630253.1 1Ø Overhead Transformers
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Revision 19
Aug 19, 2020
1. Scope
This specification covers the requirements for furnishing and delivering single phase, 60-Hz, mineral-oil-immersed, self-cooled, overhead-type distribution transformer(s) rated 500 kVA or smaller, suitable for use on a 12.47 Grounded. Y/7.2kV electrical distribution system.
2. Reference Standards
All characteristics, definitions, terminology, voltage designations and tests, except as otherwise specified herein, shall be in accordance with the following industry standards for distribution, power and regulating transformers. When the following standards are superseded by an approved revision, the revision shall apply.
Industry Standards
ANSI/AIM BC2-1995Uniform Symbology Specification - Code 39
ANSI C57.12.00-2010IEEE Standard General Requirements for Liquid-Immersed Distribution, Power, and Regulating Transformers
ANSI C57.12.20-2011IEEE Standard for Overhead-Type Distribution Transformers, 500 kVA and Smaller: High Voltage, 34 500 V and Below; Low voltage 7970/13800Y V and Below
ANSI C57.12.31-2010IEEE Standard for Pole Mounted Equipment — Enclosure Integrity
ANSI C57.12.35-2013IEEE Standard for Bar Coding for Distribution Transformers
ANSI C57.12.37-2006IEEE Standard for the Electronic Reporting of Distribution Transformer Test Data
ANSI C57.12.70-2011IEEE Standard Terminal Markings and Connections for Distribution and Power Transformers
ANSI C57.12.80-2010IEEE Standard Terminology for Power and Distribution Transformers
ANSI C57.12.90-2010IEEE Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating Transformers and IEEE Guide for Short Circuit Testing of Distribution and Power Transformers
DOE Title 10 Part 431.191Distribution Transformers — Energy Conservation Standards and Their Effective Dates
NEMA TR 1 (R2000)Transformers, Regulators & Reactors
District Standards
Material Standard 387151.1 3-1/2" Labels for Marking District Owned Equipment
Material Standard 1000212.1 Non-PCB Label
3. Losses and Efficiency
3.1 No-Load Losses
No-load losses (core losses) shall be quoted in watts, referenced at 20°C in accordance with ANSI C57.12.00-2006.
3.2 Load Losses
Load losses (winding losses) shall be quoted in watts, referenced at 85°C in accordance with ANSI C57.12.00-2006.
3.3 Efficiency
Transformers shall meet the efficiency requirements of the U.S. Department of Energy as stated in DOE 10 CFR Part 431, Energy Conservation Program: Energy Conservation Standards for Distribution Transformers; Final Rule, as applicable.
4. Electrical Ratings, Material ID Numbers & DOE Minimum Efficiencies
| kVA Size | High Voltage | Low Voltage | Material ID | DOE Min. Efficiency |
|---|---|---|---|---|
| 1.5 | 7.2/12.47Y | 120/240 | 630253 | N/A |
| 10 | 7.2/12.47Y | 120/240 | --- | 98.70% |
| 10 | 7.2/12.47Y | 240/480 | --- | |
| 10 | 7.2/12.47Y | 120 | --- | |
| 15 | 7.2/12.47Y | 120/240 | 630427 | 98.82% |
| 15 | 7.2/12.47Y | 240/480 | 630419 | |
| 15 | 7.2/12.47Y | 120 | 630394 | |
| 25 | 7.2/12.47Y | 120/240 | 630534 | 98.95% |
| 25 | 7.2/12.47Y | 240/480 | 630518 | |
| 25 | 7.2/12.47Y | 120 | 630493 | |
