Atch_3_Specification_Section_26_12_19.10,_Three-Phase_Pad-Mounted_Transformers.pdf

SECTION 26 12 19.10

THREE-PHASE PAD-MOUNTED TRANSFORMERS

05/17

PART 1 GENERAL

1.1 REFERENCES

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

AMERICAN CONCRETE INSTITUTE INTERNATIONAL (ACI)

ACI 318 (2014; Errata 1-2 2014; Errata 3-5 2015;

Errata 6 2016; Errata 7 2017) Building Code Requirements for Structural Concrete and Commentary

ACI 318M (2014; ERTA 2015) Building Code Requirements for Structural Concrete & Commentary

AMERICAN NATIONAL STANDARDS INSTITUTE (ANSI)

ANSI C12.1 (2008) Electric Meters Code for Electricity Metering

ASTM INTERNATIONAL (ASTM)

ASTM A240/A240M (2016) Standard Specification for Chromium and Chromium-Nickel Stainless Steel Plate, Sheet, and Strip for Pressure Vessels and for General Applications

ASTM C260/C260M (2010a; R 2016) Standard Specification for Air-Entraining Admixtures for Concrete

ASTM D117 (2010) Standard Guide for Sampling, Test Methods, Specifications and Guide for Electrical Insulating Oils of Petroleum Origin

ASTM D1535 (2014) Specifying Color by the Munsell System

ASTM D3487 (2016) Standard Specification for Mineral Insulating Oil Used in Electrical Apparatus

ASTM D877/D877M (2013) Standard Test Method for Dielectric Breakdown Voltage of Insulating Liquids Using Disk Electrodes

ASTM D92 (2012a) Standard Test Method for Flash and Fire Points by Cleveland Open Cup Tester

ASTM D97 (2017a) Standard Test Method for Pour Point of Petroleum Products

FM GLOBAL (FM)

FM APP GUIDE (updated on-line) Approval Guide http://www.approvalguide.com/

INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS ( IEEE)

IEEE 386 (2016) Separable Insulated Connector Systems for Power Distribution Systems Rated 2.5 kV through 35 kV

IEEE C2 (2017; Errata 1 2017) National Electrical Safety Code

IEEE C37.47 (2011) Standard for High Voltage Distribution Class Current-Limiting Type Fuses and Fuse Disconnecting Switches

IEEE C57.12.00 (2015) General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers

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

- Enclosure Integrity

IEEE C57.12.29 (2014) Standard for Pad-Mounted Equipment

- Enclosure Integrity for Coastal Environments

IEEE C57.12.34 (2009) Standard for Requirements for Pad-Mounted, Compartmental-Type, Self-Cooled, Three-Phase Distribution Transformers, 5 MVA and Smaller; High Voltage, 34.5 kV Nominal System Voltage and Below; Low Voltage, 15 kV Nominal System Voltage and Below

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

IEEE C57.12.90 (2015; Corr 2017) Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers

IEEE C57.13 (2016) Requirements for Instrument Transformers

IEEE C57.98 (2011) Guide for Transformer Impulse Tests

IEEE C62.11 (2012) Standard for Metal-Oxide Surge Arresters for Alternating Current Power Circuits (>1kV)

IEEE Stds Dictionary (2009) IEEE Standards Dictionary: Glossary of Terms & Definitions

INTERNATIONAL ELECTRICAL TESTING ASSOCIATION (NETA)

NETA ATS (2017) Standard for Acceptance Testing Specifications for Electrical Power Equipment and Systems

NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)

ANSI C12.7 (2014) Requirements for Watthour Meter Sockets

NEMA 260 (1996; R 2004) Safety Labels for Pad-Mounted Switchgear and Transformers Sited in Public Areas

NEMA LI 1 (1998; R 2011) Industrial Laminating Thermosetting Products

NEMA Z535.4 (2011) American National Standard for Product Safety Signs and Labels

NEMA/ANSI C12.10 (2011) Physical Aspects of Watthour Meters

- Safety Standards

NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)

