Design Guide for Rural Substations

1 United StatesDepartment ofAgricultureRuralUtilitiesServiceRUS Bulletin1724E-300 IssuedJune 2001 Design Guide forRural Substations (BLANK PAGE)UNITED STATES DEPARTMENT OF AGRICULTURER ural Utilities ServiceRUS BULLETIN 1724E-300 SUBJECT: Design Guide for Rural SubstationsTO: All RUS Borrowers RUS electric StaffEFFECTIVE DATE: Date of OF PRIMARY INTEREST: Transmission Branch, electric Staff : This bulletin is an update and revision of previous REA Bulletin 65-1, DesignGuide for Rural Substations (revised June 1978). Replace previous Bulletin 65-1 with this bulletinand file with 7 CFR Part : This bulletin is available on the Rural Utilities Service website at: : This bulletin provides a basic Design Guide and a reference tool for designing : This Bulletin has been revised to bring the publication up to date with latest industrystandards, current RUS format, and technical thanks to Cooperative Research Network of the National Rural electric Cooperative Association,(NRECA) which has supported this project, and it's consultant Burns & McDonnell EngineeringCompany for the work which has made it possible to put this revision of the Design Guide following current and former members of the Substation Subcommittee of the (NRECA),Transmission and Distribution (T&D) Engineering Committee provided invaluable assistance inpreparing this Bardwell, Jim, SGS Witter, Inc.

2 , Albuquerque, New Mexico2. Chapman, George, Patterson & Dewar Engineers, Inc., Decatur, Georgia3. Eskandary, Mike, USDA-RUS-ESD-TB, Washington, DC4. Howard, Jerrod, Central electric Power Co-op, Inc., Columbia, SC5. Kahanek, Bil, Lower Colorado River Authority, Austin, TX6. Myers, Tom, Berkeley electric Co-op, Moncks Corner, SC7. Malone, Ken, Middle Tennessee EMC, Murfreesboro, TN8. Nicholson, Norris, USDA-RUS-ESD-TB, Washington, DCBulletin 1724E-300 Page 5 TABLE OF CONTENTSABBREVIATIONS AND 1 - AND OF SUBSTATION TO OVERALL POWER IMPORTANCE OF ADEQUATE SUBSTATION PLANNING OF 2 - GENERAL Design AND ULTIMATE RELIABILITY OPERATING SAFETY MAINTENANCE 3 - Documents or Studies Required of the FOR of 1724E-300 Page 6 APPENDIX A TYPICAL SUBSTATION DRAWING B DEPARTMENT OF AGRICULTURE Rural UTILITIESSERVICE SUBSTATION Design CABLES AND , TRANSDUCER.

3 AND AND DC AUXILIARY 4 - PHYSICAL Design of Switching Distribution Primary Protective Breaker/Recloser Bypass Transmission Breaker Bypass Switching 1724E-300 Page BUS and Transfer Breaker Double Switching Scheme OF SUBSTATION Stroke Apparatus BUS for Rigid Bus Design BUS for Strain Bus OF MOBILE TRANSFORMERS AND and Maneuverability of the Location and and Secondary System LEGEND FOR 5 - MAJOR 1724E-300 Page Operation of and Oil Preservation Tests and and CIRCUIT of Circuit and Auxiliary Power and VOLTAGE CAPACITOR 1724E-300 Page and Short-Circuiting of Capacitor and Technical of Air Constructions of Outdoor Air Service of (Standard Definitions).. vs. Ungrounded Guide for Silicon-Carbide Valve Guide for Metal Oxide Surge at Line CIRCUIT Classifying and 1724E-300 Page CAPACITORS AND COUPLING CAPACITOR Capacitor Voltage Rotation Included with the Mobile 6 - SITE OF GRADED Yards (Two or More Levels).

