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MV MetalClad Switchgear
- 1. 1 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear MV MetalClad Switchgear Still The Best MV Solution Gary H. Fox, PE GE Energy Senior Specification Engineer T 925 969 3608 C 510 219 6868 E gary.fox@ge.com www.geindustrial.com/design 2120 Diamond Blvd., Suite 100 Concord, CA 94520 General Electric Company San Francisco IEEE / IAS Electrical Design and Applications Seminar April 29,2011
- 2. 2 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear SAFETY FEATURES DEAD FRONT CONSTRUCTION CLOSED DOOR RACKING REMOTE BREAKER RACKING & CONTROL AVAILABLE PT & CPT ROLLOUT TRAYS BREAKERS CANNOT RACK IN/OUT IF CLOSED CANNOT CLOSE BREAKERS IF NOT FULLY RACKED IN SPRINGS DISCHARGE WHEN BREAKER IS MOVED MECHANICALLY INTERLOCKED SHUTTERS GROUND & TEST DEVICES AVAILABLE SAFE AUXILIARY SECONDARY FUSES ACCESSIBILITY EXTERNAL BREAKER POSITION INDICATOR FULLY ISOLATED 2-HIGH CABLE COMPARTMENTS
- 3. 3 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear MetalClad Switchgear & Breakers: ANSI C37.04 - AC Power Circuit Breaker rating Structure ANSI C37.06 - 1987 & 2000* - Preferred Ratings of Power Circuit Breakers ANSI C37.09 - Test Procedures for Power Circuit breakers ANSI C37.54 – Conformance Test Procedures ANSI C37.010 – Application Guide for Power Circuit Breakers ANSI C37.11 – Power Circuit Breaker Control Requirements ANSI C37.20.2 – Standards for Switchgear Assemblies NEMA SG-4 & 5 - Power Circuit Breakers & Switchgear Assemblies Optional: UL & CSA Listing *Why is there two years?? Codes & Standards
- 4. 4 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear ANSI C37.06-1987
- 5. 5 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear ANSI C37.06-2000
- 6. 6 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Voltage - 1.0 kV thru 15 kV Maximum Nominal Voltage Classes 4160V, 7200V, 13800V Short Circuit Current Ratings: Nominal MVA Classes 4160-250MVA - 29KA (sym) 4160-350MVA - 41KA 4160-450MVA - 63KA* 7200-500MVA - 33KA 7200-785MVA - 63KA * 13800-500MVA - 18KA 13800-750MVA - 28KA 13800-1000MVA - 37KA 13800-1500MVA - 63KA* Equipment & Breaker Ratings Maximum KA Ratings (ANSI 2000) 4760-31.5KA (sym) 4760-40KA 4760-50KA 4760-63KA* 8250-40KA 8250-50KA* 8250-63KA* 15000-20KA 15000-25KA 15000-31.5KA 15000-40KA 15000-50KA 15000-63KA * Exceed ANSI Preferred Ratings
- 7. 7 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear •Vacuum interrupters first conceived in the 1920’s, manufacturing of Vacuum Breakers began in 1961 •Vacuum breakers allowed 2-high drawout designs beginning in 1976 •5 Cycle (std) & 3 Cycle (optional) Interrupting Speed Capability •Reduced & Easier Maintenance Than Other Interrupting Designs, Such as SF6 & Air Magnetic Vacuum Interrupter
- 8. 8 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear VACUUM BREAKER CONSTRUCTION CONTINUOUS CURRENT - 1200A thru 4000A (forced air) Modular Phase Interrupters - Simple Replacement Copper Ground Bar Manual Trip/Close Button Operations Counter Spring Charge Indicator Rating Interference Plate Wheels On Frame For Mobility Contact Wear Indicator Mechanism Interrupter Assemblies Primary Disconnects Front Cover Secondary Disconnect
- 9. 9 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear All MetalClad meets Metal Enclosed, but Metal Enclosed gear does not meet MetalClad Requirements! Metal Enclosed Switchgear (C37.20.3) Completely enclosed Primary power circuit switching or interrupting devices Buses Connections Control and auxiliary devices. Access provided by doors or removable covers, or both. Metalclad Switchgear (C37.20.2) Main switching and interrupting device must be drawout. Circuit breaker (usual) or a load-break interrupter switch (unusual). Extensive barriering Shutters All live parts enclosed within grounded metal barriers Insulation-covered bus All compartments separated by metal barriers with no intentional openings.
