alternate power sources throughout electrical distribution system for Project. Study cases of system-switching configurations and alternate operations that could result in maximum fault conditions. G. Transformer Primary Overcurrent Protective Devices: 1. Device must not operate in response to the following: a. Inrush current when first energized. b. Self-cooled, full-load current or forced-air-cooled, full-load current, whichever is specified for that transformer. c. Permissible transformer overloads according to IEEE C57.96 if required by unusual loading or emergency conditions. 2. Device settings must protect transformers according to IEEE C57.12.00, for fault currents. H. Motor Protection: 1. Select protection for low-voltage motors according to IEEE 242 and NFPA 70. 2. Select protection for motors served at voltages more than 600 V according to IEEE 620. I. Conductor Protection: Protect cables against damage from fault currents according to ICEA P-32-382, ICEA P-45-482, and protection recommendations in IEEE 242. Demonstrate that equipment withstands maximum short-circuit current for time equivalent to tripping time of primary relay protection or total clearing time of fuse. To determine temperatures that damage insulation, use curves from cable manufacturers or from listed standards indicating conductor size and short-circuit current. J. Generator Protection: Select protection according to manufacturer's instructions and to IEEE 242. K. Include ac fault-current decay from induction motors, synchronous motors, and asynchronous generators and apply to low- and medium-voltage, three-phase ac systems. Also account for fault-current do decrement, to address asymmetrical requirements of interrupting equipment. L. Calculate short-circuit momentary and interrupting duties for three-phase bolted fault and single line-to-ground fault at each equipment indicated on one-line diagram. 1. For grounded systems, provide bolted line-to-ground fault-current study for areas as defined for three-phase bolted fault short-circuit study. M. Protective Device Evaluation: 1. Evaluate equipment and protective devices and compare to short-circuit ratings. 2. Adequacy of switchgear, motor-control centers, and panelboard bus bars to withstand short-circuit stresses. 3. Application of series-rated devices must be recertified, complying with requirements in NFPA 70. 4. Include in report identification of protective device applied outside its capacity. 26 05 73.16 - 7 COORDINATION STUDIES