NFPA 70 (2017; ERTA 1-2 2017; TIA 17-1; TIA 17-2)

National Electrical Code

ORGANISATION FOR ECONOMIC CO-OPERATION AND DEVELOPMENT (OECD)

OECD Test 203 (1992) Fish Acute Toxicity Test

U.S. ENVIRONMENTAL PROTECTION AGENCY (EPA)

EPA 712-C-98-075 (1998) Fate, Transport and Transformation Test Guidelines - OPPTS 835.3100- "Aerobic Aquatic Biodegradation"

EPA 821-R-02-012 (2002) Methods for Measuring the Acute Toxicity of Effluents and Receiving Waters to Freshwater and Marine Organisms

U.S. NATIONAL ARCHIVES AND RECORDS ADMINISTRATION ( NARA)

10 CFR 431 Energy Efficiency Program for Certain Commercial and Industrial Equipment

UNDERWRITERS LABORATORIES (UL)

UL 467 (2013; Reprint Jun 2017) UL Standard for Safety Grounding and Bonding Equipment

1.2 RELATED REQUIREMENTS

Section 26 08 00 APPARATUS INSPECTION AND TESTING applies to this s ection, with the additions and modifications specified here in.

1.3 DEFINITIONS

Unless otherwise specified or indicated, electrical and electronics terms used in these specifications, and on the drawings, are as defined in IEEE Stds Dictionary .

1.4 SUBMITTALS

Government approval is required for submittals with a "G" designation;

submittals not having a "G" designation are for Con tractor Quality Control approval. Submittals with an "S" are for inclusion in the Sustainability eNotebook, in conformance with Section 01 33 29 SUSTAINABILITY REPORTING.

Submit the following in accordance with Section 01 33 00 SUBMITTAL

PROCEDURES:

SD-02 Shop Drawings

Pad-mounted Transformer Drawings ; G

SD-03 Product Data

Pad-mounted Transformers ; G

SD-06 Test Reports

Acceptance Checks and Tests ; G

SD-07 Certificates

Transformer Efficiencies ; G

SD-09 Manufacturer's Field Reports

Transformer Test Schedule ; G

Pad-mounted Transformer Design Tests ; G

Pad-mounted Transformer Routine and Other Tests ; G

SD-10 Operation and Maintenance Data

Transformer(s) , Data Package 5; G

1.4.1 Reduced Submittal Requirements

Transformers designed and manufactured by ABB in Je fferson City, MO; by Easton's Cooper Power Series Transformers in Waukes ha, WI; by ERMCO in Dyersburg, TN; or by Howard Industries in Laurel, M S need not submit the entire submittal package requirements of this contr act. Instead, the following items shall be submitted:

a. A certification, signed by the manufacturer, st ating that the manufacturer will meet the technical requirements o f this specification.

b. An outline drawing of the transformer with devices identified (paragraph PAD-MOUNTED TRANSFORMER DRAWINGS, item a ).

c. ANSI nameplate data of the transformer (paragra ph PAD-MOUNTED TRANSFORMER DRAWINGS, item b).

d. Manufacturer's published time-current curves in PDF format and in electronic format suitable for import or updating i nto the EasyPower computer program of the transformer high side fuses (paragraph PAD-MOUNTED TRANSFORMER DRAWINGS, item e).

e. Routine and other tests (in PART 2, see paragra ph SOURCE QUALITY CONTROL, subparagraph ROUTINE AND OTHER TESTS), con ducted by the manufacturer. These tests may be witnessed by the government. Provide transformer test schedule required by submittal ite m "SD-11 Closeout Submittals". Provide certified copies of the tests .

f. Provide acceptance test reports required by sub mittal item "SD-06 Test Reports".

g. Provide operation and maintenance manuals requi red by submittal item "SD-10 Operation and Maintenance Data".