- 10. 10 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear And there’s more to C37.20.2! Metal barrier in front of or part of switching device to ensure that no live parts are exposed when the outer cover is opened while in the connected position. Mechanical interlocks provided for proper operating sequence > Prevent movement while closed > Prevent closing unless disconnects are fully engaged or at safe distance > Prevent disconnection and access to primary fuses on CPT unless secondary open > Stored energy mechanisms cannot be discharged unless fully charged > Complete withdrawal not permitted until closing mechanism is blocked > Automatic discharge of stored energy mechanism before or in process of removal from housing > Provisions for locking to prevent moving into Connected position
- 11. 11 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear STANDARD Construction & Dimensions • Typical Indoor Dimensions: 95” H 36” W 94” D •36” Width Sections for Indoor and Outdoor CTs GSCT Cable Trough Surge Suppressors Main Bus Breakers Front Of Gear Standard 2-High Sideview
- 12. 12 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear SWITCHGEAR CONSTRUCTION BASICS Separate Breaker, Bus, & Cable Compartments, isolated with 11 gauge steel barriers. Bolted Steel Frame Construction, with gusseted corners – very rigid, stable NEMA 1 & 3R Construction Outdoor with or without aisle Closed Door Breaker Drawout 11 Gauge Steel Doors, (2) 14 Gauge Panels Between Sections All steel is either Zinc plated, or painted. No bare metal. Main Bus Compartment Cable Compartments Breaker Compartments
- 13. 13 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear SWITCHGEAR BUS BASICS 1200, 2000, 3000, 3500 & 4000* AMPS. (* 4000A breaker section is fan cooled) 80KA Asym. Bracing, 130KA Peak, Std. 6” Copper Bus Bars Full Tin Plate Standard, Silver Available. Note Silver is used on all sliding contact surfaces. All Phase Bus Fluidized Bed Epoxy Coated 1/4” X 2” Ground Bus Standard Polyester-Glass Supports Standard, Porcelain Optional Vinyl Boots With Nylon Hardware On Joints Fully Isolated with 11-Gauge Steel Riser Bus Main Horizontal Bus Bus Boot
- 14. 14 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear BREAKER/AUXILIARY COMPARTMENTS Polyester-Glass Primary Supports (std) Polyester-Glass or Steel Shutters, Mechanically Interlocked With Racking Mechanism in Breaker Compartments Max of 4 CTs Per Phase, Per Breaker On Primary Supports PT/CPT, 4 Trays Per Section PT/CPT Primary Fuses are Inaccessible unless Tray Is Disconnected Open / Close / Test Position Indicator Secondary Disconnect Block
- 15. 15 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear CABLE COMPARTMENT CONSTRUCTION Provision For Cable, Bus Duct, Potheads or REBs NEMA Drilling For 2-750 MCM Per Phase With Space For Stress Cones Steel Isolation Trough For 2- High Breaker Cables Front to Rear Control Wire Trough Mounting For Ground Sensor CT (GSCT) Arrestors, CPTS/CTS Surge Suppressors For Switching Transient Suppression on Feeders
- 16. 16 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Enclosures Indoor Indoor Drip-proof Outdoor, No Aisle Outdoor Protected Aisle Outdoor Common Aisle Indoor provided in Equipment Power Center Site Specific Seismic Withstand Levels: Ss, Sds
- 17. 17 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Covers Bolted rear covers with lifting handles Hinged rear covers Provisions for locks, rear and/or front IR Scanning Ports on rear covers
- 18. 18 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Did YOU Notice that ALL MV breakers are electrically operated ??????? Ac (120 V, 240 V) vs dc (48 V, 125 V) Trip and close circuits can be different PG&E requirements Microprocessor based relays require control power (ac not a good choice) Supplied from ??? CPTs – Line or bus connected Throwover contactors on multiple mains Integral branch panels not necessary
- 19. 19 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Control Wire/ Terminations Options Uninsulated spade, CT wiring with ring type Insulated terminals Ring type for all Origin/destination sleeves Short circuit type terminal blocks on CT secondary
- 20. 20 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Circuit Breaker 5 cycle std 3 cycle Capacitor Switching duty Auxiliary Contacts (MOC) Position Switch (TOC) Control voltage
- 21. 21 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Copper Main Bus Polyester bus supports Porcelain supports Tin plated joints Silver plated joints
- 22. 22 SF IAS ElectricalDesign Seminar April , 2011 Medium Voltage Switchgear Auxiliary Devices Surge Arresters, Class, Rating or indicate system grounding method Current Transformers, ratios and accuracy Potential Transformers Protective Relays Indicating Lights: Incandescent, LED Instrumentation & Power Metering Network Gateways, Switches Remote Racking Operator Breaker Test Cabinet (located external to switchgear) Ground and Test Device