9._Medium-Voltage_Gas_Switch.pdf

QUUG 11-1016 SOW

33 77 19.00 40-1

SECTION 33 77 19.00 40

MEDIUM-VOLTAGE GAS SWITCH

PART 1 - GENERAL

1.1 Section 26 00 00.00 20 BASIC ELECTRICAL MATERIALS AND METHODS apply to work specified in this section.

1.2 DESIGN REFERENCES: Provide the design and installation in accordance with the following references. This list is not inclusive and shall be used as a guide that shall be further developed by the Prime Contractor’s A-E hired firm. The publications are referred to in the text by the basic designation only.

AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI)

ANSI C37.72 (1987) Standard for Manually-Operated Dead-Front Pad Mounted Switchgear with Load Interrupting Switches and Separable Connections for Alternating-Current Systems

ASTM INTERNATIONAL (ASTM)

ASTM A123/A123M (2013) Standard Specification for Zinc (Hot-Dip Galvanized) Coatings on Iron and Steel Products

ASTM A153/A153M (2009) Standard Specification for Zinc Coating (Hot-

Dip) on Iron and Steel Hardware

ASTM D2472 (2000; R 2014) Standard Specification for Sulphur

Hexafluoride

INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)

IEEE 386 (2006; INT 1 2011) Standard for Separable Insulated Connector Systems for Power Distribution Systems Above 600V

IEEE C57.12.28 (2014) Standard for Pad-Mounted Equipment -

Enclosure Integrity

33 77 19.00 40-2

1.2 MINIMUM CONSTRUCTION SUBMITTALS: As determined during the design phase by the Designer of Record (DOR), additional submittals may be added to this outline list.

1.2.1 Shop Drawings

a. Connection Diagrams

b. Load- Break Switches

1.2.2 Product Data

a. SF6 Load-Break Switches

b. Space Heaters

c. Mounting Frames

d. Accessories

1.2.3 Test Reports

a. Basic Impulse Insulation Level (BIL)

b. Withstand Voltage Rating

c. Momentary RMS Asymmetrical Rating

d. Leak Tests

e. Final Test Reports

1.2.4 Operation and Maintenance Data

a. Switches

b. Space Heaters

1.3 MAINTENANCE MATERIALS SUBMITTALS: Submit operation and

maintenance manuals for switches, and space heaters.

PART 2 PRODUCTS

2.1 EQUIPMENT:

2.1.1 Sulphur-hexafluoride (SF6) switches: Load-interrupter switches and resettable, vacuum fault-interrupters, elbow-connected and enclosed in a submersible SF6-insulated, welded Type 304L stainless-steel tank and submersible wiring and control housings, suitable for installation in existing manholes/vaults. Large viewing windows for contact blades. Switches shall be installed in manholes but they will be able to be manually operated by maintenance personnel from the

33 77 19.00 40-3 outside, in a standing position with a lever tool. Bushings and bushing wells shall be suitable for immersed operation. Provided with voltage indicator. Number of ways shall be as required by application. Provide detail drawings that show mounting details and configuration for load-break switches. Electrical specifications:

Voltage rating: 15.5 kV Frequency: 60 Hz BIL Voltage: 95 kV Short Circuit Current: 12,500 amps symmetrical.

Main Bus current rating: 600 amperes continuous.

2.1.1.1 Provide gas insulated load-break switches of the vault type in accordance with ANSI

C37.72 and IEEE 386.

2.1.1.2 Provide sulphur hexafluoride (SF6) gas in accordance with ASTM D2472.

2.1.1.3 Provide manually operated, load-interrupting type SF6 load-break switches, rated

15.5 kV 600 amperes, minimum, continuous and load break for operation on a 12.47 kV, 3-phase, 3- or 4-wire system.

2.1.1.4 Provide switch enclosures in accordance with IEEE C57.12.28 equipped with ground bus capable of carrying the rated fault current for one second for each way.

2.1.1.5 Provide each switch with pressure gage, position viewing window and fill plug.

2.1.1.6 Provide lockable incoming line position of switches to prevent unauthorized grounding.

2.1.1.7 Provide cable and cable terminations in accordance with Section 33 71 02 UNDERGROUND ELECTRICAL TRANSMISSION AND DISTRIBUTION. Equip switches with 600 amperes and bushings with inserts to accept load break elbows, or as needed to fit in the new installation.

2.1.1.8 Provide cable terminations from the fuse compartment that are preformed stress-cones or have deep-well apparatus bushings in accordance with IEEE 386.

2.1.1.9 Provide provisions for padlocking each handle in any position.

2.1.1.10 Provide switch tanks that are constructed of stainless steel plate, fully welded.

33 77 19.00 40-4

2.1.1.11 Provide operating mechanisms that are equipped with handles for manual operation and are operated by a non-teasible, snap-action, quick-make, quick-break. Make opening and closing of the main contacts totally independent of the speed or position of the operating handle.

Secure operating handle to the shaft in a manner that ensures tightness and alignment. Operating mechanisms shall allow operation from the exterior of the manhole. Provide required tools for operation, at least one per switch provided under this project.

