Download Medium-Voltage Transformers

SECTION 26 1200
MEDIUM-VOLTAGE TRANSFORMERS
PART 1 - GENERAL
1.01
SUMMARY
A.
Section Includes: Single and three phase individually mounted transformers and
the transformer component of unit substation equipment operating at a voltage
greater than 600 volts, for power and lighting applications. and medium-voltage
transformers.
B.
Related Requirements:
C.
1.
Division 01 - General Requirements.
2.
Section 26 0500: Common Work Results for Electrical.
3.
Section 26 0513: Basic Electrical Materials and Methods.
4.
Section 26 0526: Grounding and Bonding.
5.
Section 26 0533: Raceways, Boxes, Fittings, and Supports.
6.
Section 26 0516: Medium Voltage Cables, Splices and Terminations.
7.
Section 26 1316: Medium-Voltage Metal-Enclosed Load Interrupter.
8.
Section 26 1100: Load Center - Unit Substations.
Codes and Applicable Standards: Transformers shall comply with all applicable
IEEE, ANSI, and NEMA Standards for medium voltage Dry-Type Transformers
including those with solid cast and/or resin-encapsulated windings.
1.
Department of Energy Policy Act of 2005 - Public Law 109-58.
2.
California Energy Commission Appliance Efficiency Regulations.
3.
California Building Code.
4.
ANSI/NFPA70, National Electrical Code, as adopted by the State of
California.
5.
IEEE C57.12.01, General Requirements for Dry-Type Distribution and
Power Transformers Including Those with Solid Cast and ResinEncapsulated Windings
PROJECT NAME
SCHOOL NAME
10/01/2011
MEDIUM-VOLTAGE TRANSFORMERS
26 1200-1
D.
1.02
6.
ANSI C57.12.51, Requirements for Ventilated Dry-Type Power
Transformers, 501 KVA and Larger, Three-Phase with High-Voltage 601
to 34 500 Volts, Low Voltage 208Y/120 to 4160 Volts
7.
ANSI C57.12.55, Dry-Type Transformers in Unit Installations, Including
Unit Substations - Conformance Standard
8.
ANSI/IEEE C57.98, Impulse Tests, Guide for Transformer (Appendix to
ANSI/IEEE C57.12.90)
9.
IEEE C57.12.91, Test Code for Dry-Type Distribution and Power
Transformers
10.
IEEE C57.94, Recommended Practice for Installation, Application,
Operation and Maintenance of Dry-Type General Purpose Distribution and
Power Transformers
11.
IEEE C57.96, Guide for Loading Dry-Type Distribution and Power
Transformers
12.
NEMA ST 20, Dry Type Transformers for General Applications
13.
OSHA 29 CFR 1910.145 Specification for Accident Prevention Signs and
Tags
ACRONYMS
ANSI
American National Standards Institute
OAR
Owner Authorized Representative
CEC
California Electrical Code
EOR
Engineer of Record
IBC
International Building Code
IEEE
Institute of Electrical and Electronics Engineers
NEC
National Electrical Code
NEMA
National Electrical Manufacturers Association
SUBMITTALS
A.
PROJECT NAME
SCHOOL NAME
Provide in accordance with Division 01.
10/01/2011
MEDIUM-VOLTAGE TRANSFORMERS
26 1200-2
B.
Shop Drawings: Include make, catalog number, dimensions, weight, KVA
rating, percent impedance, finish, type, insulation class, design temperature and
taps provided. Include regulation at 80 percent and 100 percent of full load, noload loss, full-load loss, percent efficiency, percent impedance, noise level and
continuous capacity rating. Provide point to point connection diagrams and
elevation details.
C.
Provide manufacturer’s data and inspection report that confirm compliance with
the requirements of this section.
D.
Provide a copy of the following test reports: Tests shall be performed on
transformers, in accordance with IEEE C57.12.91. EOR shall review the reports
for conformance with the specified criteria and applicable standards. Submit one
copy for each set of shop drawings:
1.
No-Load Losses.
2.
Load Losses: Measurements shall be taken at multiple levels and plotted to
show compliance with the specified criteria and applicable standards.
3.
Turn Ratio.
4.
Applied Potential (High-Pot).
5.
Temperature Rise.
6.
Induced Potential.
7.
Sound Level.
8.
Basic Impulse Insulation level (BIL).
9.
Impedance.
10.
Polarity and Phase Rotation.
11.
Exciting Current.
12.
Certified Test Report.
E.
1.03
Installation Instructions: Submit manufacturer's complete package of printed
installation instructions and connection diagrams.
WARRANTY
A.
PROJECT NAME
SCHOOL NAME
Transformers shall be warranted to be free from defects in materials, fabrication
and execution for three years from date of substantial completion.
10/01/2011
MEDIUM-VOLTAGE TRANSFORMERS
26 1200-3
PART 2 - PRODUCTS
2.01
EQUIPMENT
A.
Transformers manufactured by Square D, Siemens,
PowerSmiths, MGM, and Cutler Hammer or equal.
B.
Transformers shall be substation type with side-wall primary and secondary
terminations.
C.
Transformers shall be solid-cast, dry-type construction, mounted in a ventilated
enclosure. There shall be no exposed screws, bolts, or other fastening devices that
are externally removable.
D.
There shall be no openings through which foreign objects such as sticks, rods,
wires, or the like might contact live parts. Screen ventilated spaces from rodents
and foreign objects. Provide means for padlocking compartment door(s).
Padlocked locations shall be equipped with Corbin CAT 60 padlocks.
E.