1.5 QUALITY ASSURANCE

1.5.1 Pad-Mounted Transformer Drawings

Include the following as a minimum:

a. An outline drawing, including front, top, and s ide views.

b. IEEE nameplate data.

c. Elementary diagrams and wiring diagrams.

d. One-line diagram, including switch(es), current transformers, meters, and fuses.

e. Manufacturer's published time-current curves in PDF format and in electronic format suitable for import or updating i nto the EasyPower computer program of the transformer high side fuses .

1.5.2 Regulatory Requirements

In each of the publications referred to herein, con sider the advisory provisions to be mandatory, as though the word, "sh all" or "must" had been substituted for "should" wherever it appears. Inte rpret references in these publications to the "authority having jurisdi ction," or words of similar meaning, to mean the Contracting Officer. Provide equipment, materials, installation, and workmanship in accorda nce with NFPA 70 unless more stringent requirements are specified or indica ted.

1.5.3 Standard Products

Provide materials and equipment that are products o f manufacturers regularly engaged in the production of such product s which are of equal material, design and workmanship, and:

a. Have been in satisfactory commercial or industrial use for 2 years prior to bid opening including applications of equi pment and materials under similar circumstances and of similar size.

b. Have been on sale on the commercial market thro ugh advertisements, manufacturers' catalogs, or brochures during the 2- year period.

c. Where two or more items of the same class of eq uipment are required, provide products of a single manufacturer; however, the component parts of the item need not be the products of the same ma nufacturer unless stated in this section.

1.5.3.1 Alternative Qualifications

Products having less than a 2-year field service re cord will be acceptable if a certified record of satisfactory field operati on for not less than 6000 hours, exclusive of the manufacturers' factory or laboratory tests, is furnished.

1.5.3.2 Material and Equipment Manufacturing Date

Products manufactured more than 3 years prior to da te of delivery to site are not acceptable.

1.6 MAINTENANCE

1.6.1 Additions to Operation and Maintenance Data

Submit operation and maintenance data in accordance with Section 01 78 23 OPERATION AND MAINTENANCE DATA and as specified her ein. In addition to requirements of Data Package 5, include the followi ng on the actual transformer(s) provided:

a. An instruction manual with pertinent items and information highlighted

b. An outline drawing, front, top, and side views

c. Prices for spare parts and supply list

d. Routine and field acceptance test reports

e. Fuse curves for primary fuses

g. Actual nameplate diagram

h. Date of purchase

PART 2 PRODUCTS

2.1 PRODUCT COORDINATION

Products and materials not considered to be pad-mou nted transformers and related accessories are specified in Section 26 20 00 INTERIOR DISTRIBUTION SYSTEM, and Section 33 71 02 UNDERGROUND ELECTRICAL DISTRIBUTION.

2.2 THREE-PHASE PAD-MOUNTED TRANSFORMERS

IEEE C57.12.34 , IEEE C57.12.28 and as specified herein. Submit manufacturer's information for each component, devi ce, insulating fluid, and accessory provided with the transformer.

2.2.1 Compartments

Provide high- and low-voltage compartments separate d by steel isolating barriers extending the full height and depth of the compartments.

Compartment doors: hinged lift-off type with stop in open position and three-point latching.

2.2.1.1 High Voltage, Dead-Front

High-voltage compartment contains: the incoming li ne, insulated high-voltage load-break connectors, bushing well in serts, feed-thru inserts, six high-voltage bushing wells configured for loop feed application, load-break switch handle(s), access to oil-immersed bayonet fuses, tap changer handle, connector parking stands, protectiv e caps, and ground pad.

Minimum high-voltage compartment dimensions: IEEE C57.12.34 , Figures 16 and 17.

a. Insulated high-voltage load-break connectors: IEEE 386 , rated 15 kV, 95 kV BIL. Current rating: 200 amperes rms contin uous. Short time rating: 10,000 amperes rms symmetrical for a time duration of 0.17 seconds. Connector shall have a steel reinforced h ook-stick eye, grounding eye, test point, and arc-quenching contac t material.

c. Bushing well inserts and feed-thru inserts: IEEE 386 , 200 amperes, 15 kV Class. Provide a bushing well insert for each b ushing well unless indicated otherwise. Provide feed-thru inserts as indicated.

e. Load-break switch

Loop feed sectionalizer switches: Provide three, t wo-position, oil-immersed type switches to permit closed transit ion loop feed and sectionalizing. Each switch must be rated at 15 kV , 95 kV BIL, with a continuous current rating and load-break rating of 200 amperes, and a make-and-latch rating of 12,000 rms amperes symmetr ical. Locate the switch handles in the high-voltage compartment. Op eration of switches must be as follows:

ARRANGEMENT

NO.

