Y1DA--Project # 596A4-24-101 - Construction to Replace Main Electrical Distribution Equipment

Replace Main Electrical Distribution Equipment Project Number: 596A4-24-101 Bid Documents Coordination Study Northeast Infrastructure, LLC 34 Brown Street Honesdale, PA 18431 October 29, 2025 Lexington VAHCS Troy Bowling Campus 1101 Veterans Dr. Lexington, KY 40502 -- 1 of 31 -- LEXINGTON KY, VA MEDICAL CENTER MEDIUM VOLTAGE FAULT CURRENT AND COORDINATION STUDY NEW SWITCHGEAR 100% SUBMITTAL PROJECT NUMBER: 240121 31 OCTOBER 2025 Prepared By: Elizabeth Tuomey, PE Checked By: Daniel Morton, PE -- 2 of 31 -- Medium Voltage Fault Current and Coordination Study 31 October 2025 Lexington VAMC New Switchgear TOC-1 TABLE OF CONTENTS 1 EXECUTIVE SUMMARY ....................................................................................................1-1 1.1 Introduction ...................................................................................................................................................... 1-1 1.2 Calculations ....................................................................................................................................................... 1-1 2 SHORT CIRCUIT ANALYSIS .............................................................................................2-1 2.1 Introduction ...................................................................................................................................................... 2-1 2.2 Short Circuit Calculation Results............................................................................................................ 2-1 2.3 Equipment Evaluation Results ................................................................................................................ 2-1 3 PROTECTIVE DEVICE COORDINATION .......................................................................3-1 3.1 Introduction ...................................................................................................................................................... 3-1 3.2 Time-Current Characteristic Coordination Sheets ....................................................................... 3-1 APPENDIX A Short Circuit Current Calculation – Worst Case Single Source Scenario B One-line Diagram Scope of Coordination C Time Current Coordination Curves D Protective Device Settings E KU Short Circuit and Protective Device Data -- 3 of 31 -- Medium Voltage Fault Current and Coordination Study 31 October 2025 Lexington VAMC New Switchgear 1-1 1 EXECUTIVE SUMMARY 1.1 INTRODUCTION Wiley|Wilson is providing the medium voltage design for the Lexington VA Medical Center to replace the Tower Building Switchgear, Chiller Switchgear 1, and associated distribution equipment. The purpose of this calculation package is to present the Short Circuit and Coordination Studies included with the design. The new Tower switchgear consists of a 1200A 12.47kV double-ended four-section metal- clad switchgear, in a main-tie-main configuration. Each half of this switchgear consists of one main and two feeder breakers, with a tie breaker between them. The switchgear mains are fed from two separate feeder breakers in the VA-owned Main Building Switchgear that is immediately upstream. Also included in this design is the replacement of the 480V network protectors with high pressure safety switches on the secondary side of each of four Tower Building service transformers. The Chiller Switchgear consists of a unit-substation-like lineup, with a 480V double-ended switchgear in a main-tie-main configuration, each side fed by a 2500kVA dry-type 12470- 480V transformer and its associated 600A freestanding metal-clad circuit breaker. The short circuit study is intended to show minimum required equipment ratings with the designed feeder lengths. Another analysis will be required during construction to reflect actual conditions based on purchased equipment and installed feeder types and lengths. A coordination study has been performed for the medium voltage system using basis of design equipment to prove that proper coordination can be achieved. The Contractor will be required to provide their own coordination study based on actual equipment purchased to ensure that the equipment can meet code and project requirements. 1.2 CALCULATIONS This study includes short circuit calculations and overcurrent protective device coordination. All calculations have been performed using Power*Tools for Windows, a modular assembly of software developed by SKM Systems Analysis, Inc. The following modules have been used for this study: • System Model Development DAPPER • Short Circuit Calculations A_Fault • Protective Device Coordination CAPTOR -- 4 of 31 -- Medium Voltage Fault Current and Coordination Study 31 October 2025 Lexington VAMC New Switchgear 1-2 Version 10.0.0.1 of the Power*Tools software has been used for all of the calculations presented throughout this report. Additional information related to this software package can be found at www.skm.com. For this study, the purpose of the short circuit calculations is to determine available short circuit current levels throughout the electrical distribution system. The results of these calculations are used to confirm the short circuit interrupting and withstand ratings of designed equipment. These results can be found in Section 2 – “Short Circuit Analysis.” During the protective device coordination study, the ratings and settings of the proposed overcurrent protective devices are examined. In a selectively coordinated system, the protective device closest to the fault will interrupt the circuit thereby minimizing the disruption of electrical service. We have developed and plotted time current characteristic (TCC) coordination sheets showing the relationships between the relays in the Tower switchgear and the relays in the chiller switchgear transformer primary disconnects, the relays for the Main Switchgear breakers that feed them, the trip units in the contact switches and chiller switchgear main breakers, and…