City and County of San Francisco
Office of Contract Administration
Purchasing
ITSF16000015/CD
Attachment B-6
SECTION 261213 – LIQUID-FILLED MEDIUM-VOLTAGE TRANSFORMERS
PART 1 - GENERAL
1.1
SUMMARY
A.
Related Documents:
1.
Drawings and general provisions of the Subcontract apply to this Section.
2.
Review these documents for coordination with additional requirements and
information that apply to work under this Section.
B.
Section Includes:
1.
Liquid filled subsurface submersible distribution transformers.
2.
Transformers shall include all standard and optional accessories as listed in this
specification.
C.
Related Sections:
1.
Division 01 Section "General Requirements."
2.
Division 01 Section "Special Procedures."
3.
Division 03 Section "Cast-in-Place Concrete."
4.
Division 26 Section "Common Work Results for Electrical".
5.
Division 26 Section "Secondary Unit Substations".
1.2
REFERENCES
A.
General:
1.
The following documents form part of the Specifications to the extent stated. Where
differences exist between codes and standards, the one affording the greatest
protection shall apply.
2.
Unless otherwise noted, the referenced standard edition is the current one at the
time of commencement of the Work.
3.
Refer to Division 01 Section "General Requirements" for the list of applicable
regulatory requirements.
4.
Refer to Division 26 Section "Common Results for Electrical" for codes and
standards, and other general requirements.
B.
ANSI – American National Standards Institute:
1.
ANSI/NFPA 70
National Electrical Code.
2.
ANSI/IEEE C57.12.00
General Requirements for Liquid-Immersed Distribution,
Power, and Regulating Transformers.
3.
ANSI C57.12.10 Requirements for Transformers 230000 Volts and Below.
4.
ANSI C57.12.13 Conformance Requirements for Liquid-Filled Transformers Used
in Unit Installations, Including Unit Substations.
5.
ANSI C57.12.26 Requirements for Pad-Mounted, Compartmental-Type, SelfCooled, Three-Phase Distribution Transformers for Use with Separable Insulated
High-Voltage Connectors.
261213-1
LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015
City and County of San Francisco
Office of Contract Administration
Purchasing
6.
7.
8.
9.
ITSF16000015/CD
Attachment B-6
ANSI C57.12.27 Conformance Requirements for Liquid-Filled Distribution
Transformers Used in Pad-Mounted Installations, Including Unit Substations.
ANSI C57.12.70 Terminal Markings and Connections for Distribution and Power
Transformers.
ANSI/IEEE C57.12.90
Test Code for Liquid-Immersed Distribution and Power
Transformers.
ANSI/IEEE 386 Separable Insulated Connector Systems for Power Distribution
Systems Above 600 V.
C.
ASTM International:
1.
ASTM D877 Test Method for Dielectric Breakdown Voltage of Insulating Liquids
Using Disk Electrodes.
D.
NEMA – National Electrical Manufacturers Association:
1.
NEMA TR 1 Transformers, Regulators and Reactors.
2.
NEMA TR 11 Small Power Transformers with 65 C Average Winding Rise and
Distribution Characteristics.
3.
NEMA 260
Safety Labels for Padmounted Switchgear and Transformers Sited in
Public Areas.
1.3
SUBMITTALS
A.
Submit under provisions of Division 26 Section "Common Results for Electrical - Review of
Materials" and Division 01 Section "General Requirements."
B.
Submit five (5) copies of shop drawings indicating outline dimensions, connection and
support points, weight, specified ratings and materials.
C.
Submit five (5) copies of certified transformer nameplate diagram.
D.
Submit five (5) copies of certified test data:
1.
Factory test data, including but not limited to the following:
a.
Resistance measurements of all windings
b.
Ratio tests
c.
Polarity and phase relation tests
d.
No-load loss at rated voltage
e.
Impedance
f.
Voltage and load loss at rated current
g.
Dielectric tests
2.
Previous test data on similar unit, in lieu of factory tests on actual units furnished,
including but not limited to the following:
a.
Impulse tests
b.
Temperature rise tests
c.
Sound tests
d.
Power factor tests
e.
