Specifications.docx

Narrows Dam GSU Transformer Supply P&S NRTS15

SECTION 48 19 23.01

8,400/12,000 KVA CLASS I GSU POWER TRANSFORMERS

PART 1 GENERAL

1.1 DESCRIPTION OF WORK

This Section covers the design, manufacturing and factory testing of four single-phase generator step-up (GSU) power transformers rated 8,400/12,000 kVA, 69 kV GrdY/39.8 kV high-voltage, 13.2 kV low-voltage, Class OFAF/OFAF cooling, for delivery f.o.b. to Narrows Dam switchyard. Transformer shipment, hauling, off-loading and placement in the operating location, site reassembly and field testing requirements are as required in SECTION 48 20 00. Throughout this Section, the transformer tank layout is identified by Segments 1 through 4, as defined in IEEE C57.12.10, Figure 1, and indicated on drawings E-101 and E-102.

1.2 GENERAL ARRANGEMENT AND CONNECTED POWERTRAIN

1.2.1 General Arrangement

The transformers specified in this Section will replace four existing single-phase transformers presently located in the Narrows Dam switchyard. Reference drawing 329/93451, Sheet 151, shows the layout and configuration of the existing transformers. The new single-phase transformers shall be designed and manufactured as required herein, for installation in the same location as the existing transformers. One single-phase transformer will be installed as a spare. Anchoring of each transformer and all external connections to power plant equipment will be performed by a separate installations contractor.

1.2.2 Connected Powertrain

The new single-phase transformers shall be sized per the requirements of paragraph, "Ratings and Electrical Characteristics". The bank of single-phase transformers will transmit the power of three connected hydrogenerators rated 10,860 kVA, 0.90 pf.

1.3 REFERENCED PUBLICATIONS

The publications listed below form a part of this specification to the extent referenced. The publications are referred to within the text by the basic designation only.

AMERICAN SOCIETY FOR NONDESTRUCTIVE TESTING (ASNT)

ASNT SNT-TC-1A (2011) Recommended Practice for Personal Qualification and Certification in Nondestructive Testing

ASME INTERNATIONAL (ASME)

ASME B1.1 (2003; R 2008) Unified Inch Screw Threads (UN and UNR Thread Form)

ASME B1.20.1 (2013) Pipe Threads, General Purpose (Inch)

ASME B16.1 (2010) Gray Iron Pipe Flanges and Flanged Fittings (Classes 25, 125, and 250)

ASME B16.24 (2011) Cast Copper Alloy Pipe Flanges and Flanged Fittings (Classes 150, 300, 600, 900, 1500, and 2500

ASME B18.2.6M (2012) Metric Fasteners for Use in Structural Applications

ASME BPVC SECTION IX (2013) Qualification Standard for Welding and Brazing Procedures, Welders, Brazers, and Welding and Brazing Operators

ASTM INTERNATIONAL (ASTM)

ASTM A 53 (2012) Standard Specification for Pipe, Steel, Black and Hot-Dipped, Zinc-Coated, Welded and Seamless

ASTM A 343 (2014) Standard Test Method for Alternating-Current Magnetic Properties of Materials at Power Frequencies Using Wattmeter-Ammeter-Voltmeter Method and 25-cm Epstein Test Frame

ASTM A 475 (2003; R 2014) Standard Specification for Zinc-Coated Steel Wire Strand

ASTM A 664 (2015) Standard Practice for Identification of Standard Electrical Steel Grades in ASTM Specifications

ASTM A 717 (2012) Standard Test Method for Surface Insulation Resistivity of Single-Strip Specimens

ASTM A 876 (2012) Standard Specification for Flat-Rolled, Grain-Oriented, Silicon-Iron, Electrical Steel, Fully Processed Types

ASTM D 923 (2015) Standard Practice for Sampling Electrical Insulating Liquids

ASTM D 1533 (2012) Standard Test Method for Water in Insulating Liquids by Coulometric Karl Fischer Titration

ASTM D 1535 (2014) Standard Practice for Specifying Color by the Munsell System

ASTM D 3487 (2009) Standard Specification for Mineral Insulating Oil Used in Electrical Apparatus

ASTM D 4059 (2000; R 2010) Standard Test Method for Analysis of Polychlorinated Biphenyls in Insulating Liquids by Gas Chromatography

ASTM F 1145 (2005; R 2011) Standard Specification for Turnbuckles, Swaged, Welded, Forged

AMERICAN SOCIETY OF CIVIL ENGINEERS (ASCE)

ASCE 7-10 (2010) Minimum Design Loads for Buildings and Other Structures

AMERICAN WELDING SOCIETY (AWS)

AWS A2.4 (2012) Standard Symbols for Welding, Brazing, and Nondestructive Examination

AWS D1.1 (2015) Structural Welding Code - Steel

AWS D1.6 (2007) Structural Welding Code - Stainless Steel

INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)

IEEE 693 (2005) Recommended Practice for Seismic Design of Substations

IEEE C57.12.00 (2010) General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers

IEEE C57.12.10 (2010; Corr 2 - 2013) Requirements for Liquid-Immersed Power Transformers

IEEE C57.12.70 (2011) Standard Terminal Markings and Connections for Distribution and Power Transformers

IEEE C57.12.80 (2010) Terminology for Power and Distribution Transformers

IEEE C57.12.90 (2010) Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers

IEEE C57.13 (2008) Requirements for Instrument Transformers

IEEE C57.19.00 (2004; ERTA 2010) General Requirements and Test Procedures for Outdoor Power Apparatus Bushings

IEEE C57.19.01 (2000; R 2010) Performance Characteristics and Dimensions for Outdoor Apparatus Bushings