DESCRIPTION OF

SWITCH ARRANGEMENT

SWITCH POSITION

LINE A SW. LINE B SW XFMR. SW

OPENCLOSE OPEN CLOSE OPEN CLOSE

1 Line A connected to Line B and both lines connected to transformer

X X X

2 Transformer connected to Line A only

X X X

ARRANGEMENT

NO.

DESCRIPTION OF

SWITCH ARRANGEMENT

SWITCH POSITION

LINE A SW. LINE B SW XFMR. SW

OPENCLOSE OPEN CLOSE OPEN CLOSE

3 Transformer connected to Line Bonly

X X X

4 Transformer open and loop closed

X X X

5 Transformer open and loop open

X X X

f. Provide bayonet oil-immersed, expulsion fuses in series with oil-immersed, partial-range, current-limiting fuses. The bayonet fuse links sense both high currents and high oil temperature in order to provide thermal protection to the transformer. Coordinate transformer protection with expulsion fuse clearing low-current faults and current-limiting fuse clearing high-current faults beyond the interrupting rating of the expulsion fuse. Include an oil retention valve inside the bayonet assembly housing, which closes when the fuse holder is removed, and an external drip shield to minimize oil spills.

Display a warning label adjacent to the bayonet fuse(s) cautioning against removing or inserting fuses unless the transformer has been de-energized and the tank pressure has been released.

Bayonet fuse assembly: 150 kV BIL.

Oil-immersed current-limiting fuses: IEEE C37.47 ; 50,000 rms amperes symmetrical interrupting rating at the system voltage specified.

g. Surge arresters: IEEE C62.11 , rated 9 kV, fully shielded, dead-front, metal-oxide-varistor, elbow type with resistance-graded gap. Provide six arresters for loop feed circuits.

h. Parking stands: Provide a parking stand near each bushing.

2.2.1.2 Low Voltage

Low-voltage compartment contains: low-voltage bushings with NEMA spade terminals, accessories, metering, stainless steel or laser-etched anodized aluminum diagrammatic transformer nameplate, and ground pad.

a. Include the following accessories: drain valve with sampler device, fill plug, pressure relief device, liquid level gage, pressure-vacuum gage, and dial type thermometer with maximum temperature indicator.2.2.2 Transformer

a. Less-flammable liquid-insulated, two winding, 60 hertz, 65 degrees C rise above a 30 degrees C average ambient, self-cooled type.

b. Transformer rated 500 kVA.

c. Transformer voltage ratings: 12470 V Delta 277 V GrdY 480 .

d. Tap changer: externally operated, manual type for changing tap setting when the transformer is de-energized. Prov ide four 2.5 percent full capacity taps, two above and two below rated p rimary voltage.

Indicate which tap setting is in use, clearly visib le when the compartment is opened.

e. Minimum tested percent impedance at 85 degrees C:

2.50 for units rated 75kVA and below

2.87 for units rated 112.5kVA to 300kVA

4.03 for 500kVA rated units

5.32 for units rated 750kVA and above

f. Comply with the following audible sound level l imits:

kVA DECIBELS

(MAX

75 51

112.5 55

150 55

225 55

300 55

500 56

750 57

1000 58

1500 60

2000 61

2500 62

g. Include:

(1) Lifting lugs and provisions for jacking under b ase, with base construction suitable for using rollers or skidding in any direction.

(2) An insulated low-voltage neutral bushing with N EMA spade terminal, and with removable ground strap.

(3) Provide transformer top with an access handhole .