| 25 | 7.2/12.47Y | 277 | 630526 | |
| 37.5 | 7.2/12.47Y | 120/240 | 630617 | 99.05% |
| 37.5 | 7.2/12.47Y | 240/480 | 630625 | |
| 37.5 | 7.2/12.47Y | 120 | 630592 | |
| 37.5 | 7.2/12.47Y | 277 | 630633 | |
| 50 | 7.2/12.47Y | 120/240 | 630708 | 99.11% |
| 50 | 7.2/12.47Y | 240/480 | 630716 | |
| 50 | 7.2/12.47Y | 120 | 630691 | |
| 50 | 7.2/12.47Y | 277 | 630724 | |
| 75 | 7.2/12.47Y | 120/240 | 630807 | 99.19% |
| 75 | 7.2/12.47Y | 240/480 | 630815 | |
| 75 | 7.2/12.47Y | 120 | 630790 | |
| 75 | 7.2/12.47Y | 277 | 630823 | |
| 100 | 7.2/12.47Y | 120/240 | 630906 | 99.25% |
| 100 | 7.2/12.47Y | 240/480 | 630914 | |
| 100 | 7.2/12.47Y | 120 | 630899 | |
| 100 | 7.2/12.47Y | 277 | 630922 | |
| 167 | 7.2/12.47Y | 120/240 | 631201 | 99.33% |
| 167 | 7.2/12.47Y | 240/480 | 631219 | |
| 167 | 7.2/12.47Y | 277 | 631227 | |
| 250 | 7.2/12.47Y | 120/240 | 631508 | 99.39% |
| 250 | 7.2/12.47Y | 240/480 | 631516 | |
| 250 | 7.2/12.47Y | 277 | 631524 | |
| 333 | 7.2/12.47Y | 120/240 | 631706 | 99.43% |
| 333 | 7.2/12.47Y | 240/480 | 631714 | |
| 333 | 7.2/12.47Y | 277 | 631722 | |
| 500 | 7.2/12.47Y | 120/240 | 632001 | 99.49% |
| 500 | 7.2/12.47Y | 240/480 | 632019 | |
| 500 | 7.2/12.47Y | 277 | 632027 |
5. Construction
5.1 Transformer Tank
The tank(s) shall be of welded steel construction free from leaks and seepage. The surface shall be properly cleaned and painted for protection against severe atmospheric conditions, oxygen, acid salts and alkalis.
All external fittings, cover bolts and clamping devices shall be of corrosion-resistant material.
When a handhole is provided, it shall be fitted with a moisture-resistant gasket and closing device.
A solderless connector which will accommodate AWG copper conductor size No. 8 solid to No. 2 stranded shall be located on the tank as indicated in ANSI C57.12.20-2011, Figure 11.
5.2 Finish
The transformer shall have a corrosion resistant finish that meets or exceeds the coating system requirements of ANSI C57.12.31-2010. The topcoat color of paint shall be semi-gloss ANSI Light Gray No. 70, Munsell Notation 5BG 7.0/0.4. Combined primer and topcoat thickness shall be no less than 3.0 mils. All finish components shall be lead free.
5.3 Transformer Size & Weight
Transformer dimensions and weights shall not exceed the values listed below:
| Size (kVA) | Height (in) | Width (in) | Depth (in) | Weight with Oil (lb) |
|---|---|---|---|---|
| 1.5 | 32 | 19 | 22 | 150 |
| 10 | 34 | 20 | 24 | 375 |
| 15 | 35 | 21 | 24 | 450 |
| 25 | 37 | 22 | 25 | 575 |
| 37.5 | 39 | 25 | 28 | 775 |
| 50 | 40 | 26 | 28 | 900 |
| 75 | 48 | 36 | 36 | 1,225 |
| 100 | 51 | 36 | 36 | 1,425 |
| 167 | 54 | 39 | 38 | 2,300 |
6. Components
6.1 High-Voltage Bushings
Transformers shall be equipped with two cover mounted high-voltage bushings positioned as indicated in ANSI C57.12.20-2011, Figure 11. Both primary bushings shall come equipped with moulded wildlife protectors with integral insulated handwheels for securing the primary and ground leads to the bushing terminals. The protectors shall be constructed from shatter, track, corrosion and UV resistant material with a high dielectric strength.