4 Drainage Drainage CONSIDERATIONS AND and AND OTHER Access in the Substation SURFACING 1724E-300 Page C SAMPLE SUBSTATION SECURITY FENCE 7 - STRUCTURE Support Support Substation MEMBER Support Support Combination for Design COMPUTER D RISA-3D INPUT AND OUTPUT FOR A SIMPLE T 1724E-300 Page 12 CHAPTER 8 - Shafts (Piers).. Shaft Shaft Design (Line Support Structure).. and Uplift Capacity (Drilled Shafts).. on Retention Separator E SPECIFICATION FOR PROCURING GEOTECHNICALSUBSURFACE 9 - Fault Potential Rise (GPR).. RESISTIVITY Soil Resistivity Soil OF THE GROUND FAULT Grid the Split Factor, Decrement Factor, Grid 1724E-300 Page Conductor Equipment Ground Ground Grid Conductor Sizing from Equipment and Structures to Ground Limits of Body Shock TOUCH AND STEP SURFACE MATERIAL AND REDUCTION FACTOR Factor OF A SUBSTATION GROUNDING Design Mesh Voltage (Es).

5 Potential Rise (GPR).. of Equations for Em and of Computer Analysis in Grid Danger of Transferred of Sustained Ground 10 - INSULATED CABLES AND Insulation and of Control CABLE OVER 600 Shielded Power Cable (2 kV up to 35 kV).. Voltage 1724E-300 Page and Power Cable (69 kV up to 230 kV).. Conduit (Duct Bank).. UNDERGROUND Cable OVERHEAD 11 - of PREVENTIVE of AND Resistivity Corrosion Conditions from DC Potential 1724E-300 Page 15 CHAPTER 12 - PROTECTIVE of Protective of Defective Equipment or Abnormal Input RELAY Overcurrent Line F STANDARD DEVICE FUNCTION G SUGGESTED SUFFIX 13 - INSTRUMENTS, TRANSDUCERS, AND AND of Instruments and of of Instruments and Instrument 1724E-300 Page of electric Watt-Hour and Demand of Meter Indicating and Recording of Watt-Hour and VAR-Hour and Calculated 14 - SUBSTATION VS.

6 PROPRIETARY AUTOMATION ACQUISITION AND CONTROL Host Electronic Logic Local Area H GLOSSARY OF 15 - AC AND DC AUXILIARY AUXILIARY Loads AUXILIARY Loads of Loads and Duty 16 - CONTROL HOUSE HOUSE 1724E-300 Page and Relay House HVAC House 17 - Line or Audio Tone on Shield I GLOSSARY OF 18 - with Diagnostic Online Test Inspection of Major Inspection of Transformers and of , Disconnects, and Other On-Load Tap Circuit 1724E-300 Page 19 - After OF Resistance Factor High Potential Absorption Over-Potential Resistance Resistance Oil Gas Gas Analyzer Overcurrent Ratio Relay System Calibration Grid Resistance 20 - 1724E-300 Page 21 - UPRATING AND EXPANDING EXISTING Equipment FOR UPRATING OR NEW VS. UPRATING OR SUBSTATION 1724E-300 Page 20 LIST OF FIGUREST hese exhibits are available electronically as well as in hard TITLE 2-1 Basic Wind Zone Map of the United Transformer with Voltage Regulator with Bypass Stick-Operated Disconnecting Gang-Operated Disconnecting Switch with Horn Gaps andGrounding Double Side-Break Disconnecting Switch with Motor Circuit Capacitor with Voltage Capacitor, Wave Trap, Tuning Unit.

7 And Power Line Diagram Relay and Meter One-Line Switching One-Line Functional Relaying One-Line Plan View Showing Space for Equipment Distribution Regulator Bypass Circuit Breaker/Recloser Bypass of Tandem Switches for Circuit Breaker/Recloser Transmission Circuit Breaker Bypass Switching Bus Low Bus High and Transfer Bus Low and Transfer Bus High 1724E-300 Page 21 FIGURE TITLE 4-16 Double Breaker Double of Protection for Masts and Shield Wires Using Fixed Angle of Rolling Post Clearance to electric Supply Station Coefficients for Structural Bus System Illustrating Provisions for Conductor Thermal Configuration for Strain Bus Insulator Methods of Oil Dead Tank Live Tank Three-Pole Single-Throw SF6 Gas Circuit Type SDV Vacuum Circuit Relation of Symmetrical Interrupting Capability, Closing Capability, Latching Capability, and Carrying Capability to Rated Short-Circuit Ratio of Circuit Breaker Asymmetrical to Symmetrical Interrupting Single-Aisle Metal-Clad Switchgear with Typical Single-Aisle Switchgear Single-Phase Voltage Three-Phase Voltage Typical Capacitor Bank Two Three-Phase Capacitor Racks Connected toForm a Two-Step Bank.

