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READ AND **REMOVE THIS PAGE** BEFORE PLACING

THE SPECIFICATION SECTION IN THE CONTRACT

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[DIVISION 16: ELECTRICAL]{.underline}

SECTION 16270 ‑ TRANSFORMERS

USE: Furnishing and installing power/distribution transformers.

**NOTES TO SPECIFIER:**

A. Options within paragraphs are identified by enclosure in brackets;
blank spaces enclosed by brackets \[\_\_\_\_\_\] provide for information
to be inserted, as appropriate, to individual projects.

B. **TO AVOID CONFLICTING REQUIREMENTS AND COSTLY MISTAKES,** the
specifier must edit (delete, substitute or add to the text). The
remaining paragraphs must be renumbered.

C. DELETE FOR FINAL COPY: Notes to the Specifier, located between lines
of asterisks; all \[brackets\], [underlining]{.underline}, **boldface**,
and *italics*, within the paragraphs; and this page. (Open Reveal Codes
\[alt F3\] to do this accurately.)

D. [To Edit "(Footer B)":]{.underline} (Corel 8). **ENTIRE FOOTER SHOULD
BE BOLDED.** Click in the footer and delete the "Project Name (ftr B)"
text and replace it with the **Name of the Project (upper and lower
case)**. Replace date with current MM/YY (WITHOUT BRACKETS).

E. The Guide Specifications are intended to be continuously reviewed and
revised. User's technical comments are appreciated. Also, other related
or similar specification that are written "from scratch" that could
benefit others, or other questions can be sent to NSTC A/E Group, ST
110, or call (303) 987-6868.

**DRAWING DATA REQUIRED:**

**REVISIONS OF THIS SECTION:**

CSI format, editorial changes: 12/01

Metric:

Technical Update: 2/97

**SECTION 16270**

**TRANSFORMERS**

**[PART 1: GENERAL]{.underline}**

**1.1 SUMMARY**

** A. Section Includes: \[Furnishing\] \[and\] \[installing\]
transformers indicated. **

**1.2 SUBMITTALS**

** A. General: Submittals shall be according to \[Section 01009 -
General Information and Requirements.\] \[Section 01300 - Submittals.\]
\[Section 01365 - Certificates of Conformance.\]**

** B. Manufacturer\'s Literature: Submit \[[ ]{.underline}\] copies of
the manufacturer\'s technical data for the transformers to be used on
this project. The literature shall include rated KVA, frequency, primary
and secondary voltages, percent taps, polarity, impedance, and
certification of transformer performance efficiency at 50% and 100%
load, percentage regulation at 100% and 80% power factor, no load and
full load losses in watts, percent impedance at 75 degrees C, hot‑spot
and average temperature rise above 40 degrees C ambient, sound level in
decibels, and standard published data.**

** C. Shop Drawings: Submit \[[ ]{.underline}\] copies of shop drawings
for the transformers to be used on this project. The shop drawings shall
indicate dimensions and weight loadings for transformer installations.
Show layout, wall brackets, platforms, vibration isolators, mountings,
and supports where applicable.**

**1.3 QUALITY ASSURANCE**

** A. Labeling Requirements: Dry‑type distribution transformers shall be
Underwriters Laboratories, Inc. (UL) listed and labeled. UL listing and
labeling will not be required if it can be shown that transformers meet
the requirements of another nationally recognized testing laboratory
(NRTL).**

**[PART 2: PRODUCTS]{.underline}**

**2.1 MATERIALS**

** A. General: Transformers shall be constructed of the manufacturer\'s
standard materials as listed in published product information; types and
sizes shall be as indicated or as required for the installation.**