IEEE C57.91 (2011) Guide for Loading Mineral-Oil-Immersed Transformers and Step-Voltage Regulators

IEEE C57.104 (2008) Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers

IEEE C57.113 (2010) Recommended Practice for Partial Discharge Measurement in Liquid-Filled Power Transformers and Shunt Reactors

IEEE C57.149 (2012) Guide for the Application and Interpretation of Frequency Response Analysis for Oil-Immersed Transformers

MANUFACTURERS STANDARDIZATION SOCIETY OF THE VALVE AND FITTINGS INDUSTRY (MSS)

MSS SP-72A (2010) Ball Valves with Flanged or Butt-Welding Ends for General Service

NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)

NEMA 250 (2014) Enclosures for Electrical Equipment (1000 Volts Maximum)

NEMA C80.1 (2015) Electrical Rigid Steel Conduit (ERSC)

NEMA FB 1 (2014) Fittings, Cast Metal Boxes, and Conduit Bodies for Conduit, Electrical Metallic Tubing, and Cable

NEMA ICS 1 (2000; R 2015) Industrial Control and Systems General Requirements

NEMA ICS 2 (2000; R 2005) Industrial Control and Systems Controllers, Contactors, and Overload Relays Rated 600 Volts

NEMA ICS 5 (2000; R 2010) Control Circuit and Pilot Devices

NEMA MW 1000 (2015) Magnet Wire

NEMA SG 4 (2009; R 2013) Alternating-Current High-Voltage Circuit Breakers

NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)

NFPA 70 (2014) National Electrical Code

NFPA 110 (2016) Standard for Emergency and Standby Power Systems

UNDERWRITERS LABORATORIES (UL)

UL 1008 (2014; Rev thru Oct 2015) Transfer Switch Equipment

UL 248-8 (2011; Rev thru Aug 2015) Low-Voltage Fuses - Part 8: Class J Fuses

UL 360 (2013; Rev thru Jan 2015) Liquid-Tight Flexible Metal Conduit

UL 489 (2013; Rev thru Mar 2014) Molded-Case Circuit Breakers, Molded-Case Switches and Circuit-Breaker Enclosures

UL 508 (1999; Rev thru Oct 2013) Industrial Control Equipment

UL 508A (2013; Rev thru Jan 2014) Industrial Control Panels

UL 514B (2012; Rev thru Nov 2014) Conduit, Tubing, and Cable Fittings

UL 969 (1995; Rev thru Sep 2014) Safety Marking and Labeling Systems

UL 4248-8 (2007; Rev thru Oct 2013) Fuseholders - Part 8: Class J

U.S. ARMY CORPS OF ENGINEERS (USACE)

EM 385-1-1 (2008; Eratta Jul 2011) Safety and Health Requirements Manual

1.4 SUBMITTALS

Government approval is required for submittals with a "G" designation; submittals not having a "G" designation are for information only or as otherwise designated. When used, a designation following the "G" designation identifies the office that will review the submittal for the Government. The following shall be submitted in accordance with SECTION 01 33 00, "SUBMITTAL PROCEDURES", unless otherwise indicated below:

SD-02 Shop Drawings

a. Outline and Assembly Drawings; G, HDC

Outline and assembly drawings of the transformers shall be submitted for approval within 150 calendar days after date of award to demonstrate that the equipment will conform to the requirements and intent of the specifications.

b. Detail Drawings; G, HDC

Detail drawings shall be submitted for approval within 210 calendar days after date of award to demonstrate that the equipment will conform to the requirements of the specifications.

SD-05 Design Data

a. Descriptive Data; G, HDC

Descriptive data or catalog data of all accessory devices and ancillary equipment provided with the transformers shall be submitted for approval within 240 calendar days after date of award, to demonstrate fully that all parts of the equipment will conform to the requirements and intent of the specifications.

b. Spare Parts List; G, HDC

A listing of all required spare parts to be provided with the transformers shall be submitted for approval within 240 calendar days after date of award. (see paragraph "SPARE PARTS")

c. Structural Design Criteria and Seismic Calculations; G, HDC

Structural design criteria and seismic calculations shall be submitted for approval within 210 calendar days after date of award. Design criteria and calculations shall be performed by qualified civil or structural engineers who are presently registered professional engineers (PE). A cover sheet for the submittal shall be provided and stamped or sealed and signed by a PE.

d. Electronic Temperature Monitor Settings and Software Configuration; G, HDC

Electronic Temperature Monitor Settings and Software Configuration data shall be submitted for approval a minimum of 60 calendar days prior to the performance of the factory acceptance tests. (see paragraph "Electronic Temperature Monitor with Fiber Optic Winding Temperature Measurement").

SD-06 Test Reports

a. Transformer Factory Acceptance Test Report; G, HDC

The transformer factory acceptance test report shall be submitted for approval not later than 14 calendar days following completion of the factory acceptance tests for each transformer. (see paragraph "Factory Acceptance Test Report").

b. Bushing Design Tests; G, HDC

The transformer bushing design test reports shall be submitted for approval not later than 30 calendar days following completion of the tests (see paragraph "Bushing Design Tests"). If certified copies of bushing design tests previously conducted within five (5) years are submitted in-lieu of new test results, they shall be submitted when the bushing selection is made, but not later than 60 calendar days prior to the performance of transformer factory acceptance tests.

c. Bushing Routine Tests; G, HDC

The transformer bushing routine test reports shall be submitted for approval not later than 30 calendar days following completion of the tests. (see paragraph "Bushing Routine Tests").

d. Bushing Current Transformer Tests; G, HDC

The transformer bushing current transformer test reports shall be submitted for approval not later than 30 calendar days following completion of the tests. (see paragraph "Bushing Current Transformer Tests").

