26 12 19.01 - LIQUID-FILLED MEDIUM-VOLTAGE PAD-MOUNTED TRANSFORMERS

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SECTION 26 12 19.01 - LIQUID-FILLED MEDIUM-VOLTAGE PAD-MOUNTED TRANSFORMERS

PART 1 - GENERAL

1.1 SCOPE

A. This specification covers the electrical and mechanical characteristics of Medium Voltage Step-Down Pad-Mounted Distribution Transformers.

1.2 APPLICABLE STANDARDS

A. All characteristics, definitions, and terminology, except as specifically covered in this specification, shall be in accordance with the latest revision of the following IEEE®, Department of Energy, and NEMA® standards:

1. IEEE Std C57.12.00™-2015 – IEEE Standard for Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers

2. IEEE Std C57.12.28™ - 2014 standard – Pad-Mounted Equipment - Enclosure

Integrity.

3. IEEE Std C57.12.29™ - 2014 standard - IEEE Standard for Pad-Mounted

Equipment - Enclosure Integrity for Coastal Environments – applicable when stainless steel construction is specified.

4. IEEE Std C57.12.34™-2015 standard – Standard Requirements for Pad-Mounted, Compartmental-Type, Self-Cooled, Three-Phase Distribution Transformers (2500 kVA and Smaller) - High Voltage: 34500GrdY/19920 Volts and Below; Low- Voltage: 480 Volt 2500 kVA and Smaller (issued in March 2005 - combines IEEE Std C57.12.22 and IEEE Std C57.12.26 standards).

5. IEEE Std C57.12.90™-2010 – IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers and IEEE Guide for Short- Circuit Testing of Distribution and Power Transformers

6. IEEE Std C57.12.91™-2011 standard – Guide for Loading Mineral-Oil-Immersed Transformers.

7. IEEE Std C57.154™ -2012 – IEEE Standard for the Design, Testing, and Application of Liquid-Immersed Distribution, Power, and Regulating Transformers Using High-Temperature Insulation Systems and Operating at Elevated Temperatures

8. NEMA® TR 1-1993 (R2000) – Transformers, Regulators and Reactors, Table 0-2 Audible Sound Levels

9. NEMA 260-1996 (2004) – Safety Labels for Pad-Mounted Switchgear and Transformers Sited in Public Areas.

10. 10 CFR Part 431 – Department of Energy–Energy Conservation Program: Energy Conservation Standards for Distribution Transformers; Final Rule

11. IEEE Std 386™-2016 – IEEE Standard for Separable Insulated Connector Systems for Power Distribution Systems Above 600 V.

1.3 RELATED SECTIONS

A. Division 26.

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1.4 SUBMITTALS

A. Submit under provisions of 01 33 00 - Submittals and 26 05 00 – Electrical-General.

B. Prior to ordering the transformer, the Contractor shall measure medium voltage between all phases and ground and submit the Engineer for review. The selected transformer shall be per the available voltage rating at the existing service transformer.

PART 2 - PRODUCTS

2.1 MANUFACTURERS

A. Eaton.

B. GE/ABB.

C. Approved Equal.

2.2 RATINGS

A. Prior to ordering the transformer, the Contractor shall field verify the voltage at the existing medium-voltage splice box as shown on the plans and submit to the Engineer for review. The primary voltage rating of the transformer listed within this specification and shown on the Plans is based on existing documentation and must be field verified.

B. The transformer shall be designed in accordance with this specification, and the base kVA rating shall be: 150 kVA.

C. The transformer shall have a high voltage of 13200 GrdY/7620, 3-phase and the basic lightning impulse insulation level (BIL) of 95 kV (see Part A above).

D. The secondary low voltage shall be 208/120V, 3-phase and the BIL of 30 kV.

E. The transformer shall be furnished with full capacity high-voltage taps. The tap changer shall be clearly labeled to reflect that the transformer must be de-energized before operating the tap changer as required in Section 4.3 of IEEE Std C57.12.34™-2015 standard. The tap changer shall be operable on the higher voltage only for transformers with dual voltage primaries. The unit shall have one of the following tap configurations:

1. Two – 2 ½% taps above and below rated voltage (split taps)

F. The average winding temperature rise above ambient temperature, when tested at the transformer rating, shall be 65°C average winding temperature rise rating. The above winding temperature rise shall not exceed 65°C when loaded at base kVA rating.