** B. Overhead Pole‑type Distribution Transformers: Shall be according
to ANSI C57.12.00 & C57.12.20, factory‑assembled, single‑phase,
oil‑filled, protected, transformers. Transformer to be constructed for
continuous operation at rated KVA with temperature rise limited to a
maximum of 65 degrees C. Protected transformers are to include
valve‑type surge arresters, internal primary winding fuses, and
thermally actuated secondary breakers. For single phase loads on
grounded wye primary use overhead‑type rural protected units. For single
phase loads on ungrounded primary lines, or for three‑phase loads with
primary connected delta, use protected type two‑bushing transformers.
Transformers shall be provided with support lugs for pole, crossarm, or
platform mounting and with sidewall or cover mounted bushings as set by
primary voltage rating. Three low‑voltage porcelain bushings with
eye‑bolt terminals shall be suitable for application on either single
phase, wye, or delta connected secondary. Four 2‑1/2% below normal taps
and internal tap changer are required. Tank shall include grounding
connector, gasketed handhole cover, stenciled rating, automatic pressure
relief valve, and primer paint plus finish coat of light grey enamel.**

** C. Pad‑Mounted Single Phase Distribution Transformers: Shall be
according to ANSI C57.12.00 & C57.12.25, factory‑ assembled, oil‑filled,
compartmented, outdoor‑type, tamper‑resistant, transformers. Transformer
to be constructed for continuous operation at rated KVA with its surface
temperature rise limited to a maximum of 65 degrees C. High voltage
compartments to be supplied with two high‑voltage integral bushings for
universal load‑break elbow connectors. On transformers for use on
grounded‑wye systems, the two high‑voltage bushings shall be connected
for loop‑feed supply cables. An adjacent parking stand bracket is
required as well as an internal high voltage fuse and an externally
operated tap changer with four 2‑1/2% taps, two above and two below
normal. Secondary compartment shall include three bushings with spade
lugs, grounding stud or lug, automatic pressure relief valve, and oil
fill and drain plugs. An internal thermally operated secondary circuit
breaker is required. Steel enclosure shall include corrosion protection
plus weather‑resistant light blue‑green finish enamel, hinged cover or
doors to access wiring compartments, padlock provision, security cover
over bolt‑on cover to allow access to transformer, and lifting lugs.
Provide base as shown on the drawings.**

** D. Pad‑mounted Three Phase Distribution Transformers: Shall be
according to ANSI C57.12.00 & C57.12.26, factory‑ assembled, oil‑filled,
outdoor‑type, tamper‑resistant, compartmented transformers. Transformer
to be constructed to limit its surface temperature rise to 65 degrees C.
High voltage compartment to be arranged for three‑phase dead‑front loop
feed, with ground pad and parking stand brackets. Bushings shall be
universal load‑break type to accommodate load break elbow connectors.
Primary winding shall be delta connected and secondary winding shall be
wye connected with grounded neutral. Externally operable tap changer and
externally removable high‑voltage fuses are required. Secondary
compartment shall include four low voltage bushings with spade lugs, one
of which is to be an insulated neutral bushing with external removable
ground strap. Accessories required are a compartment barrier between
high‑ and low‑voltage compartments, automatic relief valve, and internal
low‑voltage circuit breaker. Steel enclosure shall include corrosion
protection plus weather‑resistant light blue‑green finish enamel, hinged
cover or doors to access wiring compartments, padlock provision, and
security cover over transformer compartment bolt‑on cover. Provide base
as shown on the drawings.**

** E. High‑Voltage Dry‑type Distribution Transformers: Shall be
according to ANSI C57.12.50 factory‑assembled, open coil, self‑cooled,
outdoor‑type, single‑ or three‑phase transformers. Construct transformer
for continuous operation at rated KVA with maximum of 65 degrees C
surface temperature rise. Connect three phase windings with primary in
delta and secondary in grounded wye. Provide four primary taps, two
above and two below rated voltage, for de‑energized tap changing
operation. Insulate transformer with Class 220 insulation. Provide
terminal enclosure, with hinged cover, to accommodate primary and
secondary coil wiring connections and electrical supply raceway terminal
conductor. Provide terminal board with clamp‑type connectors suitable
for copper or aluminum conductors. Terminal compartment temperature
shall not exceed 75 degrees C when transformer is operating at full load
in 40 degrees C ambient. Provide corrosion protected, fully enclosed,
weather‑resistant, steel enclosure. Paint with manufacturer\'s standard
light grey outdoor enamel over cleaned and phosphatized steel
enclosure.**

