3. 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
4.
5. 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