Bushing tests
f.
Short circuit tests
E.
Submit five (5) copies of manufacturer's installation instructions.
261213-2
LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015
City and County of San Francisco
Office of Contract Administration
Purchasing
ITSF16000015/CD
Attachment B-6
F.
Submit approved Material Safety Data Sheet (MSDS) for cooling liquid.
G.
Operation and Maintenance Data:
1.
Submit five (5) operation and maintenance manuals.
2.
Include five (5) copies of procedures and for sampling and maintaining fluid, cleaning
unit, and replacing components.
3.
Furnish a list of, and prices for, any recommended special tools and spare parts to
permit proper maintenance and repair of the transformer.
1.4
QUALITY ASSURANCE
A.
Products shall be tested, approved and labeled/listed by Underwriters Laboratories, Inc., or
by a nationally recognized testing laboratory (NRTL) as listed in Division 26 Specification
"Common Work Results for Electrical."
B.
Electrical equipment and materials shall be new and within one year of manufacture,
complying with the latest codes and standards. No used, re-built, refurbished and/or remanufactured electrical equipment and materials shall be furnished on this project.
C.
Design and test transformers in accordance with the applicable ANSI/IEEE, NEMA and
ASTM standards listed in the References Article.
D.
Manufacturer's Qualifications: Company specializing in distribution transformers with 10
years experience.
1.5
A.
1.6
DELIVERY, STORAGE, AND HANDLING
Store and protect products under provisions of Division 01 Section "General
Requirements."
SEISMIC REQUIREMENTS
A.
The equipment, accessories, and supporting structures shall be designed in accordance
with the 2013 California Building Code Section 1705A.12.
B.
The primary steady state stresses shall be within the allowable working stress limits
accepted as good practice and set forth in the appropriate design standards. The primary
steady state stresses shall include those originating from gravity loads, operating loads,
and operating temperatures and should be combined with the seismic stresses.
PART 2 - PRODUCTS
2.1
MANUFACTURERS
ABB, Howard Industries, General Electric, or approved equal
261213-3
LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015
City and County of San Francisco
Office of Contract Administration
Purchasing
2.2
ITSF16000015/CD
Attachment B-6
LIQUID-FILLED SUBSURFACE SUBMERSIBLE TRANSFORMERS
A.
Liquid-filled Transformers: ANSI C57.12.26; three-phase, subsurface submersible, selfcooled transformer unit.
B.
Capacity: 500 KVA and 2,000 kVA, as shown on contract drawings.
C.
Primary Voltage: 12.47 kV, delta connected with two, 2 ½% primary taps above and below
rated voltage, with externally-operated, no-load tap changer. The tap changer shall have a
handle with provision for padlocking.
D.
Secondary Voltage: 277/480 volts, wye connected, solidly grounded neutral.
E.
Minimum Impedances: 5.75 percent for 2000 kVA. 4 percent for 500 kVA. Impedance
tolerances per ANSI / IEEE.
F.
Basic Impulse Level: 95 kV, HV; 30 kV, LV.
G.
Cooling and Temperature Rise; ANSI C57.12.22; Class OA. 65 deg C, self-cooled.
H.
Liquid: FR3 - biodegradable. Insulating liquid shall be shipped in the transformer tank.
I.
Accessories: The following accessory equipment shall be provided in accordance with
ANSI C57.12.26:
1.
Magnetic liquid level gage.
2.
Low liquid level sensor, Tedeco 3G7750, or approved equal.
3.
Top oil dial type thermometer with alarm contacts, Qualitrol 104 or approved equal.
4.
Pressure-vacuum gauge and regulator assembly, with pressure switch, Qualitrol 141,
or approved equal.
5.
Pressure relief device.
6.
Provisions for lifting and jacking.
7.
Base suitable for skidding and rolling in any direction.
8.
Hand hole in cover.
9.
Drain valve and sampling device and bottom filter press connection.
10. Top filling connection and filter press connection.
11. Grounding pads at base of tank.
J.
Primary Terminations: Bushing wells to ANSI/IEEE 386; provide three for radial feed.
Include bushings for insulated load break connectors.