SD-07 Certificates

a. Transformer Oil Certification; G, HDC

Transformer oil certification shall be submitted for approval a minimum of 14 calendar days prior to the delivery of oil for each transformer to the Narrows Dam power plant. (see paragraph "Quantity and Transformer Oil Certification").

b. Notification of the Date of the Transformer Design Review Meeting; G, HDC

The contractor shall notify the COR 30 calendar days in advance of when the transformer manufacturer will be ready for performance of a design review meeting, to be held at the manufacturer's facility. (see paragraph "TRANSFORMER DESIGN REVIEW MEETING").

c. Notification of the Date of Factory Tests; G, HDC

The contractor shall notify the COR, in writing, 30 calendar days in advance of when the transformer will be ready for factory acceptance tests, so that the tests may be witnessed by a Government Representative. If factory testing in a foreign country is proposed, the Contractor shall notify the COR in writing of the preliminary testing dates, not later than 60 days prior to the start of factory tests. (see paragraph "TRANSFORMER FACTORY ACCEPTANCE TESTS").

d. Welder Qualifications; G, HDC

The welding operators and welders qualifications shall be submitted a minimum of 30 calendar days prior to their performance of work. (see paragraph "Welder Qualifications").

e. Weld Inspector Qualifications; G, HDC

The qualifications for the Contractor's Quality Assurance personnel responsible for performing weld inspections shall be submitted a minimum of 30 calendar days prior to the performance of weld inspections. (see paragraph "Inspection and Weld Inspector Qualifications").

SD-08 Manufacturer's Instructions

a. Factory Test Procedures; G, HDC

The transformer factory test procedures shall be submitted for approval a minimum of 60 calendar days prior to the performance of the factory acceptance tests for the first transformer. (see paragraph "TRANSFORMER FACTORY ACCEPTANCE TESTS").

b. Welding Procedures; G, HDC

Welding procedures and specifications and copies of test reports shall be submitted a minimum of 30 calendar days prior to the performance of work. (see paragraph "Welding Procedure").

c. Prequalified Weld Procedures; G, HDC

Applicable prequalified weld procedures per the requirements of AWS shall be submitted a minimum of 30 calendar days prior to the performance of work. (see paragraph "Welding Procedure").

1.5 WARRANTY REQUIREMENTS

In addition to the requirements outlined in FAR 52.246-17, the manufacturer’s warranty for the power transformers shall continue for a period of five (5) years from the date of final acceptance of the work. If the Government takes possession of any part of this work before final acceptance, this warranty shall continue for a period of five (5) years from the date the Government takes possession. The following transformer issues will also be considered warranty repair items:

a. Transformer gassing rates beyond the Condition 1 level as defined in Tables 2 and 3 of IEEE C57.104, or concentrations exceeding the Condition 1 limits as defined in Table 1 of IEEE C57.104

b. Transformer oil leaks.

PART 2 PRODUCTS

2.1 TYPE AND RATING

2.1.1 General

The transformers furnished under these specifications shall be single-phase, two-winding, with one high-voltage and one low-voltage winding, oil-immersed type suitable for outdoor operation. The transformers shall be forced oil-cooled/forced air-cooled type, Class OFAF/OFAF, and shall be of a design that has an established record of satisfactory operation with the type of oil preservation system specified. The transformers shall be designed and manufactured for transportation by rail and trucking by heavy hauler, and for shipment by sea if the transformers have a probability of being transported by this method.

2.1.2 Transformer Limiting Dimensions and Equipment Arrangement

The transformers' design, configuration, and dimensions shall be as indicated on the contract drawings, and the transformers shall not exceed the limiting dimensions.

2.1.3 Requirements

Except as otherwise specified herein, the transformers, accessories, and spare parts shall conform to the applicable requirements of IEEE C57.12.00, IEEE C57.12.10, IEEE C57.12.70, IEEE C57.12.80 and IEEE C57.12.90.

2.1.4 Standard Products

Material and equipment provided with each transformer shall be standard products from a manufacturer regularly engaged in their production, and shall essentially duplicate items that have been in satisfactory use for at least 3 years prior to bid opening, unless otherwise specifically approved. All materials shall conform to the requirements of these specifications. Descriptive data, including catalog data of all accessory devices, ancillary equipment, and gaskets to be provided with the transformers shall be submitted for approval. Materials shall be of industrial quality, free from defects and imperfections, of recent manufacture, and of the classification and grades designated. All materials, supplies, and articles not manufactured by the Contractor shall be the products of other recognized reputable manufacturers. If the Contractor desires for any reason to deviate from the standards designated in these specifications, a statement shall be submitted for approval describing the exact nature of the deviation, including complete specifications for the materials that are being proposed for use.

2.1.5 Ratings and Electrical Characteristics

The ratings and electrical characteristics of each transformer shall be as follows:

a. Continuous ratings, at the 65 degrees-C temperature rated temperature rise, on all taps, kVA:

(1) OFAF Rating (one cooling group in operation): 8,400

(2) OFAF Rating (two cooling groups in operation): 12,000

b. Frequency, Hz: 60

c. Number of phases: 1

d. Rated voltage, kV:

(1) High-voltage windings: 69 kV Grd. Y/39.8 kV

(2) Low-voltage windings: 13.2

e. Winding connections (external to the transformer):

(1) High-voltage windings: Grounded-Wye

(2) Low-voltage windings: Delta

f. Impedance, at maximum OFAF rated current, subject to IEEE tolerances, percent: 10.0

g. Polarity: Subtractive

h. Basic impulse insulation levels (BIL), kV:

