SECTION 16450
DRY-TYPE TRANSFORMERS
PART 1 - GENERAL
1.01
REQUIREMENTS
A.
1.02
SCOPE
A.
1.03
The general provisions of the Contract, including General and Supplementary
Conditions and General Requirements, apply to the work specified in this
Section.
The work under this Section shall include furnishing and installing TP-1 dry-type
energy efficient transformers complete as shown on the Drawings and herein
specified. Provide all lugs, accessories and mounting hardware necessary for
proper installation and operation.
QUALITY ASSURANCE
A.
All equipment, materials and their installation shall conform to the requirements
of the National Electrical Code (NEC), local code requirements, and these
Specifications.
B.
Transformers shall meet the requirements of Federal Law 10 CFR Part 431
“Energy Efficiency Program for Certain Commercial and Industrial Equipment”
and bear the Energy Star® label.
C.
The transformer manufacturer shall be ISO 9001 or 9002 certified.
D.
All equipment and material shall be listed by Underwriter's Laboratories, Inc. (UL)
for their intended use and shall bear the UL label.
E.
Equipment shall be constructed and tested in accordance with National Electrical
Manufacturer's Association (NEMA) standards including TP-1, TP-2 and TP-3.
F.
Submittals are required in accordance with SECTION 16010 of these
Specifications. The following minimum information shall be submitted:
1.
Outline dimensions and weights.
2.
Technical certification sheet.
3.
Transformer ratings including:
a.
b.
c.
kVA
Primary and secondary voltage.
Taps.
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DRY-TYPE TRANSFORMERS
d.
e.
f.
4.
1.04
SECTION 16450
Design impedance.
Insulation class and temperature rise.
Sound level.
Product data sheets.
DELIVERY, STORAGE AND HANDLING
A.
Handle transformers in accordance with manufacturer’s recommendations.
Utilize factory provisions for all lifting, rigging, or hoisting.
B.
Store transformers prior to installation in a temperature and humidity controlled
space. If such a space is not available, apply temporary heat in accordance with
the manufacturer’s instructions within each ventilated type transformer case to
exclude moisture and condensation.
PART 2 - PRODUCTS
2.01
MATERIALS AND COMPONENTS
A.
Dry-type energy efficient transformers shall be indoor, dry, ventilated, quiet type
and shall be constructed and tested in accordance with the latest applicable
standards of ANSI, NEMA and UL.
B.
Ratings:
1.
KVA and voltage ratings shall be as shown on the drawings.
2.
Transformers shall be designed for continuous operation at rated kVA, for
24 hours a day, 365 days a year operation, with normal life expectancy as
defined in ANSI C57.96.
3.
Transformer sound levels shall not exceed the following ANSI and NEMA
levels for self-cooled ratings:
0
10
51
151
301
4.
to
to
to
to
to
9 kVA
50 kVA
150 kVA
300 kVA
500 kVA
40 dB
45 dB
50 dB
55 dB
60 dB
Transformers shall be low loss type with minimum efficiencies as listed in
NEMA TP-1 when operated at 35% of full load capacity. Efficiency shall
be tested in accordance with NEMA TP-2.
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DRY-TYPE TRANSFORMERS
C.
D.
SECTION 16450
Insulation Systems:
1.
Transformer insulation system shall be 220 degrees C insulation system
with 150 degree C rise, ventilated design.
2.
Required performance shall be obtained without exceeding the above
indicated temperature rise in a 40 degrees C maximum ambient, and a
24 hour average ambient of 30 degrees C.
3.
All insulation materials shall be flame-retardant and shall not support
combustion as defined in ASTM Standard Test Method D635.
Core and Coil Assemblies:
1.
Transformer core shall be constructed with high-grade, nonaging, silicon
steel with high magnetic permeability, and low hysteresis and eddy
current losses. Maximum magnetic flux densities shall be substantially
below the saturation point. The transformer core volume shall allow
efficient transformer operation at 10% above the nominal tap voltage.
The core laminations shall be tightly clamped and compressed. Coils
shall be wound of high quality electrical grade aluminum with continuous
wound construction.
2.