K.
Secondary Terminations: Spade lugs, with extension for secondary cables, as required.
After termination and testing, connections shall be made waterproof for submersible
operation.
L.
Housing shall be submersible type for vault installation, with all accessories rated for
submersible service. Electrical switches shall be prewired to a submersion rated electrical
terminal box for ease of field wiring to the control and monitoring system.
M.
Sound level shall be in accordance with NEMA TR 1 standard.
261213-4
LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015
City and County of San Francisco
Office of Contract Administration
Purchasing
N.
2.3
ITSF16000015/CD
Attachment B-6
Finish Color: ANSI Z55.1, No. 61, light gray utilizing a phosphatizing and initial cleaning
treatment followed by a baked on epoxy primer and finish coats having a thickness of 3 to
5 mils.
CONSTRUCTION
A.
The transformer tank shall be stainless steel
B.
All exterior surfaces shall be coated using a system of coordinated and thoroughly tested
materials and application techniques that will assure long life under submersed or partially
submersed conditions in accordance with IEEE Special attention shall be given to welds,
seams, edges, and rough spots.
C.
No portion of the tank or protruding appurtenances shall trap or hold water.
D.
The hand-hole shall be bolted flanged type.
E.
Lifting shall be designed and located on the tank to avoid interference between lifting slings
and any attachments on the transformer, and to avoid scratching or marring the
transformer coating. The transformer shall contain suitable jacking and rolling facilities.
F.
All nuts, bolts, studs, and screws shall conform to the ANSI standards of pitch, thread
shapes, dimensions, and tolerances.
G.
The maximum average sound level as measured per IEEE shall be in accordance IEEE
C57.12.24.
H.
Each transformer shall be supplied with (3) primary bushing wells (1 per phase) and inserts
for use on a radial feed. Each bushing well shall be rated for the primary voltage and 200ampere continuous. They shall comply with all applicable requirements and Figure 3 of
IEEE 386. The transformer primary bushing wells shall be completely protected from paint
over-spray and other contamination that may occur during manufacture or shipping.
I.
Grounding pads or connecting points shall be provided near the high voltage bushings for
grounding each cable shield/neutral.
Secondary Connecting Equipment:
1.
The secondary neutral shall be grounded using a removable connection to the
casing ground pad in accordance with IEEE. The connections shall be sized for the
short circuit rating of the transformer. Short circuit durations are 2 seconds minimum
for transformers and below.
2.
Provisions shall be provided for removing the ground connection for testing purposes
on the secondary neutral for either internal or external connections.
J.
Bushings for transformer secondary windings
1.
The secondary voltage line bushing and neutral terminals shall be installed in
accordance with IEEE C57.12.24. The low voltage line and neutral bushing terminals
shall be copper spade lugs per IEEE C57.12.24 figure 4(c) unless approved
otherwise in writing from the Engineer Standards.
261213-5
LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015
City and County of San Francisco
Office of Contract Administration
Purchasing
2.4
ITSF16000015/CD
Attachment B-6
LABELING
A.
All labeling shall be in accordance with IEE E C57.12.24, IEEE C57.12.70, and IEEE
C57.12.00.
B.
Stenciled lettering on the tank shall mark bushings and designations. Decal will not be
allowed.
C.
The identification of voltage connections shall be shown on the instruction on the
nameplate.
D.
An instruction nameplate of stainless steel, or other approved corrosion-resistant material,
shall be provided. This nameplate shall be securely attached to the top of the transformer
by means of stainless steel or other non-corroding screws, rivets, or other approved
fasteners. The letters and numbers shall be stamped on the nameplate.
PART 3 - EXECUTION
3.1
EXAMINATION
A.
Verify that transformer pads are ready to receive work.
B.
Verify field measurements are as shown on Drawings.
C.
Verify that required utilities are available, in proper location and ready for use.
D.
Observe all restrictions imposed by safety tags and locks.
3.2
INSTALLATION
A.
SFPUC Contractor to install in accordance with manufacturer's instructions.
B.
SFPUC Contractor to install safety labels to NEMA 260. Manufacturer to provide safety
labels.
C.
