SECTION MEDIUM VOLTAGE ELECTRICAL DISTRUBUTION (ABOVE 600 VOLTS)

Transcription

1 SECTION MEDIUM VOLTAGE ELECTRICAL DISTRUBUTION (ABOVE 600 VOLTS) UNIVERSITY OF SOUTH ALABAMA REFERENCE INFORMATION University s Design and Construction Standards, one line diagrams, campus power plan, and 15 kv details of the Primary System feeders available for consultant review. PRIMARY POWER The University Campus Distribution System is kv (12,470 Volts), 3 phase. 4 wire, solidly grounded wye connected system with two utility substation transformers, Sub I rated at 115 kv primary, 15/20/25 mva, 8.38% Z, Sub II rated at 115 kv primary, 15/20/25 mva, 8.38 % Z. PRIMARY DISTRIBUTION SYSTEM The University campus is served by multiple radial feeders, 15 kv feeder system from the Electrical Switching Stations Sub I on Jaguar Dr. and Sub II on Cleverdon Pwky.. Each primary radial serves multiple buildings that have the same potential of being fed from one of two sources for isolation purposes. SERVICE CONNECTION Any new building which is energized from the Campus 15kV Distribution System for the first time must have approval by the University Electrical Distribution Superintendent. One week minimum notice is required. The Engineer of Record shall determine from which manhole to secure 15 kv service, verify connection possibilities, and shall indicate the ductbank on power plans as to the exact routing and configuration. This design shall be submitted to the University Electrical Superintendent for review. A typical service for a new building shall consist of a 15 kv pad-mounted switch, pad mounted transformer(s) and primary and secondary cables which shall be installed in a concrete encased, re-bar reinforced PVC conduit duct. Use galvanized rigid conduit with asphaltum (two coats) for all bends, use galvanized rigid conduit long radius factory elbows with asphaltum (two coats) for all primary ductbank 90 degree bends. 15 kv EQUIPMENT All 15 kv equipment including loop switches, pad mounted transformers, primary cable, lightning arrestors, cable elbows, 15 kv splices, primary ductbank and manholes shall be specified using the University's Design and Construction Standards. We expect full compliance. Pad-Mounted Primary Service Loop Switches: Provide one air switch (2 Feeders & 2 Taps) with 14 base extension or, where specifically designated by University Electrical Distribution Superintendent, semi or fully flush SF6 gas Load-interrupter switches and resettable fault interrupters with microprocessor-based overcurrent control switch in concrete vault for each building. Provide at least one spare position to accommodate future primary circuit connections. The loop switch shall be manufactured by S&C, G&W Electric Co. or Federal Pacific. All terminations shall be rated 600A. UPDATED NOVEMBER 27, 2017 Page 1 of 5

2 The service capacity of the transformers must be determined based on a load analysis of the connected building loads. The transformer must have 50% spare capacity over calculated load. The pad-mounted transformer shall be installed at least 10 feet from the building. There shall be at least ten feet clear space in front of the doors of each transformer and loop switch. Supply each transformer with a feeder coming from the loop switch. In large research buildings where feasible, provide two pad mounted transformers with double-ended switchgear with a secondary tie-breaker to ensure continuity of service. The Pad-Mounted Transformer shall be manufactured by ABB, VanTran, or Cooper. Provide bayonet expulsion type fuses in series with internal partial range current limiting fuses, sized as recommended by the transformer manufacturer. The transformer shall have copper windings. The insulating fluid shall be FR3 Environmentally Friendly seed based dialectric fluid as listed in current NEC Code. Transformer manufacturer shall place a Nitrogen Blanket on top of this fluid prior to shipment. Place drain valve in the high voltage compartment. Provide secondary bushing supports at the end of the bushing spade. High voltage bushings shall be 600 amperes with 600 ampere wells with inserts. Provide 300A. Hi-voltage switch, make-and-latch rating of 10-kA RMS, symmetrical, arranged for loop feed with 3-phase, 4-position, gang-operated, load-break switch that is oil immersed in transformer tank with hook-stick operating handle in primary compartment.. DRAWINGS DEPICTING 15kV Exact routing of all duct banks must be shown in plan and all existing utilities in the area of the routing must be shown on this drawing. Manholes shall be no more than 400 feet apart and shall have oversized diameter covers to facilitate wire pulling (see below). Elevations of all duct banks including wire content of conduit must be shown where leaving manholes, loop switches, transformers, etc. For new buildings the placement within the loop shall be depicted on a partial 15 kv single line drawing. USA standard details shall be used for manhole construction, ductbank construction, transformer/pad installation and loop switch/pad installation. Manhole splicing details shall be shown for every manhole, which is impacted by the project. 'Typical' splice details are not acceptable. Show the actual configuration including modifications, which is required by the project. The actual configuration shall include physical location of all splice locations and cable locations. Both before and after configurations shall be shown. METERING Each main switchboard or main panelboard shall have a Square D PM820, multi-functional digital meter compatible with campus energy management system and existing software. MEDIUM VOLTAGE CABLE The 15kV medium voltage cable shall be manufactured by Okonite, Southwire, or Kerite. UPDATED NOVEMBER 27, 2017 Page 2 of 5