(4) kVA rating conspicuously displayed using 3 inch high yellow letters on its enclosure.

2.2.2.1 Specified Transformer Efficiencies

Provide transformer efficiency calculations utilizi ng the actual no-load and load loss values obtained during the routine te sts performed on the actual transformer(s) prepared for this project. Reference no-load losses (NLL) at 20 degrees C. Reference load losses (LL) at 55 degrees C and at 50 percent of the nameplate load. The transformer is not acceptable if the calculated transformer efficiency is less than the efficiency indicated in the "KVA / Efficiency" table below. The table is b ased on requirements contained within 10 CFR 431 , Subpart K. Submit certification, including supporting calculations, from the manufacturer indi cating conformance.

kVA EFFICIENCY (percent)

15 98.65

30 98.83

45 98.92

75 99.03

112.5 99.11

150 99.16

225 99.23

300 99.27

500 99.35

750 99.40

1000 99.43

1500 99.48

2000 99.51

2500 99.53 above 2500 99.54

2.2.3 Insulating Liquid

a. Less-flammable transformer liquids: NFPA 70 and FM APP GUIDE for less-flammable liquids having a fire point not less than 300 degrees C tested per ASTM D92 and a dielectric strength not less than 33 kV tested per ASTM D877/D877M. Provide identification of transformer as "non-PCB" and "manufacturer's name and type of flui d" on the nameplate.

Provide a fluid that is a biodegradable, electrical insulating, and cooling liquid classified by UL and approved by FM as "less flammable" with the following properties:

(1) Pour point: ASTM D97, less than -15 degree C

(2) Aquatic biodegradation: EPA 712-C-98-075 , 100 percent

(3) Trout toxicity: OECD Test 203 , zero mortality of EPA 821-R-02-012 , pass

2.2.3.1 Liquid-Filled Transformer Nameplates

Provide nameplate information in accordance with IEEE C57.12.00 and as modified or supplemented by this section.

2.2.4 Corrosion Protection

Provide corrosion resistant bases and cabinets of t ransformers, fabricated of stainless steel conforming to ASTM A240/A240M , Type 304 or 304L. Base includes any part of pad-mounted transformer that i s within 3 inches of concrete pad.

Paint entire transformer assembly Federal Standard #20059 Dark Brown , with paint coating system complying with IEEE C57.12.28 regardless of base, cabinet, and tank material.

2.3 WARNING SIGNS AND LABELS

Provide warning signs for the enclosures of pad-mou nted transformers having a nominal rating exceeding 600 volts in accordance with NEMA Z535.4 and

NEMA 260.

a. When the enclosure integrity of such equipment is specified to be in accordance with IEEE C57.12.28 , such as for pad-mounted transformers, provide self-adhesive warning labels (decals, Pandu it No. PPSO710D72 or approved equal) on the outside of the high voltage compartment door(s)with nominal dimensions of 7 by 10 inches with the legend "WARNING HIGH VOLTAGE" printed in two lines of nomi nal 2 inch high letters. Include the work "WARNING" in white lette rs on an orange background and the words "HIGH VOLTAGE" in black le tters on a white background.

2.4 ARC FLASH WARNING LABEL

Provide arc flash warning label for the enclosure o f pad-mounted transformers. Locate this self-adhesive warning la bel on the outside of the high voltage compartment door warning of potent ial electrical arc flash hazards and appropriate PPE required. Provide labe l format as indicated..

2.5 GROUNDING AND BONDING

UL 467 . Provide grounding and bonding as specified in Se ction 33 71 02

UNDERGROUND ELECTRICAL DISTRIBUTION.