On three-phase units rated 15 kVA and above the core and coil assembly
shall be impregnated with non-hydroscopic, thermosetting varnish and
cured to reduce hot spots and provide a flame retardant seal and seal out
moisture. The assembly shall be installed on vibration-absorbing pads.
There shall not be any metal-to-metal contact between the core and coil
assembly and the enclosure except for a flexible safety ground strap.
E.
Three-phase transformers rated 15 through 500 kVA shall be provided with six 21/2% taps, two above and four below rated primary voltage.
F.
Enclosure:
1.
The enclosure shall be made of heavy-gauge steel. All transformers shall
be equipped with a wiring compartment suitable for conduit entry and
large enough to allow convenient wiring. The maximum temperature of
the enclosure shall not exceed 90 degrees C. The core of the
transformer shall be visibly grounded to the enclosure by means of a
flexible grounding conductor sized in accordance with applicable UL and
NEC standards.
2.
On three-phase transformers rated 15 kVA and above the enclosure
construction shall be ventilated, NEMA 2, drip-proof, with lifting holes. All
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DRY-TYPE TRANSFORMERS
SECTION 16450
ventilation openings shall be protected against falling dirt. Enclosures
shall be finished with ANSI gray color, weather-resistant enamel.
3.
G.
2.02
On ventilated outdoor units provide suitable weathershields over
ventilation opening, conforming to the requirements of NEMA 250, Type
3R. Suitable screens shall be provided to prevent insertion of foreign
debris and animals in the ventilation openings.
Dry-type transformers shall be as manufactured by EATON/CUTLER-HAMMER,
GENERAL ELECTRIC, SIEMENS, or SORGEL (SQUARE D).
NAMEPLATE
A.
Transformers shall have nameplates of 1/16 inch thick laminated plastic with
3/16 inch high white letters on a black background. Nameplates shall identify the
transformer and shall be mounted on the top front edge of the enclosure.
Nameplates shall be screw fastened using stainless steel screws. Nameplates
for transformers on emergency power shall have a red background.
PART 3 – EXECUTION
3.01
FACTORY TESTING
A.
3.02
The following standard factory tests shall be performed on the equipment
provided under this section. All tests shall be in accordance with latest version of
ANSI and NEMA standards.
1.
Ratio tests at the rated voltage connection and at all tap connections.
2.
Polarity and phase relation tests on the rated voltage connection.
3.
Applied voltage tests.
4.
Induced potential test.
5.
No-load and excitation current at rated voltage on the rated voltage
connection.
INSTALLATION
A.
Transformers, shown on the Drawings to be floor mounted shall have a four (4)
inch high by four (4) inch greater all sides concrete base. Connections shall be
made with flexible metal conduit.
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DRY-TYPE TRANSFORMERS
3.03
3.04
SECTION 16450
B.
Transformer manufacturer's nameplates, marked in accordance with NEMA
Specifications, shall be permanently attached to the transformer in a readily
accessible position.
C.
Transformer secondary neutral shall be grounded as per NEC requirements,
and/or hereinafter specified.
D.
This Contractor shall install the transformer to insure that the minimum
clearances required by the transformer manufacturer are provided. These
clearances shall be clearly labeled on the transformer by the manufacturer.
E.
Install units plumb, level and rigid without distortion.
ADJUSTMENTS AND CLEANING
A.
On completion of installation, inspect components. Remove paint splatters and
other spots, dirt and debris. Repair scratches and mars on finish to match
original finish. Clean components internally using methods and materials
recommended by the manufacturer.
B.
Adjust transformer taps to provide optimum voltage conditions at utilization
equipment throughout normal operating cycle of the facility. Measure and record
primary and secondary voltages and tap settings and submit with test results.
FIELD TESTING
A.
Include the following minimum inspections and tests according to manufacturer’s
written instructions. Comply with IEEE C57.12.91 for test methods and data
correction factors.
B.
Inspect accessible components for cleanliness, mechanical and electrical
integrity and damage or deterioration. Verify that temporary shipping bracing
has been removed. Include internal inspection through access panels and
covers.
C.
Inspect bolted electrical connections for tightness according to manufacturer’s
published torque values or, if not available, those specified in UL 486A and UL
468B.
END OF SECTION
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