** F. General‑Purpose Dry‑type Distribution Transformers: Shall be
according to NEMA TR 1, factory‑assembled, general‑purpose, air‑cooled,
dry‑type transformers. Provide \[two 5% taps below normal\] \[six 2.5%
taps, 2 above and 4 below normal\] \[four 2.5% taps, 2 above and 2 below
normal\] for de‑energized tap‑changing operation. Insulate with Class
\[220 insulation and rate for 150 degrees C rise\] \[185 insulation and
rate for 115 degrees C rise\] \[150 insulation and rate for 115 degrees
C rise\] at continuous operation at rated KVA. Transformer surface
temperature rise to be limited to a maximum of 65 degrees C. Provide
terminal enclosure, with cover, to accommodate primary and secondary
coil winding connections and electrical supply raceway terminal
connector. Limit terminal compartment temperature to 75 degrees C when
transformer operates at rated KVA in 40 degrees C ambient. Cushion
transformer coil and core assembly from enclosure with vibration
isolation supports. Transformer sound‑level not to exceed ANSI/NEMA
standards for its KVA range. Transformers shall be suitable for wall
mounting. Steel enclosures shall be cleaned and phosphatized before
painting with light grey enamel.**

** G. Specialty Dry‑type Control Power Transformers: Shall be dry‑type,
step‑down, insulating transformer suitable for use in control circuits.
Transformers may be energy‑limiting or non‑energy‑limiting.
Non‑energy‑limiting transformers shall be provided with an overcurrent
protective device to limit the output current to a thermally safe
maximum value. Temperature rise measured on the outside of the enclosure
shall not exceed 60 degrees C at rated load for non‑energy‑limiting
units and 60 degrees C with secondary windings short‑circuited on
energy‑limiting units. An exception to this is an energy‑limiting unit
designed to burn out which shall not exceed an enclosure temperature of
125 degrees C. Where a protective device is required as part of
non‑energy‑limiting Class 2 transformers, it shall be reliably secured
inside the transformer enclosure.**

** H. K-rated Transformers: Shall have nonsinusoidal load current
handling capability to the degree defined by the designated K-factor. In
addition, the following criteria shall be met:**

**  1. Transformer design shall prevent overheating when carrying full
load with harmonic content corresponding to the designated K-factor.**

** 2. Nameplate shall state the designated K-factor of the
transformer.**

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

**ADD ADDITIONAL TRANSFORMERS AS NEEDED. (LIST AND DESCRIBE OTHER
SPECIAL TRANSFORMERS SUCH AS CURRENT TRANSFORMERS, INSTRUMENT
TRANSFORMERS, ISOLATION TRANSFORMERS, LOW‑TEMPERATURE‑RISE TRANS‑
FORMERS, AND VOLTAGE REGULATORS.)**

**\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\***

** I. \[[ ]{.underline}.\]**

**[PART 3: EXECUTION]{.underline}**

**3.1 INSTALLATION**

** A. General: Install transformers as indicated, complying with the
manufacturer\'s written instructions, applicable requirements of codes
and standards, and according to recognized industry practices.**

** B. Mountings: Provide vibration dampener mounts for indoor
transformers.**

** C. Connections: Connect transformer unit to electrical wiring system;
use flexible steel conduit or sealtight conduit at indoor transformer to
minimize noise and vibration. Unless otherwise indicated, three-phase
transformers shall have primaries connected in delta and secondaries
connected in grounded wye.**

PART 4: MEASUREMENT AND PAYMENT

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**WHEN A \"LUMP SUM\" CONTRACT IS USED, DELETE THE TITLE PART 4:
MEASUREMENT AND PAYMENT, AND BOTH ARTICLES FROM THIS SECTION.
MEASUREMENT AND PAYMENT WILL BE ADDRESSED IN PART 4 OF SECTION 01010
-SUMMARY OF WORK.**

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**4.1 METHOD OF MEASUREMENT**

** A. Units: The work described in this section will not be measured for
payment.**

**4.2 BASIS OF PAYMENT**

** A. Payment: No direct payment for the work described under this
section will be made. Consideration for this item shall be included in
the bid price for other items of the Contract.**

**END OF SECTION**