2.6 CAST-IN-PLACE CONCRETE

Provide concrete associated with electrical work as follows:

a. Composed of fine aggregate, coarse aggregate, p ortland cement, and water so proportioned and mixed as to produce a pla stic, workable mixture.

b. Fine aggregate: hard, dense, durable, clean, a nd uncoated sand.

c. Coarse aggregate: reasonably well graded from 3/16 inch to 1 inch .

d. Fine and coarse aggregates: free from injuriou s amounts of dirt, vegetable matter, soft fragments or other deleterio us substances.

e. Water: fresh, clean, and free from salts, alka li, organic matter, and other impurities.

f. Concrete associated with electrical work for ot her than encasement of underground ducts: 4000 psi minimum 28-day compressive strength unless specified otherwise.

g. Slump: Less than 4 inches . Retempering of concrete will not be permitted.

h. Exposed, unformed concrete surfaces: smooth, w ood float finish.

i. Concrete must be cured for a period of not less than 7 days, and concrete made with high early strength portland cem ent must be repaired by patching honeycombed or otherwise defective area s with cement mortar as directed by the Contracting Officer.

j. Air entrain concrete exposed to weather using a n air-entraining admixture conforming to ASTM C260/C260M.

k. Air content: between 4 and 6 percent.

2.7 SOURCE QUALITY CONTROL

2.7.1 Transformer Test Schedule

The Government reserves the right to witness tests. Provide transformer test schedule for tests to be performed at the manu facturer's test facility. Submit required test schedule and locati on, and notify the Contracting Officer 30 calendar days before schedul ed test date. Notify Contracting Officer 15 calendar days in advance of changes to scheduled date.

a. Test Instrument Calibration

(1) Provide a calibration program which assures tha t all applicable test instruments are maintained within rated accura cy.

(2) Accuracy: Traceable to the National Institute of Standards and Technology.

(3) Instrument calibration frequency schedule: les s than or equal to 12 months for both test floor instruments and lease d specialty equipment.

(4) Dated calibration labels: visible on all test equ ipment.

(5) Calibrating standard: higher accuracy than tha t of the instrument tested.

(6) Keep up-to-date records that indicate dates and test results of instruments calibrated or tested. For instruments calibrated by the manufacturer on a routine basis, in lieu of thi rd party calibration, include the following:

(a) Maintain up-to-date instrument calibration inst ructions and procedures for each test instrument.

(b) Identify the third party/laboratory calibrated instrument to verify that calibrating standard is met.

2.7.2 Design Tests

IEEE C57.12.00 , and IEEE C57.12.90 . Section 5.1.2 in IEEE C57.12.80 states that "design tests are made only on representative apparatus of basically the same design." Submit design test reports (comp lete with test data, explanations, formulas, and results), in the same s ubmittal package as the catalog data and drawings for the specified transfo rmer(s), with design tests performed prior to the award of this contract .

a. Tests: certified and signed by a registered pr ofessional engineer.

b. Temperature rise: "Basically the same design" for the temperature rise test means a pad-mounted transformer with the same coil construction (such as wire wound primary and sheet wound seconda ry), the same kVA, the same cooling type (ONAN), the same temperature rise rating, and the same insulating liquid as the transformer specified .

c. Lightning impulse: "Basically the same design" for the lightning impulse dielectric test means a pad-mounted transfo rmer with the same BIL, the same coil construction (such as wire wound primary and sheet wound secondary), and a tap changer, if specified. Design lightning impulse tests includes the primary windings only of that transformer.

(1) IEEE C57.12.90 , paragraph 10.3 entitled "Lightning Impulse Test Procedures," and IEEE C57.98 .

(2) State test voltage levels.

(3) Provide photographs of oscilloscope display wav eforms or plots of digitized waveforms with test report.

d. Lifting and moving devices: "Basically the sam e design" requirement for the lifting and moving devices test means a tes t report confirming that the lifting device being used is capable of ha ndling the weight of the specified transformer in accordance with IEEE C57.12.34 .

e. Pressure: "Basically the same design" for the pressure test means a pad-mounted transformer with a tank volume within 3 0 percent of the tank volume of the transformer specified.

f. Short circuit: "Basically the same design" for the short circuit test means a pad-mounted transformer with the same kVA a s the transformer specified.