(1) Line ends of the high-voltage windings, not less than: 350

(2) Neutral ends of the high-voltage windings, not less than: 150

(3) Low-voltage windings, not less than: 110

i. Taps in low voltage windings: None

j. Taps (full capacity) in high voltage winding

(1) Tap 1, percent of high-voltage rating: 105.0

(2) Tap 2, percent of high-voltage rating: 102.5

(3) Tap 3, percent of high-voltage rating: 100.0

(4) Tap 4, percent of high-voltage rating: 97.5

(5) Tap 5, percent of high-voltage rating: 95.0

k. Maximum no-load losses at rated voltage and frequency, kW: 17

l. Maximum load losses at maximum OFAF rated kVA and 1.0 power factor, kW: 50

m. Maximum average sound level at rated voltage and frequency, with all cooling groups in operation, dB: 72

n. Maximum transformer total weight, completely assembled and oil filled with all accessories installed, pounds: 60,000

2.1.6 Unusual Service Conditions

Each transformer will be subject to the following unusual service conditions, as defined by IEEE C57.12.00, paragraph 4:

The impedance tolerance of each transformer shall be limited to a maximum of 3 percent from the specified impedance, at the maximum OFAF rating, to reduce circulating currents when wye-connected and assure proper operation of the transformer differential relaying.

2.2 STRUCTURAL DESIGN CRITERIA AND SEISMIC CALCULATIONS

Structural design criteria and seismic calculations shall be provided for the transformer design, to include the main tank and all major components such as bushings, cooling equipment and cabinets.

2.2.1 Structural Design Criteria

Structural design criteria shall include the following:

a. Indicate the industry design standards and allowable stresses or capacities to which steel plate, structural steel shapes, welds, bolts and studs shall conform.

b. Indicate the industry standards used in developing the seismic forces and analysis techniques used in design of the transformers and transformer components.

c. Seismic design for equipment restraint shall be in accordance with Chapter 13, "Seismic Design Requirements for Nonstructural Components," of ASCE 7-10 with the seismic design force computed as per Section 13.3 "Seismic Demands on Nonstructural Components". Electrical equipment restraint shall designed in accordance with the provisions in IEEE 693 Annex D, or Section 13.3 of ASCE 7-10 whichever produces the more adverse seismic effects. For ASCE 7-10, use a spectral acceleration SDS = 0.105, IP = 1.50, and z=h=1. For IEEE 693, the seismic qualification level shall be moderate.

2.2.2 Seismic Calculations

Seismic calculations shall include the following:

a. Derivation of seismic forces and load cases. Load cases used for developing seismic anchorage of the complete transformer shall account for the effect of the righting force of the weight of the transformer.

b. Calculations for use in the design of anchorage to resist overturning and base shear. The maximum uplift and shear force per anchor shall be provided in pounds or kips.

c. A schematic depicting the location of the center of gravity, the applied seismic forces relative to the base, and the location of seismic anchors.

d. Calculations for individual components and their attachment to the transformers.

2.2.3 Anchorage to Concrete Pad for Seismic Restraint

Each transformer shall be designed for mounting on a structural steel platform which will be installed on the existing concrete pedestals. Removal of the rail on the existing pedestals, and manufacturing and installation of the structural steel platform on the concrete pedestals will be performed by others under separate contract. For purposes of performing seismic calculations, each transformer's base will be welded to the steel platform as indicated in paragraph, Structural Steel Supporting Base.

2.3 THERMAL DESIGN

The temperature rise above ambient temperature of each transformer or parts thereof, when tested in accordance with its ratings, shall not exceed the limits of observable temperature rise for oil immersed apparatus as stated in IEEE C57.12.00 (paragraph 5.11.1). The winding temperature rise by resistance shall not exceed 65 degrees-C, and the hottest spot winding temperature rise shall not exceed 80 degrees-C on the tap connections that give the highest losses, with all coolers in operation. In addition, each transformer shall not exceed the above temperature rises when tested at the first stage OFAF kVA rating with one cooling group in operation.

2.4 CORE

Each transformer core shall be constructed of high-quality, non-aging, cold-rolled, grain-oriented steel especially suitable for the purpose. The core steel laminations shall meet the requirements of ASTM A 664 and ASTM A 876, shall have a maximum thickness of 0.270 mm, and the design flux density shall not exceed 1.75 Tesla. The use of paper insulation in the core will not be acceptable. Electrical core steel core loss, rms exciting power, rms and peak exciting current, and ac permeability shall be tested in accordance with ASTM A 343. Each roll of sheet steel used shall have the surface insulation resistivity tested in accordance with ASTM A 717. The core shall be carefully assembled and rigidly clamped to ensure adequate mechanical strength to support the windings and to prevent shifting of the laminations during shipment, and also to reduce vibration to a minimum under operating conditions. Core joints shall be interleaved. The transformer core design and construction methods shall be in such a manner to assure that the average sound level due to operation of each transformer and accessories will not exceed 72 dB at rated voltage and frequency as measured in accordance with IEEE C57.12.90.

2.5 WINDINGS

2.5.1 General

Each transformer shall be manufactured with windings meeting the requirements of paragraph "Ratings and Electrical Characteristics", consisting of one high-voltage winding (H) and one kV low-voltage winding (X). The winding conductors shall be of high-conductivity copper magnet wire meeting the applicable requirements of NEMA MW 1000, and if of a core-form design shall be of a circular coil construction. Conductor insulation shall consist of thermally upgraded Kraft paper. Consideration shall be given to all factors of service, such as high dielectric and mechanical strength of insulation, coil characteristics, and minimum restrictions to free circulation of oil. Coils shall be made up, shaped, and braced to provide for expansion, contraction, and shrinkage due to temperature changes and aging in service in order to avoid abrasion of insulation and to provide resistance to movement and distortion caused by abnormal operating conditions. Adequate barriers shall be provided between windings and core and between high-voltage and low-voltage windings. End coils shall have additional protection, if required, against normal line disturbances. A de-energized tap changer shall be provided, with taps located in the high-voltage windings. The tap changer contacts shall be silvered, and capable of withstanding the full short circuit current of the transformer without injury.