Manufacturer to provide anchoring to meet all seismic supports and restraint requirements.
SFPUC Contractor to install all seismic supports.
3.3
TESTING
A.
The applicable Design Tests in accordance with IEEE C57.12.00 shall be successfully
performed for all designs.
B.
Each transformer shall have passed the following routine tests in accordance with IEEE
C57.12.00 and C57.12.90.
1.
Resistance Measurements of all windings on the rated voltage connection.
2.
Ratio tests.
261213-6
LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015
City and County of San Francisco
Office of Contract Administration
Purchasing
3.
4.
5.
6.
7.
8.
9.
10.
ITSF16000015/CD
Attachment B-6
Polarity and phase relation tests.
No-load losses and excitation current tests.
Load losses and impedance voltage.
Low frequency dielectric test.
Routine tests per section 10.4.
The completed transformer shall be pressure tested in accordance with Section 7.4.1
to insure that it is free from leaks and defects.
Oil dielectric tests from samples taken at the bottom of the units shall be performed
per ASTM D1816 (0.04 inch gap) after assembly is complete and prior to shipment.
Oil test results for the supplied oil in accordance with ASTM D3487 Table 1 or ASTM
6871 Table 1 shall be provided latest fluids shipment prior to transformer filling.
C.
A certified test report of all performed routine tests shall be supplied to the Engineer for
each unit to be delivered under this specification. Test reports should reach the Engineer
before the date of delivery of the units shipped, as this will be one of the bases of
acceptance of the shipment.
D.
The owner or its representatives may at any time perform audits, inspections, or observe
the supplier's operations. The supplier shall cooperate and provide access to
documentation, manufacturing, or testing. The owner's inspector shall be provided with full
access to the facilities used for manufacturing.
1.
These inspections do not relieve the supplier of their responsibilities for compliance
with all the requirements of these specifications.
2.
The owner will notify the supplier of any situation where the work is not in
accordance with the requirements of these specifications.
3.
All costs incurred by the supplier as a result of rejection of material shall be
considered incidental to the work. No separate payments shall be made.
3.4
SHIPPING AND PACKAGING
A.
All units to be shipped in open rack type flatbed trailers. Closed van type trailers are
unacceptable and will be rejected. Stacking of objects on top of each unit is not permitted.
B.
Units shall be mounted on a solid wooden pallet, or other approved pallet, for ease of
removal with forklift truck.
C.
Units shall be protected during shipment so as to prevent damage to all exterior surfaces
by the hold down devices. All parts of the transformer in contact with shipping hold-down
devices should be protected to prevent chafing or other damage. Units showing damage to
the paint finish are subject to rejection by the district and corrective action by the
manufacturer.
3.5
A.
DRAWINGS AND MANUALS
Drawings and technical data on the proposed transformer to be manufactured shall be
submitted to the Engineer - for review and approval prior to manufacturing or shipping.
1.
Preliminary dimension drawings shall be submitted with the bid form.
261213-7
LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015
City and County of San Francisco
Office of Contract Administration
Purchasing
B.
3.6
ITSF16000015/CD
Attachment B-6
These drawings shall include the following:
1.
Detailed drawing of the unit showing final dimensions, clearances, and weight
2.
Exterior mounted devices
3.
Parts list including catalog numbers
4.
Nameplate
5.
Installation, Maintenance, and Operation Instructions
6.
Recommended spare parts list
FIELD QUALITY CONTROL
A.
Test dielectric liquid to ASTM D877, using 25,000 volts minimum breakdown voltage, after
installation and before being energized.
B.
Test transformer to ANSI/IEEE C57.12.90.
C.
Provide the SFPUC with 5 certified copies of all field test reports.
3.7
A.
3.8
A.
ADJUSTING
Adjust primary taps so that secondary voltage is within 2 percent of rated voltage.
ACCEPTANCE
Final acceptance shall depend upon the satisfactory performance of the transformer under
test. Transformers shall not be energized until all test data and records are approved by
the SFPUC.
END OF SECTION 261213
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LIQUID-FILLED MEDIUM VOLTAGE TRANSFORMERS
APRIL 2015