2.7.3 Routine and Other Tests

IEEE C57.12.00 . Routine and other tests: performed in accordanc e with IEEE C57.12.90 by the manufacturer on the actual transformer(s) p repared for this project to ensure that the design performa nce is maintained in production. Submit test reports, by serial number and receive approval before delivery of equipment to the project site. Required tests and testing sequence as follows:

a. Phase relation

b. Ratio

c. No-load losses (NLL) and excitation current

d. Load losses (LL) and impedance voltage

e. Dielectric

(1) Impulse

(2) Applied voltage

(3) Induced voltage

f. Leak

PART 3 EXECUTION

3.1 INSTALLATION

Conform to IEEE C2 , NFPA 70 , and to the requirements specified herein.

Provide new equipment and materials unless indicate d or specified otherwise.

3.2 GROUNDING

NFPA 70 and IEEE C2 , except provide grounding systems with a resistanc e to solid earth ground not exceeding 925 ohms.

3.2.1 Grounding Electrodes

Provide driven ground rods as specified in Section 33 71 02 UNDERGROUND ELECTRICAL DISTRIBUTION. Connect ground conductors to the upper end of ground rods by exothermic weld or compression conne ctor. Provide compression connectors at equipment end of ground c onductors.

3.2.2 Pad-Mounted Transformer Grounding

Provide a ground ring around the transformer with 4 /0 AWG bare copper.

Provide two ground rods in the ground ring at oppos ite corners. Install the ground rods at least 10 feet apart from each other. Provide separate copper grounding conductors and connect them to the ground loop as indicated. When work in addition to that indicated or specified is required to obtain the specified ground resistance, the provision of the contract covering "Changes" applies.

3.2.3 Connections

Make joints in grounding conductors and loops by ex othermic weld or compression connector. Install exothermic welds an d compression connectors as specified in Section 33 71 02 UNDERGROUND ELECTRICAL DISTRIBUTION.

3.2.4 Grounding and Bonding Equipment

UL 467 , except as indicated or specified otherwise.

3.3 INSTALLATION OF EQUIPMENT AND ASSEMBLIES

Install and connect pad-mounted transformers furnis hed under this section as indicated on project drawings, the approved shop drawings, and as specified herein. Transformer connections shall be cabled and shall not be made utilizing manufactured bus duct.

3.4 FIELD APPLIED PAINTING

Where field painting of enclosures is required to c orrect damage to the manufacturer's factory applied coatings, provide ma nufacturer's recommended coatings and apply in accordance with manufacturer' s instructions.

3.5 FOUNDATION FOR EQUIPMENT AND ASSEMBLIES

Mount transformer on concrete slab as follows:

a. Unless otherwise indicated, provide the slab wi th dimensions at least 8 inches thick, reinforced with a 6 by 6 inches - W2.9 by W2.9 mesh placed uniformly 4 inches from the top of the slab.

b. Place slab on a 6 inch thick, well-compacted gravel base.

c. Install slab such that top of concrete slab is approximately 4 inches above the finished grade with gradual slope for dra inage.

d. Provide edges above grade with 1/2 inch chamfer.

e. Provide slab of adequate size to project at lea st 8 inches beyond the equipment.

Stub up conduits, with bushings, 2 inches into cable wells in the concrete pad. Coordinate dimensions of cable wells with tra nsformer cable training areas.

3.5.1 Cast-In-Place Concrete

Provide cast-in-place concrete work in accordance w ith the requirements of

ACI 318 .

3.5.2 Sealing

When the installation is complete, seal all entries into the equipment enclosure with an approved sealing method. Provide seals of sufficient strength and durability to protect all energized li ve parts of the equipment from rodents, insects, or other foreign m atter.

3.6 FIELD QUALITY CONTROL

3.6.1 Performance of Acceptance Checks and Tests

Perform in accordance with the manufacturer's recom mendations and include the following visual and mechanical inspections and electrical tests, performed in accordance with NETA ATS. Submit reports, including acceptance criteria and limits for each test in acc ordance with NETA ATS "Test Values".

3.6.1.1 Pad-Mounted Transformers

a. Visual and mechanical inspection

(1) Compare equipment nameplate data with specifica tions and approved shop drawings.