2.5.2 Insulation Levels

The transformers shall be designed for BIL of the windings as specified in paragraph "Ratings and Electrical Characteristics", and shall be capable of withstanding IEEE Standard dielectric tests, in accordance with paragraph "Power Transformer Tests", corresponding to the specified winding insulation levels.

2.5.3 Short Circuit Capability

The transformers shall be capable of withstanding without injury the mechanical and thermal stresses caused by short circuits on the external terminals of any winding or windings, with rated voltages maintained across the terminals of all other windings intended for connection to sources of energy, under the conditions listed in IEEE C57.12.00 (paragraph 7.1.1).

2.5.4 Embedded Fiber Optic Probes

Fiber optic probes used for direct winding temperature measurement shall be embedded in the high and low voltage windings. Quantities and distribution shall be as indicated in paragraph "Electronic Temperature Monitor with Fiber Optic Winding Temperature Measurement". Probes shall be embedded in the calculated hottest spot for each winding.

2.6 TANK

2.6.1 Construction

Each transformer shall be provided with an oil-tight steel tank, with oil-tight covers per the requirements of IEEE C57.12.10 (paragraph 5.8). Each tank shall be provided with one or more unobstructed manholes in the cover with minimum dimensions of 24 inches by 24 inches, or 24 inches minimum diameter, to afford easy access to the lower ends of bushings, terminals, and the upper portions of the coils. Suitable positioning guides shall be provided inside the tank to assure the core and windings are in the correct position during assembly. The main transformer tank and any attached compartment that is subjected to operating pressures shall be designed and constructed to withstand, without leakage or permanent deformation, an internal pressure not less than 10 psi. The tank shall be designed and constructed for vacuum filling (essentially full vacuum) in the field. All valves, fittings and piping affected by vacuum filling shall be of correct design and construction for such filling. Auxiliary compartments such as reservoir tanks, when not designed for vacuum filling, shall be so designated, and suitable isolating valves shall be provided. The joints between the tank and cover, and between tank sections shall be welded, and the design of the joint shall prevent weld splatter from entering the inside of the tank.

2.6.2 Gasketing

Gaskets between metal surfaces shall be set in expansion-limiting grooves or held in position by retainers so arranged that all contact surfaces are metal-to-metal when tightened. The gaskets shall be made of Nitrile NBR (Buna N) with a Durometer rating between 50 and 60. Gaskets shall be designed for compression by at least 25% of their original thickness. O-ring Gaskets shall not be used for gasket grooves of rectangular cross-section.

2.6.3 Lifting and Moving Facilities

2.6.3.1 Lifting Facilities

Design loads for lifting eyes, lugs or hooks shall be two times the actual load to allow for possible unequal lifting forces, with a safety factor (using design loads) in accordance with IEEE C57.12.10 (paragraph 5.3.1). Lifting eyes, lugs, or hooks shall positively keep the lifting cable in place even when the cable is slack. Each transformer shall be provided with the following lifting facilities:

a. Lifting attachments on the tank cover.

b. Adequate means for lifting the core and coil assembly from the tank.

c. Lifting eyes on the tank, adequate for lifting the complete transformer filled with oil, and located at the top of the tank sidewalls for a transformer of core-form design. The placement of the lifting eyes shall be designed to allow for lashing of the transformer during shipment.

2.6.3.2 Moving Facilities

Moving features shall be furnished as required for moving each transformer to its final location as shown, and shall be in accordance with IEEE C57.12.10 (paragraph 5.3.3).

2.6.4 Valves

Each transformer shall be provided with valves conforming with IEEE C57.12.10 (paragraph 5.1.8), unless otherwise specified, below. All valves, shall be of stainless steel construction conforming to MSS SP-72A, circular flanged, reinforced PTFE valve seats, and shall be ball-type unless otherwise specifically indicated. The valves shall be of full-port design, when available, designed for use with insulating oil, have a 120 degrees Celsius minimum temperature rating, and shall be include provisions for locking of the handle. Valve handles shall be of a circular, or oval, design. Weather resistant locks shall be provided for all valves, keyed the same. Valves shall be provided for the following:

a. Upper filter connection. A 2-inch valve shall be located on the Segment 4 tank sidewall such that it can be used to fill the transformer with oil while the transformer is under vacuum. The outbound connection shall be a 2-inch female NPT thread, provided with a threaded plug.

b. Vacuum pump connection. A 3-inch valve shall be located on the tank cover for use in connecting a vacuum pump during the vacuum filling process. The outbound valve connection shall be a circular 4-bolt flanged, provided with a gasketed blind flange cover with an integral 3-inch NPT female connection with threaded plug.

c. Main drain. A 3-inch valve shall be located at the extreme bottom of the tank on Segment 4 tank sidewall for use in gravity draining of the transformer. The outbound valve connection shall be circular 4-bolt flanged, provided with a gasketed blind flange cover with an integral 3-inch NPT female connection with threaded plug.

d. Oil sampling valve. A sampling valve shall be located at the bottom of the tank on the Segment 2 tank sidewall with a 1/2-inch NPT threaded discharge end. This valve may be integral to the lower filter valve. A 1/2-inch threaded sampling device, complete with protective cover shall be provided for the purposes of obtaining oil samples, and shall be a United Brass Works Model 86, or approved equal.

e. Lower filter connection. A 2-inch valve shall be located at the bottom of the tank on the Segment 2 tank sidewall. The outbound connection shall be a 2-inch female NPT thread, provided with a threaded plug.

f. Tank air vents. Valves shall be provided for venting of the bushing turrets.

g. Isolation valves. The following isolation valves shall be provided:

(1) Electronic Pressure Monitor Transducers. Isolating the electronic pressure monitor transducers. The outbound valve connection shall be circular 4-bolt flanged, and sized to match the bolt pattern of the electronic pressure monitor transducer's manifold.