2.1.2 Space Heaters: Permanently mark connection diagrams for heater connections on drawings and shipping covers.

2.1.2.1 Equip ventilated cable termination compartment and the fuse compartment on outdoor switches with externally energized space heaters to provide approximately 4 watts/square meter of outer surface area. Provide heaters that have a power density that does not exceed 4 watts per 650 square millimeter of heater element surface. Provide heaters that are rated at 208 volts or at 120 volts, as required per project design. Locate heaters at the lowest portion of each space to be heated. Cover terminals. Use thermostats to regulate the temperature.

2.1.2.2 Provide installed and operable heaters at the time of shipment so that the heaters can be operated immediately on arrival at the site, during storage, or before installation. Mark connection locations prominently on drawings and shipping covers with temporary leads for storage operation easily accessible without removal of shipping protection.

2.1.3 Mounting Frames: Furnish mounting frames that are of angle-iron construction, for all vaul-mounted switches and are hot-dipped galvanized after fabrication in accordance with

ASTM A123/A123M ASTM A153/A153M.

2.1.3.1 After fabrication, clean and paint all exposed ferrous metal surfaces of the pad mount enclosure.

2.1.3.2 Paint mounting frames in accordance with ANSI C37.72.

2.2 ACCESSORIES:

2.2.1 Provide fittings, lifting eyes, insulators, and other required accessories with the switch as necessary.

2.2.2 Provide all corrosion-resistant metal operating parts of switch assemblies.

2.2.3 Provide switches with suitable attachments to permit closing and opening under full rated load current, without damage.

33 77 19.00 40-5

2.2.4 Provide fuses located in a separate compartment on the outgoing feedersInterlock fuse-compartment doors with switch mechanisms.

2.2.5 Provide switches with a visible break option that allows direct viewing of the switch contacts in the open and closed positions within the switch tank.

2.3 SLUDGE PUMPS:

2.3.1 Pump for manholes shall be of the submersible type, suitable for water, sludge and small solids and rated to prevent manholes to get flooded by penetration of water from the water table or rainstorms. Electrical supply shall be 120V/ 208V 60 Hz.

2.4 FACTORY FINISH:

2.3.1 Provide switches with the manufacturer's standard paint finish when used for most indoor installations. For harsh indoor environments provide with manufacturer’s recommended finish.

2.5 TESTS INSPECTIONS, AND VERIFICATIONS:

2.5.1 Factory Information: Ensure switch has momentary rms asymmetrical rating of 22.5 kA and a close rms symmetrical rating of 12.5 kA for 1 minute 60 Hz withstand voltage rating of 35 kV and basic impulse insulation level (BIL) of 95 kV. Provide the type of switch indicated, designed to show the internal wiring, indicating each switch position. Provide each switching way with [600A dead break] [200A deep well] bushings.

2.5.1.1 Provide test reports for the momentary rms asymmetrical rating, withstand voltage rating, basic impulse insulation level (BIL) in accordance with ANSI C37.72.

2.5.2 Shipping: Prior to shipment, ensure leak tests are performed and submit certification the completed switch assembly has a leak rate less than 0.0000001 cubic centimeters per second by a helium mass spectrometer test. Seal and fill switches with SF6 to a nominal 70 kilopascal positive pressure at 24 degrees C.

PART 3 EXECUTION

3.1 INSTALLATION: Install switches in accordance with the manufacturer's instructions. Include in the installation all necessary hardware, insulators, and connections to line wire or bus.

33 77 19.00 40-6

3.1.1 Coordination: Coordinate power fuses with the circuit breaker settings in the substation and with the transformer rating. Provide time-current characteristics, minimum melt and total clear times as required.

3.1.2 Grounding: Solidly bond tanks, mounting frames, and operating mechanisms to the station ground counterpoise in accordance with ANSI C37.72.

3.1.2.1 Identify incoming line position with a warning tag that states "CAUTION:

INCOMING LINE, DO NOT GROUND." or similar.

3.2 FIELD TESTING: Disconnect load break switch assembly from the power supply and feeder cables and ground the switch enclosure before conducting insulation and high-voltage tests.

3.2.1 Give load break switch assembly an insulation-resistance test with a 5000V insulation-resistance test set.

3.2.2 Apply all tests for not less than 5 minutes and until three equal consecutive readings one minute apart are obtained. Record readings every 30 seconds during the first 2 minutes and every minute thereafter. Minimum acceptable resistance readings are 100 megohms.

3.2.3 Upon satisfactory completion of the insulation-resistance test, subject the load break switch to a high-voltage, 60-Hz withstand test. Make test voltage equal to 75 percent of the factory test values and apply for one minute.

3.2.4 Upon satisfactory completion of the high-voltage, 60-Hz withstand test, give the switch assembly a second insulation-resistance test as before. Provide results of the second insulation-resistance test that are within 5 percent of the first test values and that indicate no evidence of permanent injury by the high potential test.

3.2.5 Operate switch assembly in the presence of the Contracting Officer. Provide final test reports to the Contracting Officer. Provide a cover letter/sheet with the reports clearly marked with the System Name, Date, and the words "Final Test Reports - Forward to the Systems Engineer/Condition Monitoring Office/Predictive Testing Group for inclusion in the Maintenance Database."

*** END OF SECTION ***