8 Floating Wye with a Common A Y-Y Connected Capacitor Bank with One Series Section per Phase andNeutrals Typical Capacitor Bank Grd Wye Typical Capacitor Bank Floating Typical Capacitor Bank Wye Wye A Complete Typical Capacitor Equipment Connected Grd Wye with TwoSeries Sections/Phase in a Single Typical Internally and Externally Fused Capacitor Capacitors Vertically Capacitors Horizontally Horizontally Mounted Double-Break Switch with Grounding Horizontally Mounted Double-Break Horizontally Mounted Vertical-Break Interrupter Vertically Mounted Vertical-Break Tilting Insulator Single Side-Break Underhung Center-Break Hook Stick Switches on Structure at Termination of Bus from Vertical Reach 1724E-300 Page 22 FIGURE TITLE 5-31 Arrangement of Bolt Hole Centerlines in Terminal Outdoor Air Switch Hook Coefficient of Grounding for Various System Typical Voltage Time Curve for Coordination of Arrester Protective Levelswith Insulation Withstand Strength for Liquid-Filled Typical Volt Time Curves for Coordination of Metal Oxide Surge ArresterProtective Levels with Insulation Withstand Gapless Metal Oxide Surge Shunt-Gapped Metal Oxide Surge Series-Gapped Metal Oxide Surge Typical 60-Hz Temporary Overvoltage Capability for Metal Oxide Typical Volt Time Curve for Coordination of Arrester Protective Levels withInsulation Withstand Strength for Liquid-Filled Typical Volt Time Curves for Coordination of 152-kV MCOV Metal OxideSurge Arrester Protective Levels with Insulation Withstand Typical Volt Time Curves for Coordination of 140-kV MCOV Metal Oxide Surge Arrester Protective Levels with

9 Insulation Withstand Maximum Safe Separation Distance of Lightning Arresters from ProtectedEquipment Nominal System Voltage 23 kV Through 46 Maximum Safe Separation Distance of Lightning Arresters from ProtectedEquipment Nominal System Voltage 69 kV Through 138 Maximum Safe Separation Distance of Lightning Arresters from ProtectedEquipment Nominal System Voltage 161 kV Through 345 Typical Single-Phase Hydraulically Controlled Oil Circuit Recloser with Single-Phase Tripping and Three-Phase Typical Line Diagram of Distribution Circuit Showing Application of Operating Mechanism with Housing Cover Unit Recloser Operating Sequence Upon Occurrence of a Permanent Mounted 55 C Rise Current Transformer Basic Loading Characteristics (in Air)..3805-54 Bushing, Window, and Wound-Type Current High-Voltage Current Voltage Typical Primary Connections for Voltage Coupling Capacitor with Carrier Typical Coupling Capacitor Voltage Transformer with Carrier Coupling Capacitor Voltage Transformers with and Without Wave Yard on Moderately Sloped , 30-Minute Rainfall Intensity (cm/hr).

10 4176-52-Year, 30-Minute Rainfall Intensity (inches/hr)..4176-6 Fence Erection 1724E-300 Page 23 FIGURE TITLE 7-1 Single-Phase Bus Structure Short-Circuit Structure Wind Structure Ice Structure Seismic Structure Deflection Equivalent Structure Short-Circuit Structure Wind Shaft Force and Moment Shaft Elevation Shaft Shaft Elevation Alpha Function for Drilled Frost-Depth Contours of the United Footing Footing with e < Footing with e > Footing Footing Footing 3D Footing 2D Slab Separator Four-Pin Within Local Substation, Local Neutral Within Local Substation, Neutral Grounded at Remote in Substation, System Grounded at Local Substation and Also at Other Current Division for a Fault on High Side of Distribution Approximate Split Factor Sf, 100% Remote.