(2) Oil Circulating Pumps. At the inlet and outlet of each oil circulating pump to permit pump isolation for maintenance purposes without draining the oil from the tank. Pump isolation valves may be of a butterfly design, and may be of steel construction with a corrosion resistant paint.

(3) Coolers. At the inlet and outlet of each cooler to permit removal without draining the oil from the tank. Cooler isolation valves at may be of a butterfly design, and may be of steel construction with a corrosion resistant paint.

(4) Radiators. At the inlet and outlet of each radiator to permit removal without draining the oil from the tank. Radiator isolation valves at the transformer tank may be of a butterfly design, and may be of steel with a corrosion resistant paint.

(4) On-line dissolved gas-in-oil monitor. Two 1.5-inch valves shall be provided on the Segment 3 tank sidewall for connection to the on-line dissolved multi-gas and moisture content monitor. The outbound connections shall be a 1.5-inch female NPT thread, provided with a threaded plug.

2.6.5 Connections

2.6.5.1 General

All bolts, studs, machine screws, nuts, and tapped holes designed for customer connection shall be in accordance with ASME B1.1 (inch fasteners), or ASME B18.2.6M (metric fasteners). Bolting hardware shall be Grade 5 minimum, or equivalent, and and all hardware not internal to the tank shall be galvanized. Threads for sizes 1/4-inch to 1-inch, inclusive, shall be NC or UN series. The sizes and threads of all valves, pipe and fittings, conduit and fittings, tubing and fittings, and connecting equipment, shall be in accordance with ASME B1.20.1. Manufacturers' standard threads and construction may be used on small items which are integrally replaceable, except that threads for external connections to these items shall meet the above requirements.

2.6.5.2 Stainless Steel

All stainless steel connecting hardware shall be installed using an anti-galling compound such as molybdenum disulfide on the threads prior to connection.

2.6.6 Steel Pipe and Fittings

Steel pipe shall conform to ASTM A 53, Weight A, Class 2. Dimensions of terminating flanges shall conform to ASME B16.1 and ASME B16.24.

2.6.7 Grounding

Four ground pads shall be provided on each transformer for grounding the tank and base. The grounding provisions shall be in accordance with IEEE C57.12.10 (paragraph 5.5).

2.6.8 Personal Fall Protection System

A fall protection system, consisting of removable safety posts and wire rope railing shall be provided for each transformer. The post and railing system shall be designed such the components can be installed with, or without, the low-voltage bus connections in-place. A storage cabinet shall be provided for the fall protection system components, which will be mounted remote from each transformer, by others. The cabinet shall have a structural steel frame with provisions for anchoring to a concrete wall, shall have hinged doors with handles meeting the same requirements as the control cabinet, and be painted to match the transformer. The fall protection system shall be designed to meet the applicable provisions of EM 385-1-1, Section 21, and meet the following requirements:

a. Post holders shall be welded around the perimeter of the transformer tank top cover, shall have provisions for draining standing water, and include holes for the installation of securing pins which align with holes in the posts.

b. The posts shall be made of powdercoated yellow aluminum 2-1/2 inch Schedule 80 pipe a minimum of 48-inches tall, spaced a maximum of 6-feet apart, and shall have looped-guides for the positioning of each wire rope rail. The looped guides shall be sufficiently sized to allow for routing of the wire rope railing during installation.

c. Two wire rope rails shall be provided (a toprail and a midrail). The toprail wire rope shall be positioned 42-inches above the transformer top cover, and the midrail wire rope shall be positioned 21-inches above the transformer top cover.

d. Each rail shall consist of a 5/16-inch 7x19 stranded core, galvanized-steel wire rope with a red vinyl-coating, meeting the requirements of ASTM A 475. Each wire rope shall be constructed with a swage clevis fitting on one end and a swage eye fitting on the other end. The clevis fitting end shall be designed to connect to a post looped guide, and the eye fitting shall be designed to connect to the jaw-end of a turnbuckle. The wire rope shall be designed so that when fully assembled and tensioned with the tensioning hardware, a maximum 3-inch rope deflection may be achieved under a 200 pound applied force.

e. One forged galvanized steel turnbuckle, with an open body jaw end design and 800 pound minimum working load limit, shall be provided with each wire rope for tensioning purposes. The turnbuckle jaw ends shall be sized for connection to the wire rope swage eye fitting and the post looped guides. The turnbuckle shall meet all applicable requirements of ASTM F 1145, Type 1, Grade 1.

2.6.9 Portable Fall Arrest System

2.6.9.1 Portable Fall Arrest System Anchor Post

One portable fall arrest system anchor post shall be provided, designed for attachment to the mounting plates, indicated below. The anchor post shall be as manufactured by Western Safety Products, Model 16691, or approved equal, and have the following features:

a. Three-stage, four-position telescoping design of aluminum construction.

b. Provision of three independent swivel tie-off points, with horizontal lifeline attachment.

c. Base leveling screws allowing the system to be plumbed to vertical for working stability on inclines up to 15-degrees.

d. Designed for attachment to a uni-anchor mounting plate.

2.6.9.2 Anchor Post Accessories

The following accessories shall be provided with the portable fall arrest system anchor post:

a. Rescue Davit Arm, with quick mount winch and cable.

b. Carrying bag for the anchor post assembly.

c. Carrying bag for the Davit Arm with mounted winch.