(2) Inspect physical and mechanical condition. Che ck for damaged or cracked insulators and leaks.

(3) Inspect anchorage, alignment, and grounding.

(4) Verify the presence of PCB content labeling.

(5) Verify the bushings and transformer interiors a re clean.

(6) Inspect all bolted electrical connections for h igh resistance using low-resistance ohmmeter, verifying tightness of accessible bolted electrical connections by calibrated torque- wrench method, or performing thermographic survey.

(7) Verify correct liquid level in tanks and bushin gs.

(8) Verify that positive pressure is maintained on gas-blanketed transformers.

(9) Perform specific inspections and mechanical tes ts as recommended by manufacturer.

(10) Verify de-energized tap changer position is le ft as specified.

(11) Verify the presence of transformer surge arres ters.

b. Electrical tests

(1) Perform resistance measurements through all bol ted connections with low-resistance ohmmeter.

(2) Verify proper secondary voltage phase-to-phase and phase-to-neutral after energization and prior to lo ading.

(4) Perform turns-ratio tests at all tap positions.

(5) Perform insulation power-factor or dissipation- factor tests on all windings in accordance with test equipment manufact urer’s published data.

(6) Perform power-factor or dissipation-factor test s on each bushing equipped with a power-factor/capacitance tap. In t he absence of a power-factor/capacitance tap, perform hot-collar te sts.

(7) Measure the resistance of each high-voltage win ding in each de-energized tap-changer position. Measure the res istance of each low-voltage winding in each de-energized tap-change r position, if applicable.

(8) Remove and test a sample of insulating liquid f or the following:

Dielectric breakdown voltage, Acid neutralization n umber, Specific gravity, Interfacial tension, Color, Visual Conditi on, Water in insulating liquids (Required on 25 kV or higher vol tages and on all silicone-filled units.), and Power factor or di ssipation factor.

(9) Perform dissolved-gas analysis (DGA) on a sampl e of insulating liquid.

3.6.1.2 Grounding System

a. Visual and mechanical inspection

(1) Inspect ground system for compliance with contr act plans and specifications.

b. Electrical tests

(1) Perform ground-impedance measurements utilizing the fall-of-potential method. On systems consisting of interconnected ground rods, perform tests after interconnections a re complete.

On systems consisting of a single ground rod perfor m tests before any wire is connected. Take measurements in normal ly dry weather, not less than 48 hours after rainfall. Use a porta ble ground resistance tester in accordance with manufacturer's instructions to test each ground or group of grounds. Use an in strument equipped with a meter reading directly in ohms or f ractions thereof to indicate the ground value of the ground rod or grounding systems under test.

(2) Submit the measured ground resistance of each g round rod and grounding system, indicating the location of the ro d and grounding system. Include the test method and test setup (i. e., pin location) used to determine ground resistance and s oil conditions at the time the measurements were made.

3.6.1.3 Surge Arresters, Medium- and High-Voltage

a. Visual and mechanical inspection

(1) Compare equipment nameplate data with specifica tions and approved shop drawings.

(2) Inspect physical and mechanical condition.

(3) Inspect anchorage, alignment, grounding, and cleara nces.

(4) Verify the arresters are clean.

(5) Inspect all bolted electrical connections for h igh resistance using low-resistance ohmmeter, verifying tightness of accessible bolted electrical connections by calibrated torque- wrench method, or performing thermographic survey.

(6) Verify that the ground lead on each device is i ndividually attached to a ground bus or ground electrode.

b. Electrical tests

(1) Perform resistance measurements through all bol ted connections with low-resistance ohmmeter, if applicable.

(2) Perform an insulation-resistance test on each a rrester, phase terminal-to-ground.

(3) Test grounding connection.

3.6.2 Follow-Up Verification

Upon completion of acceptance checks and tests, sho w by demonstration in service that circuits and devices are in good opera ting condition and properly performing the intended function. As an e xception to requirements stated elsewhere in the contract, notify the Contra cting Officer 5 working days in advance of the dates and times of checking and testing.

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