6.2 Low-Voltage Bushings
Low-voltage bushings on units 100 kVA and smaller shall be equipped with tank mounted, clamp type terminals. 120V and 277V units shall have two (2) low voltage bushings while 120/240V and 240/480V units shall have three (3) low voltage bushings per Table 7 of ANSI C57 12.20-2011. Units 167 kVA and larger shall have four (4) hole spades with NEMA hole spacing and be capable of accepting either copper or aluminum terminal lugs. Low voltage bushing insulation shall be manufactured from polymeric materials. Ceramic low voltage bushings are not acceptable.
A neutral grounding strap shall not be provided.
6.3 Primary Taps
Transformer(s) with 120/240 or 120 volt low-voltage ratings shall not have taps unless specified on the Special Provision Sheet.
Transformer(s) with 240/480 or 277 volt low-voltage ratings shall have two (2) 2.5% taps above and below rated voltage unless otherwise specified on the Special Provision Sheet. Tap changers when furnished shall be externally operable.
6.4 Transformer Oil
The transformer shall be shipped with the proper quantity of mineral insulating oil. Oil shall meet the requirements of ASTM D 3487 for Type II (inhibited) oil. At the time the oil is put into the tank it shall contain less than (1) ppm PCB certifiable by a laboratory test approved by the United States Environmental Protection Agency. The insulating oil, or any of its components, shall not be listed by IARC, NTP, OSHA or ACGIH as carcinogens. The successful bidder shall supply an MSDS sheet for each distinct formulation of insulating oil supplied to the District.
Alternative insulating fluids, including ester-based and silicone-based oils may be supplied with prior District review and approval.
6.5 Relief of Excessive Pressure
The transformer shall be equipped with a replaceable pressure relief valve as specified in Section 7.2.5.1 of ANSI C57 12.20-2011. A pressure relief cover assembly as the sole means of pressure relief is not acceptable.
7. Noise
Transformer sound levels shall not exceed the values listed below when measured in accordance with ANSI C57.12.90-2010:
| Equivalent Two-Winding kVA | Average Sound Level (Decibels) |
|---|---|
| 0-50 | 48 |
| 51-100 | 51 |
| 101-300 | 55 |
| 301-500 | 56 |
8. Identification
8.1 Nameplate
A corrosion-resistant nameplate shall be provided which conforms with Section 5.12 of ANSI C57.12.00-2010. Additionally, the nameplate shall show gallons of oil and total transformer weight with oil.
The following statement shall appear on the nameplate: “Contains less than 1 ppm PCB at the time of manufacture”.
Nameplates shall be bar coded in accordance with ANSI C57.12.35-2013.
8.2 kVA Decals
kVA decals, if specified in the Special Provisions Sheet, shall meet the following requirements.
The kVA size of the transformer shall be marked with 3” white reflective decals located immediately below the secondary bushings on the front surface. Marking decals shall conform to the latest revision of District Material Standard 387151.1.
A 10” high x 14” wide area centered on the bottom front of the transformer shall be left bare of any stenciling and/or decals.
8.3 Non- PCB Decal
A "NON-PCB" decal, if specified in the Special Provisions Sheet, shall meet the following requirements.
One “NON-PCB” decal shall be attached to each transformer. “NON-PCB” decals shall conform to the latest revision of District Material Standard 1000212.1 (see Figure 1).
The decals shall be positioned on the bottom half of the transformer tank, aligned with the center line of either the 2nd or 4th quadrants.