The average temperature rise of the transformer windings shall not exceed 80
degrees C when the transformer is operated at full nameplate rating. The
transformer shall be capable of carrying 100 percent of the nameplate KVA rating
in a 40 degrees C maximum, 30 degrees C average ambient as defined by IEEE
C57.12.01.
F.
Terminations shall be side-wall mounted for close-coupling to high and low
voltage switchgear sections (Primary connection points shall have NEMA
standard termination lug holes).
G.
The transformer shall be rated as indicated on Drawings. The transformer shall be
furnished with two 2 ½ percent full capacity above normal and two 2 ½ percent
full capability below normal primary taps. Sound level shall not exceed the
maximum specified by NEMA TR-1 for the applicable KVA size of the
transformer.
H.
Primary and secondary windings shall be constructed of copper conductors.
Primary and secondary phase windings for each phase shall each be separately
cast as one rigid tubular coil, and arranged coaxially. Each cast coil shall be fully
reinforced with glass cloth, and cast under vacuum to provide complete, void-free
resin impregnation throughout the entire insulation system.
I.
The transformer core shall be constructed of high grade, grain-oriented silicone
steel laminations, with high magnetic permeability. Magnetic flux density is to be
kept well below the saturation point. The core shall be cruciform in shape, with
mitered joints to keep core losses, excitation current and noise level at a
minimum. The outside surfaces of the core shall be protected against corrosion by
painting with a suitable coating after assembly. Core dipping is not permitted.
PROJECT NAME
SCHOOL NAME
General
Electric,
10/01/2011
MEDIUM-VOLTAGE TRANSFORMERS
26 1200-4
J.
The enclosure shall be constructed of heavy-gage sheet steel, minimum 12-gage.
Ventilating openings shall be in accordance with NEMA and CEC standards for
ventilated enclosures. The cabinet shall be furnished with a minimum of four
hinged doors. The cabinet shall be furnished with door sills for easy panel
installation.
a.
Outdoor units shall be furnished with a NEMA 3R enclosure.
K.
The base shall be constructed to permit rolling or skidding in any direction, and
shall be furnished with jacking pads designed to be flush with the transformer
enclosure.
L.
Transformers shall be free of partial discharge up to at least 1.2 times the rated
line to ground voltage. High voltage coils shall be subjected to a partial discharge
test to verify its partial discharge.
M.
Each transformer to be installed under this section shall be sound tested at the
factory. Contractor shall provide two copies of transformers tests reports for EOR
review.
a.
Transformers up to 35 KVA shall be less than 40 decibels. Transformers
36 KVA or more shall be a minimum of five decibels below NEMA
standards per unit.
N.
Transformers shall be provided with vibration dampers consisting of Korfund,
Mason, or Caldynamics rubber pad and Elastorib sheeting. Size and number of
shock mounts shall be in accordance with manufacturer's recommendations.
O.
Transformers shall be UL listed.
P.
Verify all points of connection with the manufacturer’s requirements, instructions,
or recommendations prior to installation. Actual dimensions, weights, clearances
and installation requirements shall be verified and coordinated prior to
commencement of work.
Q.
Provide and install OSHA/CAL OSHA mandated bilingual (English and Spanish)
hazard warning signs on all accessible equipment sides containing access doors
and/or panels. The signs shall be a minimum of 14 inch by 10 inch in size and be
constructed on an aluminum backing. Design of signs shall be OSHA 29 CFR
1910.145 compliant with the words DANGER HIGH VOLTAGE KEEP OUT.
Signs shall be attached to its intended mounting surface with a minimum if ten
evenly distributed pop rivets for metal surfaces or tamper resistant screws on
metal or other surfaces provided that protruding portion of screws if any is
covered to eliminate the possibility of an injury.
PART 3 - EXECUTION
3.01
DELIVERY AND STORAGE
PROJECT NAME
SCHOOL NAME
10/01/2011
MEDIUM-VOLTAGE TRANSFORMERS
26 1200-5
A.
3.02
Deliver, storage, protect and handle products in accordance with the
manufacturer’s recommendations.
INSTALLATION
A.
Transformer core frame shall be installed level on shock absorbing pads with
enclosure.
B.
Mounting bolts shall be extended into pads only and shall not be in direct contact
with building structural members. Install transformer ventilation openings not
closer than six inches from any wall surface. Installation shall comply with CBC
seismic design requirements.
C.
Flexible jumpers shall be installed for grounding continuity from enclosure to
conduits or bus ducts where required.
D.
Transformers installed outdoors or below grade shall be installed on concrete pads
as described under Section 03 3000: Cast-In-Place Concrete and as detailed in
Drawings. Anchored bolts shall be tested to withstand 100 foot-pounds torque.
E.
Install according to manufacturer's installation instructions.
3.03
VOLTAGE CHECK
A.
Set taps on transformers as required providing satisfactory operating voltages with
present loads energized, including new loads and any existing loads.
B.
Provide instruments and accessories required to perform testing.
C.
Follow manufacturer's instructions for checking output voltage and voltage tap
changing.
3.04
PROTECTION
A.
3.05
Protect the Work of this section until Substantial Completion.
CLEANUP
A.
Remove rubbish, debris, and waste materials and legally dispose of off the Project
site.
B.
Repair scratched or marred surfaces affected during the execution of this work.
Repaired surfaces shall match original finish.
C.
Manufacturer to provide touch-up paint with delivery.
END OF SECTION
PROJECT NAME
SCHOOL NAME
10/01/2011
MEDIUM-VOLTAGE TRANSFORMERS
26 1200-6