2.3 CONSTRUCTION

A. The core and coil shall be vacuum processed to ensure maximum penetration of insulating fluid into the coil insulation system. While under vacuum, the windings will be energized to heat the coils and drive out moisture, and the transformer will be filled with preheated filtered degassed insulating fluid. The core shall be manufactured from burr-free, grain-oriented silicon steel and shall be precisely stacked to eliminate gaps in the corner joints. The coil shall be insulated with B-stage, epoxy coated, diamond pattern, insulating paper, which shall be thermally cured under pressure to ensure proper bonding of conductor and paper. Coils shall be copper

B. The dielectric coolant shall be listed less-flammable fluid meeting the requirements of National Electrical Code Section 450-23 and the requirements of the National Electrical Safety Code (IEEE Std C2™-2002 standard), Section 15. The dielectric coolant shall be

Herbert, Rowland & Grubic, Inc. 26 12 19.01-3 005153.0436 non-toxic*, non-bioaccumulating and be readily and completely biodegradable per EPA OPPTS 835.3100. The base fluid shall be 100% derived from edible seed oils and food grade performance enhancing additives. The fluid shall not require genetically altered seeds for its base oil. The fluid shall result in zero mortality when tested on trout fry *.

The fluid shall be certified to comply with the US EPA Environmental Technology Verification (ETV) requirements and tested for compatibility with transformer components. The fluid shall be Factory Mutual Approved®, UL® Classified Dielectric Medium (UL-EOUV) and UL® Classified Transformer Fluid (UL-EOVK), Envirotemp™ FR3™ fluid. *(Per OECD G.L. 203)

C. In addition to the regular locking provision, all access doors or hood shall be secured by a recessed, captive, penta head bolt that meets the dimensions set forth in Rural Utilities Service (RUS) Drawing A3759 or IEEE C57.12.38

D. The transformer shall be of sealed tank construction of sufficient strength to withstand a pressure of 7 psig without permanent distortion, and 15 psig without rupturing or affecting cabinet security.

E. The tank shall include a pressure relief device as a means to relieve pressure in excess of pressure resulting from normal operation. The venting and sealing characteristics shall be as follows:

1. Cracking pressure: 10psig ± 2psig.

2. Resealing pressure: 6psig minimum.

3. Zero leakage from reseal pressure to -8psig.

4. Flow at 15 psig: 35 SCFM minimum.

F. The tank shall be complete with an anodized aluminum laser engraved nameplate.

Nameplate shall conform to IEEE Std C57.12.00™, nameplate A.

G. High Voltage Bushings and Terminals:

1. The high voltage bushings provided shall be externally clamped bushing wells.

These wells shall be removable to allow for field replacement of the bushings without opening the tank. Bushing Style.

2. The bushing configuration shall be per IEEE C57.12.38 Figure 1 (15 & 25 kV Class) and Figure 2 (35 kV Class) for ANSI® Type I units, or per Figure 3 (15 & 25 kV Class) and Figure 4 (35 kV Class) for ANSI® Type II units, or Eaton’s Cooper Power series unique Shrub Plus configuration which offers an ANSI® Type I high voltage bushing configuration and ANSI® Type II low voltage bushing configuration.

3. A cable accessory parking stand shall be provided and shall be located such that the separable insulated connectors that are designed for operation after the transformer is in place can be operated with hot-line tools.

H. Low Voltage Bushings and Terminals:

1. The configuration of the secondary bushings shall be per IEEE C57.12.38 Figure 1

(This specifies a horizontal or ANSI® Type I bushing arrangement) or Figure 3 (This specifies an angled or ANSI® Type II bushing pattern), or Eaton’s Cooper Power series unique Shrub Plus configuration which offers an ANSI® Type I high voltage bushing configuration and ANSI® Type II low voltage bushing configuration. These bushings shall be removable to allow for field replacement without opening the tank.