8.4 Labeling
Each transformer shall be labelled with the following information:
| Line | Data | Length | Example |
|---|---|---|---|
| 1 | District's Material Number* | 11 | "00006303130" *The number 0 must prefix the catalog number to fill 11 characters |
| 2 | District's Material Description | <= 50 | "Transformer, Underground 15 kVA Padmount (L) 240/120" |
| 3 | Date | 8 | "05/22/03" |
| 4 | "PO/REL" space PO Number (8 Characters) space Release Number (5 Characters) | 12 | "PO/REL 00001111 00001" |
| 5 | Transformer Serial Number | 12 | "000125875632" |
The decal shall be durable and weather resistant. The decal shall be placed on the transformer tank cover.
9. Test Reports
The bidder shall furnish certified copies of the short-circuit tests they have performed on each transformer design. Short-circuit tests shall be in accordance with ANSI/IEEE C57.12.00-2010 and C57.12.90-2010.
The District may reject any bid, when in its judgment, the bidder has not taken sufficient steps to meet the mechanical short-circuit requirements as detailed in the ANSI/IEEE standards.
10. Guarantee
The failure of any transformer due to defective design, material and/or workmanship within twelve months after being energized or eighteen months after delivery, whichever comes first, shall be repaired or replaced without cost to the District. Any defect in design, material and/or construction discovered within this period shall be corrected on all transformers furnished on this order at the manufacturer’s expense, either by repair or by replacement.
11. Inspection and Testing
After delivery, all of the delivered lot will be inspected for defects and conformance to this Specification and tested for proper internal connections. The manufacturer (or his representative) will be notified of all defects and mutual arrangements shall be made for correcting the defects at no expense to the District. All subsequent testing required due to the defects will be at the manufacturer’s expense.
12. Packaging
Transformers shall be shipped secured to individual nonreturnable wooden pallets suitable for handling with a forklift.
Transformers shall be shipped in an enclosed van. Transformers shipped on flatbed trucks, even if tarped or otherwise protected shall be refused and returned to vendor.
13. Bidder's Data
For each transformer line item, all bidders shall supply:
- One certified copy of all design tests as called for in ANSI C57.12.00-2010, Table 18.
- All data and information as requested on the attached bidder's data file.
A description of any proposed changes, additions or exceptions to the Specification shall be submitted along with reasons for the departure.
14. Data to be Furnished by the Successful Bidder
14.1 CAD Drawings
A CAD drawing outline dimensions of each transformer line item with accessories. Acceptable formats include Microstation, AutoCad or DXF.
14.2 Certified Transformer Test Data
Certified data for each transformer shall be submitted for each transformer at the time of shipment or other mutually agreed upon interval. Test data shall reported in electronic form, supplied as an ASCII file with variable length records, comma delimited. Fields shall be stripped of leading and trailing blanks. The data set shall include the standard and extended data sets per ANSI C57.12.37-2006 modified as given:
| Field | Field Name | Data Type | Sample Data | Valid Values |
|---|---|---|---|---|
| 1 | User Name | Char(20) | SNOHOMISH COUNTY PUD | SNOHOMISH COUNTY PUD |
| 2 | User Purchase Order Number | Char(8) | 00026350 | PO number including leading zeros. |