2.6.9.3 Mounting Plates

A minimum of one portable fall arrest system anchor post mounting plate shall be provided on each transformer cover. Sufficient mounting plates shall be provided so that each transformer cover manhole access is within 24 inches of a mounting plate. Each mounting plate shall be welded onto the tank cover, and shall be a Uni-Anchor Plate and Lug, Model 17412, or approved equal, designed for use with the portable fall arrest system anchor post, indicated above.

2.6.10 Oil Level Markings

The 25 degrees-C oil level shall be indicated on the outside of the Segment 3 tank sidewall by suitable permanent markings, and the change in oil level per 10 degrees-C change in oil temperature shall be indicated on each transformer nameplate.

2.6.11 Structural Steel Supporting Base

Each transformer shall be provided with an integral structural steel supporting base designed for pad mounting, of 6 inches thickness. The integral steel supporting base shall include two skid channels oriented perpendicular to the Segment 1 and 3 tank sidewalls, and two skid channels oriented perpendicular to the Segment 2 and 4 tank sidewalls. The outboard ends of these skid channels will be welded to a structural steel platform anchored to the existing concrete pedestals, which will be provided by a separate installations contractor, after the transformer is placed into position. Welding of the transformer structural base skids to the steel platform on the concrete pedestals will be performed by others. The transformer steel supporting base shall be manufactured to withstand seismic forces as required in paragraph "STRUCTURAL DESIGN CRITERIA AND SEISMIC CALCULATIONS". Each transformer shall be designed to be suitable for moving on rollers or skids when completely assembled and filled with oil, and shall be designed to permit moving the transformer in a direction parallel to either centerline, with suitable pulling eyes provided.

2.6.12 Jack Ports

Each transformer base shall be provided with jack ports, bosses, or lugs, to permit jacking the complete transformer filled with oil per the requirements of IEEE C57.12.10 (paragraph 5.3.4). The design loads for jacking bosses or lugs shall be at least two times the actual loads to allow for possible unequal jacking forces.

2.6.13 Center of Gravity

Each transformer base shall be designed so that the center of gravity of the transformer, with or without oil as normally prepared for shipment, will not fall outside the base support members for a tilt of the base of 15 degrees from the horizontal.

2.7 COOLING EQUIPMENT

2.7.1 Radiators

Each transformer shall be provided with a sufficient number of ONAN radiators to cool the oil properly at a 333 kVA continuous load, without any additional OFAF cooling groups in operation, for powerhouse station service requirements. The radiators shall be located as indicated on the drawings, and so located on the tank to insure uniform circulation of the oil through the windings. The radiators shall be constructed of steel tubes or elements welded into steel headers. All welding shall be on the outside of the radiators such that there will be no crevices in which water might collect. The welding and fittings shall be smooth, both inside and out, so as to present no obstruction to the flow of oil inside. The radiators shall be fully hot-dip galvanized on the outside and remain unpainted. The radiators shall be designed to withstand essentially full vacuum to permit filling the transformer under vacuum with radiators in place and radiator valves open. Valves shall be installed on each connection to the main tank so that the radiators may be removed for repairs without taking the transformer out of service. Provisions shall be made for draining and venting the radiators, and lifting eyes shall be provided for handling.

2.7.2 Coolers

Each transformer shall have forced-oil, forced-air (OFAF/OFAF), cooling equipment of sufficient capacity to permit continuous operation of the transformer at the maximum rated kVA without exceeding the allowable temperature rise. The cooling equipment shall also be adequate to provide continuous operation at 70 percent rated load with one cooling group in service without exceeding the allowable temperature rise. The cooling equipment shall be provided in two separate cooling groups, which shall be mounted externally on the transformer tank, on the Segment 3 tank sidewall. Each cooling group shall include one or more suitable oil to air heat exchangers, one oil circulating pump, and adequate forced air equipment. The cooler enclosures and fan guards shall be of hot-dipped galvanized construction. The coolers shall be so located on the tank as to insure uniform circulation of the oil through the transformer windings. Valves in the oil inlet and outlet connections, and provisions for venting and draining, shall be provided on each cooler to permit the removal of any cooler without taking the transformer out of service.

2.7.3 Oil Circulating Pumps

The oil pumps and motors shall be designed to deliver the required amount of oil under the most adverse conditions, and the motors shall be of adequate size to drive the pumps continuously under such conditions without exceeding their kilowatt rating or rated temperature rise. Each motor shall be provided with thermal overload protection. Each pump shall be designed and connected so that it may be removed for repairs or replacement without taking the transformer out of service. The pumps shall have heavy-duty Class 30 cast iron casings, with the impellers designed to permit thermo-syphon flow when the pump is not operating. The pumps shall be rated for continuous operation for temperatures between -40C to 100 degrees Celsius. The motors shall be provided with large thrust face sleeve bearings, and shall be provided with thermal overload protection. A sight flow indicator and an oil flow switch with low flow alarm contacts shall be provided in the pipe connection to each oil pump as specified in paragraph "Oil Flow Indicators and Switches". The oil pumps shall be as manufactured by Cardinal, with the upgraded Harley sleeve bearings, or approved equal, and shall be located beneath the forced-air equipment as indicated.

2.7.4 Forced-Air Equipment

The forced-air equipment shall include propeller type fans with guards, and a rigid housing with venturi openings, and louvers or baffles, if needed, to direct the air stream against the heat exchangers and to prevent recirculation of discharged air. The propellers shall be balanced cast aluminum and shall provide adequate air delivery with low noise level. The fan motors shall be of splashproof or totally-enclosed construction suitable for continuous service and shall have individual thermal overload protection. The fan motors shall be provided with antifriction bearings having a L10 rating of 40,000 hours minimum. The transformer forced-air equipment shall be designed to assure that the average sound level due to operation of each transformer and accessories with all fans in operation will not exceed 72 dB, as measured in accordance with IEEE C57.12.90.