3 The 15 kv cable shall have copper conductor, EPR - 133% level insulation, and copper tape shield with an overall jacket. See University guide specifications for more detailed information. All 15kv cable must be Hi-pot tested to the full level recommended by the manufacturer. Testing will be provided by the University of South Alabama through a third party testing agency. Coordinate all testing through the Superintendent of Electrical Distribution. All cables in manholes shall be fireproofed. Apply arc-proofing tape in one half-lapped layer with coated side toward cable. Band arc-proofing tape with 1-inch- wide bands of half-lapped, adhesive, glass-cloth tape 2 inches o.c. Arc proof tape shall be 3M #77, Plymouth Plyarc or approved equivalent. MEDIUM VOLTAGE TERMINATIONS AND SPLICES The Electrical Contractor shall use a 15 kv cable splicer approved by the University Electrical Distribution Superintendent to do all terminations and splicing. The re-connectable terminations, splices and elbows shall be manufactured by 3M Electrical Products Division or Tyco (dead breaks only). Substitutions are unacceptable. 1) Outdoor a) AWG #4/0 - #7694-S-4 b) 500 KCMIL - #7695-S-4 2) Indoor a) AWG #4/0 - #7624T-110 b) 500 KCMIL - #7625T-110 3) In-line Splice a) AWG #4/0-5514A b) 500 KCMIL A 4) 600A Dead-Break Elbows a) 5815 Series b) Tyco ELB-15/ In-line Splice bodies shall be properly grounded in manholes. CONCRETE ENCASED PRIMARY DUCTBANK SYSTEMS Duct banks shall be installed by qualified electrical contractors. All duct shall be installed in such a manner to prevent accumulation of water. The University standard for main duct bank runs is a 4-way duct bank with concrete encased 5 inch. There shall be at least two spares for every duct that is used in each of the 15 kv duct banks that are installed on a project. The top of the concrete encasement shall be a minimum of 24 inches below final grade. In special cases, this requirement shall be waived where field conditions require. However, such conditions must be approved by the University Electrical Distribution Superintendent and shall be considered the last resort in correcting the situation PVC conduit equal to Carlon # All connections solvent welded. Ducts shall be furnished in minimum 10 foot lengths. UPDATED NOVEMBER 27, 2017 Page 3 of 5

4 Use galvanized rigid conduit with asphaltum (two coats) for all bends. Use galvanized rigid long radius factory elbows (36 radius) with asphaltum (two coats) for all primary ductbank 90 degree bends. Use compound on all duct and conduit couplings. All duct and conduit couplings shall be watertight. Terminate duct with end bells equal to OZ/Gedney Type TNS. Base and intermediate spacers shall be Carlon catalog #S288PL and #S289PL or equivalent. Spacers shall be provided on maximum 5 foot centers and closer where required. Longitudinal and lateral re-bar shall be used for support in the ductbank Minimum reinforcing of the concrete shall be #4 re-bar. Ductbank rebar shall be grounded and bonded to the grounding systemat all ends. After ducts are installed, they shall be tied down to prevent floating. All soil, mud and debris shall be removed from ducts, conduits, spacers, rebar etc., before concrete is poured. Concrete shall cover the duct a minimum of 3 in all directions, and a maximum of 6. Rebar must be supported away from earth with minimum 1.5 concrete. After duct encasement is placed, and before backfill or cable is installed, pull a mandrel equal to 80 % of duct diameter through each duct. If this test indicates that there are obstructions in the duct system, that section of the system shall be removed and a new section installed at no additional cost to the University. All unused duct shall have a nylon or polypropylene pull string installed for future use. The pull-string shall be Greenlee or equal with a minimum of 240 lbs. tensile strength, and shall be rot and mildew resistant. Two feet of excess length shall be coiled inside the duct at each end. Spare duct(s) shall be capped or plugged at each end. Wire shall not be used. A red warning tape that is a minimum of 6 wide shall be installed 18 above all duct banks. Duct bank penetrations into manholes shall continue completely through the wall of the manhole and shall use one larger hole rather than several small holes. If above method is not practical, the concrete may stop outside the manhole but must be pinned to the manhole with steel pins to prevent differential settlement. Duct bank penetrations of foundation wall shall comply with the following: Concrete encased duct banks shall terminate at the exterior surface of the foundation wall. The conduit shall make individual penetrations of the foundation wall. All duct banks shall be attached to the foundation wall in one of two manners. In new construction, the reinforcing steel of the foundation wall may be extended into the concrete encasement of the duct bank at the time of placement. Alternately, reinforcing steel may be drilled into the foundation wall and extended into the duct bank concrete. The steel that is inserted into the foundation wall shall be attached through the use of epoxy capsules, similar to those supplied by Hilti. The conduit shall penetrate the foundation wall in the following manner: UPDATED NOVEMBER 27, 2017 Page 4 of 5

5 For existing construction, the hole shall be core drilled. In multiple duct situations, sufficient space shall remain between the penetrations to maintain the structural integrity of the foundation wall. CONCRETE Concrete shall be 3,000 psi and shall have the color additive MOUNTAIN RED. The color additive shall have a minimum concentration of 9 lbs. per yard of cement and shall be mixed throughout all of the duct bank concrete. Maximum aggregate size shall be 3/4. Concrete shall NOT be placed with the aid of a mechanical vibrator. If trench erosion occurs, use of forms may be required to prevent overly large masses of concrete. CERTIFIED SAFETY PROFESSIONAL ALL electrical work involving existing or new 15kV distribution shall be specified to include a CERTIFIED SAFETY PROFESSIONAL (CSP). The CSP must be present and approve on site all work on or in close proximity to energized circuits, switches or equipment. The CSP will be responsible for all activities onsite but must be present for any and all work on or near energized circuits. The CSP shall be the safety and occupational health competent person as defined in the Contractors Safety Plan. The CSP shall have not other duties than safety & occupational health management and inspections. MANHOLE FEATURES Manholes to be 96 x 96 x 96, reinforced concrete (pre-cast acceptable). Manhole shall have 36 diameter steel cover rated for deliberate vehicular traffic, H20 structural loading, marked ELECTRICAL on cover. Install cable racks. Four ground rods one each corner. UPDATED NOVEMBER 27, 2017 Page 5 of 5