| 3 | User Stock Number | Char(10) | 0000630592 | Mat. ID number including leading zeros. |
| 4 | Producer Identification | Char(2) | HI | See ANSI C57.12.35-2007. |
| 5 | Producer Order Number | Char(14) | 4337 | |
| 6 | Producer Catalog Number | Char(15) | 1037-418997-000 | |
| 7 | Producer Serial Number | Char(13) | 1765201303 | |
| 8 | Product Type | Char(2) | PM | See ANSI C57.12.37-2006, 4.2.8. |
| 9 | Number of Phases | Int(1) | 1 | 1,2 or 3 |
| 10 | kVA Rating | Numeric(7,1) | 37.5 | Nominal ONAN kVA to 1 decimal point. |
| 11 | Primary Voltage | Char(47) | 12 470GrdY/7200 | See ANSI C57.12.00-2006. |
| 12 | Secondary Voltage | Char(28) | 240/120 | See ANSI C57.12.00-2006. |
| 13 | Polarity | Char(1) | S | A (Additive), S (Subtractive), Null (3Ø). |
| 14 | Quoted No-Load Loss | Int(5) | 45 | Quoted no-load losses in watts at nominal kVA, Pri. voltage & 20°C. |
| 15 | Quoted Load Loss | Int(6) | 201 | Quoted load losses in watts at nominal kVA, Pri. voltage & 85°C. |
| 16 | Quoted Impedance Voltage (IZ) | Numeric(4,2) | 2.57 | Quoted IZ in percent at nominal kVA, Pri. voltage & 85°C. |
| 17 | Quoted Excited Current (IEX) | Numeric(4,2) | 0.27 | Quoted IEX in percent at nominal kVA, Pri. voltage & 85°C. |
| 18 | Tested No-Load Loss | Int(5) | 44 | Tested no-load losses in watts at nominal kVA, Pri. voltage & 20°C. |
| 19 | Tested Load Loss | Int(6) | 189 | Tested load losses in watts at nominal kVA, Pri. voltage & 85°C. |
| 20 | Tested Impedance Voltage (IZ) | Numeric(4,2) | 2.6 | Tested IZ in percent at nominal kVA, Pri. voltage & 85°C. |
| 21 | Tested Resistance Voltage (IR) | Numeric(4,2) | 1.66 | Tested IR in percent at nominal kVA, Pri. voltage & 85°C. |
| 22 | Tested Exciting Current (IEX) | Numeric(4,2) | 0.30 | Tested IEX in percent at nominal kVA, Pri. voltage & 85°C. |
| 23 | Total Mass | Int(5) | 892 | Total mass, including accessories & oil. |
| 24 | Mass Unit of Measure | Char(2) | lb | lb (pounds), kg (kilograms). |
| 25 | Date of Manufacture | Char(7) | 2005/05 | Alphanumeric in yyyy/mm format. |
| 26 | Test Data Reporting Lot | Char(7) | 2005/05 | yyyy/mm or yyyy/qx where qx is Q1, Q2, Q3 or Q4. |
| 27 | User Release Number | Char(5) | 00107 | Release number including leading zeros. |
| 28 | Producer Plant Location | Char(10) | MSLAUREL | See ANSI C57.12.00-2006, 4.3.2. |
| 29 | Quoted Loss Guarantee Type | Char(2) | GA | See ANSI C57.12.00-2006, 4.3.3. |
| 30 | No-Load Loss Evaluation Factor | Numeric(5,2) | 5.2 | 00.00 to 99.99 |
| 31 | Load Loss Evaluation Factor | Numeric(5,2) | 1.23 | 00.00 to 99.99 |
| 32 | Frequency | Int(2) | 60 | Nominal operating frequency in hertz, 0 to 99. |
| 33 | Cooling Class | Char(9) | ONAN | ONAN, ONAN/ONAF, KNAN/KNAF or LNAN/LNAF. |
| 34 | Average Winding Temperature Rise | Char(5) | 65 | 55, 55/65, 65 or other as specified. |
| 35 | Type of Insulating Fluid | Char(8) | MIN_OIL | MIN_OIL, FR3, EnviroTemp, R TEMP or as specified. |
| 36 | No-Load Loss Reference Temperature | Int(2) | 20 | 0 to 99. |
| 37 | Load Loss Reference Temperature | Int(2) | 85 | 0 to 99. |
| 38 | Total Volume of Oil | Int(4) | 47 | 0 to 9999. |
| 39 | Volume Unit of Measure | Char(2) | GL | GL (gallons) or LT (liters). |
14.3 Equipment Data Sheet
Each shipment of transformers shall include a digital spreadsheet including all transformers in the shipment and their nameplate data. The spreadsheet shall be formatted to the District’s requirements and shall be emailed to the District’s Standards Department prior to delivery of each transformer shipment. The District will provide the required spreadsheet template to the manufacturer.