United States Department of Agriculture Design Guide for Rural Utilities Service Rural Substations RUS Bulletin 1724E-300 Issued June 2001 (BLANK PAGE) UNITED STATES DEPARTMENT OF AGRICULTURE Rural Utilities Service RUS BULLETIN 1724E-300 SUBJECT: Design Guide for Rural Substations TO: All RUS Borrowers RUS Electric Staff EFFECTIVE DATE: Date of approval. OFFICE OF PRIMARY INTEREST: Transmission Branch, Electric Staff Division. INSTRUCTIONS: This bulletin is an update and revision of previous REA Bulletin 65-1, “Design Guide for Rural Substations” (revised June 1978). Replace previous Bulletin 65-1 with this bulletin and file with 7 CFR Part 1724. AVAILABILITY: This bulletin is available on the Rural Utilities Service website at: http://www.usda.gov/rus/electric PURPOSE: This bulletin provides a basic design guide and a reference tool for designing rural substations. GENERAL: This Bulletin has been revised to bring the publication up to date with latest industry standards, current RUS format, and technical requirements. Our thanks to Cooperative Research Network of the National Rural Electric Cooperative Association, (NRECA) which has supported this project, and it's consultant Burns & McDonnell Engineering Company for the work which has made it possible to put this revision of the design guide together. The following current and former members of the Substation Subcommittee of the (NRECA), Transmission and Distribution (T&D) Engineering Committee provided invaluable assistance in preparing this document. 1. Bardwell, Jim, SGS Witter, Inc., Albuquerque, New Mexico 2. Chapman, George, Patterson & Dewar Engineers, Inc., Decatur, Georgia 3. Eskandary, Mike, USDA-RUS-ESD-TB, Washington, DC 4. Howard, Jerrod, Central Electric Power Co-op, Inc., Columbia, SC 5. Kahanek, Bil, Lower Colorado River Authority, Austin, TX 6. Myers, Tom, Berkeley Electric Co-op, Moncks Corner, SC 7. Malone, Ken, Middle Tennessee EMC, Murfreesboro, TN 8. Nicholson, Norris, USDA-RUS-ESD-TB, Washington, DC Bulletin 1724E-300 Page 5 TABLE OF CONTENTS ABBREVIATIONS AND ACRONYMS.......................................................................................... 31 CHAPTER 1 - INTRODUCTION.................................................................................................... 37 1.1 PREFACE........................................................................................................................ 37 1.2 PURPOSE AND SCOPE ................................................................................................. 37 1.3 RELATIONSHIP OF SUBSTATION TO OVERALL POWER SYSTEM......................... 37 1.4 IMPORTANCE OF ADEQUATE SUBSTATION PLANNING AND ENGINEERING............................................................................................................... 38 1.5 TYPES OF SUBSTATIONS............................................................................................. 38 1.5.1 General.............................................................................................................. 38 1.5.2 Distribution Substations ....................................................................................... 39 1.5.3 Transmission Substations ..................................................................................... 39 1.5.4 Switching Substations .......................................................................................... 39 1.6 REFERENCES................................................................................................................. 40 CHAPTER 2 - GENERAL DESIGN CONSIDERATIONS............................................................... 41 2.1 INITIAL AND ULTIMATE REQUIREMENTS ............................................................... 41 2.2 SITE CONSIDERATIONS............................................................................................... 41 2.3 ENVIRONMENTAL CONSIDERATIONS...................................................................... 42 2.3.1 General.............................................................................................................. 42 2.3.2 Weather............................................................................................................. 46 2.3.3 Altitude .............................................................................................................. 46 2.3.4 Earthquakes ....................................................................................................... 47 2.3.5 Other Considerations........................................................................................... 50 2.4 INTERFACING CONSIDERATIONS.............................................................................. 51 2.4.1 Line Tension....................................................................................................... 51 2.5 RELIABILITY CONSIDERATIONS ............................................................................... 51 2.6 OPERATING CONSIDERATIONS ................................................................................. 52 2.7 SAFETY CONSIDERATIONS......................................................................................... 52 2.8 MAINTENANCE CONSIDERATIONS........................................................................... 52 2.9 REFERENCES................................................................................................................. 52 CHAPTER 3 - DOCUMENTS ......................................................................................................... 55 3.1 GENERAL....................................................................................................................... 55 3.1.1 Possible Documents or Studies Required of the Engineer....................................... 55 3.2 NEED FOR DOCUMENTATION.................................................................................... 55 3.3 PROCEDURES................................................................................................................ 56 3.4 PROCUREMENT ............................................................................................................ 56 3.5 DRAWINGS .................................................................................................................... 57 3.5.1 General.............................................................................................................. 57 3.5.2 Quality ............................................................................................................... 57 3.5.3 Types of Drawings ............................................................................................. 59 3.6 STUDIES......................................................................................................................... 71 3.7 REFERENCES................................................................................................................. 71 Bulletin 1724E-300 Page 6 APPENDIX A—TYPICAL SUBSTATION DRAWING CHECKLIST....................................... 73 APPENDIX B—U.S. DEPARTMENT OF AGRICULTURE RURAL UTILITIES SERVICE SUBSTATION DESIGN SUMMARY ....................................................................... 91 1 INTRODUCTION ................................................................................................... 94 2 DESIGN CONSIDERATIONS................................................................................. 95 3 DOCUMENTS ........................................................................................................ 98 4 PHYSICAL LAYOUT........................................................................................... 100 5 MAJOR EQUIPMENT .......................................................................................... 104 6 SITE .................................................................................................................. 107 7 STRUCTURES...................................................................................................... 108 8 FOUNDATIONS................................................................................................... 109 9 GROUNDING....................................................................................................... 109 10 INSULATED CABLES AND RACEWAYS.......................................................... 111 11 CORROSION........................................................................................................ 112 12 PROTECTIVE RELAYING................................................................................... 112 13 INSTRUMENTS, TRANSDUCER, AND METERS ............................................... 114 14 SUBSTATION AUTOMATION............................................................................ 114 15 AC AND DC AUXILIARY SYSTEMS.................................................................. 115 16 CONTROL HOUSE .............................................................................................. 116 17 COMMUNICATIONS........................................................................................... 117 CHAPTER 4 - PHYSICAL LAYOUT ........................................................................................... 119 4.1 INTRODUCTION.......................................................................................................... 119 4.2 LAYOUT CONSIDERATIONS..................................................................................... 119 4.2.1 Initial Design Parameters .................................................................................