I. Overcurrent Protection:

1. Primary over-current protection shall be provided by a Bay-O-Net expulsion fuse with a flapper valve to minimize oil spillage. The Bay-O-Net assembly shall be used in series with an internally mounted isolation link.

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2. Secondary over-current and transformer overload protection shall be provided by a breaker installed on the secondary side of the transformer. This breaker shall have the capability to energize and de-energize the secondary service by one hotstick operation. This device shall be used in conjunction with an expulsion fuse on the primary side of the transformer.

J. Overvoltage Protection:

1. Primary overvoltage protection shall be provided by an internally mounted

M.O.V.E. distribution-class MOV elbow arrester.

K. Labeling:

1. A temporary bar code label shall be attached to the exterior of the transformer in accordance with IEEE Std C57.12.34™-2009 standard.

L. Finish Performance Requirements:

1. The tank coating shall meet all requirements in IEEE Std C57.12.28™-2014 standard including:

a. Crosshatch adhesion

b. Humidity

c. Impact

d. Insulating fluid resistance

e. Ultraviolet accelerated weathering

2. The enclosure integrity of the tank and cabinet shall meet the requirements for tamper resistance set forth in IEEE Std C57.12.28™-2014 standard including but not limited to the pry test, pull test, and wire probe test.

3. Additional transformer rating nameplate – In addition to the standard nameplate located on the transformer tank, a second nameplate shall be included. The nameplate shall be mounted external to the termination compartments with an industrial grade double-sided adhesive. Its location shall be identified on the data sheet.

M. The following standard accessories and options shall be provided:

1. 1.0” Upper Fill Plug with Filter Press Connection.

2. 1.0” Drain/Sampling Valve.

3. Bolted Cover.

4. Lifting Lugs (4).

5. Liquid Level Gauge.

6. Dial Type Thermometer.

7. Pressure/Vacuum Gauge.

PART 3 - EXECUTION

3.1 PRODUCTION TESTING

A. All units shall be tested for the following:

1. No-Load (85 °C or 20 °C) losses at rated current.

2. Total (85 °C) losses at rated current.

3. Percent Impedance (85 °C) at rated current.

4. Excitation current (100% voltage) test.

5. Ratio tests using all tap settings.

6. Polarity and phase relation tests.

7. Induced potential tests.

8. Full wave and reduced wave impulse test.

9. No load losses (10%) and total losses (6%).

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B. Transformers shall conform to efficiency levels for liquid immersed distribution transformers, as specified in the Department of Energy ruling “10 CFR Part 431 Energy Conservation Program: Energy Conservation Standards for Distribution Transformers;

Final Rule; April 18, 2013.” Manufacturer shall comply with the intent of all regulations set forth in noted ruling.

C. In addition, the manufacturer shall provide certification upon request for all design and other tests listed in IEEE Std C57.12.00™-2010 standard, including verification that the design has passed short circuit criteria per IEEE Std C57.12.00™-2010 standard and IEEE Std C57.12.90™-2010 standard.

D. In the event of proposal bid evaluated with guaranteed losses due to a loss evaluation (see section 10.0), manufacturer shall conform to guaranteed average losses as specified in IEEE Std C57.12.00™-2010 standard. The no-load losses of a transformer shall not exceed the specified no-load losses by more than 10%, and the total losses of a transformer shall not exceed the specified total losses by more than 6%.

3.2 SHIPPING

A. Transformers, 1000 kVA and below, shall be palletized. Transformers, 1500 kVA and larger, shall be loaded and unloaded with overhead cranes, so a pallet is not to be provided for these transformers.

3.3 DATA WITH PROPOSAL

A. The following data shall be submitted with the proposal:

1. Core losses.

2. Winding losses.

3. Percent Impedance.

4. Typical bid drawing.

5. Approval drawing – drawings shall show final dimensions and features. When requested, approval drawings shall be provided per quoted leadtime.

6. Record Drawing – drawings shall show final dimensions and features. When requested, record drawings shall be provided.

3.4 SERVICE

A. The manufacturer of the transformer shall have regional service centers located within two (2) hours flight time of all contiguous 48 states. Service personnel shall be factory trained in commissioning and routine service of quoted transformers.

END OF SECTION