2.7.5 Power Supply Equipment

The power supply for the cooling fan motors and oil pumps will be Government-furnished, 208 V ac, three-wire, three-phase, 60 Hz, as indicated on the contract drawings. One three-pole, 600 V, molded case circuit breaker of proper current rating shall be provided in the power cabinet for the supply circuit.

2.7.6 Cooling Control Equipment

All necessary protective and control equipment for the coolers shall be furnished and installed in the transformer control and power cabinets for each transformer, and included in the controls of the electronic temperature monitor (see paragraph "CONTROL AND POWER CABINET EQUIPMENT").

2.8 BUSHINGS

2.8.1 General Bushing Requirements

Each transformer shall have one high-voltage, two low-voltage, and one neutral leads brought out from the tank through bushings as specified below. Bushings of the same voltage and current rating shall be interchangeable and, as applicable, conform to IEEE C57.19.00 and IEEE C57.19.01. All bushings shall meet the following requirements:

a. The bushings shall be designed for use in an air/oil transformer application, shall be oil-free, and constructed with a solid electrical-grade resin-impregnated paper (RIP) or resin-impregnated synthetic (RIS) capacitively-graded condenser core. Bushings of a RIP design shall be supplied with an air side composite insulator which consists of a fiber wound shell with high-temperature vulcanized (HTV) silicone rubber, with the edges of the insulator sheds having a low-stress teardrop tip with no visible parting lines. Bushings of a RIS design shall be supplied with an air side insulator with HTV silicone rubber adhered directly to the RIS condenser body, with the edges of the insulator sheds having a low-stress teardrop tip with no visible parting lines. The air end of the bushing insulators shall be light gray in color. The bushings shall be provided with a normally grounded test tap. The bushings shall be ABB Type CORIP, Type O Plus Dry, or approved equal.

b. Bushings shall be of recent manufacture and shall be of a type and style currently manufactured by the bushing manufacturer.

c. Bushings shall be nameplate rated and tested for use at 60 Hz rated frequency.

d. Bushings shall be designed for outdoor service. All bushings which will be exposed to direct sunlight shall have UV resistant insulating sheds.

e. Bushings shall be so designed that there will be no stressing of any parts due to temperature changes, and adequate means shall be provided to accommodate conductor expansion.

f. Bushings shall seal gastight and oiltight on the transformer tank as applicable.

2.8.2 Ratings

The bushings shall be designed to withstand the standard withstand test voltages as indicated in Table 1 of IEEE C57.19.01, for oil-impregnated bushings, and shall be tested in accordance with paragraph "Bushing Tests". The bushings shall be rated as follows:

2.8.2.1 High-Voltage Bushings

a. Insulation class, kV: 69

b. BIL rating, kV: 350

c. Minimum current rating, Amperes: 400

d. Creepage distance: Light contamination

2.8.2.2 High-Voltage Neutral Bushing

a. Insulation class, kV: 34.5

b. BIL rating, kV: 200

c. Minimum current rating, Amperes: 400

d. Creepage distance: Light contamination

2.8.2.3 Low-Voltage Bushings

a. Insulation class, kV: 25

b. BIL rating, kV: 150

c. Minimum current rating, Amperes: 1,200

2.8.3 High-Voltage and Neutral Bushing Terminals

The high-voltage and neutral bushings shall be provided with a threaded copper terminal stud with dimensions in compliance with IEEE C57.19.01. Each bushing shall be provided with an aluminum alloy bolted stud-to-cable terminal connector, sized for connection to a 350 kcMil bare stranded ACSR conductor. All contact surfaces of external terminals and of terminal connectors shall be silver-plated using pure silver free from copper.

2.8.4 Low-Voltage Bushing Terminal Connections

The low-voltage bushings shall be provided with a threaded copper terminal stud with dimensions in compliance with IEEE C57.19.01. Each low-voltage bushing shall be provided with a bronze alloy bolted stud-to-flat terminal connector, having a NEMA four-hole spacing. All contact surfaces of external terminals and of terminal connectors shall be silver-plated using pure silver free from copper.

2.8.5 Core Ground Bushings

Two external bushings for core grounding shall be provided; one for the main core ground, and one for the core frame ground. The bushings shall be manufactured with an integral cast copper stud, with an insulating body manufactured of either epoxy or solid porcelain. The stud shall be silver plated, and shall have have tapped holes for connection of removable grounding straps between the bushing terminal and the core and tank wall. The minimum ground wire size from each bushing terminal to the tank wall shall be #4 AWG equivalent. The bushings shall be mounted adjacent to each other, located on the transformer tank cover, protected with a removable weatherproof metal cover, and labeled to avoid confusion with other bushings. The core ground bushings shall have the minimum nameplate ratings:

a. Insulation class, kV: 2.5

b. BIL rating, kV: 45

c. Minimum current rating, Amperes: 100

2.8.6 SFRA Test Shipping Bushings

For the purposes of performing SFRA testing with the transformer in the shipping configuration, each shipping cover installed after the bushings have been removed for shipment shall include a bushing that is connected to the winding leads, so that the SFRA tests can be performed just prior to transformer shipment and immediately after transformer delivery to the Narrows Dam switchyard. This assembly shall permit the SFRA testing on the transformer without having to gain entrance into, or modifying the transformer shipping assembly. The winding leads shall be appropriately braced inside the transformer tank to assure there is no movement during shipment which could damage the bushings, or potentially alter the SFRA test results. During shipment, the external terminals of these bushings shall be grounded to the tank.