City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
1.01
SCOPE OF WORK
This scope of work covers the design, manufacture, testing and delivery FOB destination of
two (2) power potential transformers for use with two (2) new static excitation systems at
Holm Power Plant as specified in these specifications and Attachments D and E. The new
excitation systems are ABB Unitrol 5000 systems, ABB model A5T-0/ASH1-A1250. The
systems are rated at 1100 amps DC continuous output with an AC input voltage of 320 volts.
1.02
QUALITY ASSURANCE
All materials used shall be new, of high grade and with properties best suited to the working
environment.
1.03
SUBMITTAL
All submittals shall conform to formats, conditions, and requirements as specified in
Attachment D – Submittals.
A.
Certificate of Compliance or complete list of all deviations from the drawings and
specifications.
B.
Submit transformer outline drawings with support point dimensions of enclosures and
accessories, unit weight, voltage, kVA and impedance ratings and characteristics, noload core loss, full load winding conductor loss, full load losses, efficiency at 25%,
50%, 75% and 100% rated loads. Provide data on sound level, tap configurations,
insulation system type and rated temperature rise. All information shall be in the
English language, clearly readable with IEEE, NEMA and ANSI symbols, device
numbers and other requirements.
C.
Submit manufacturer’s installation instructions and certification. Instruction shall
include procedures for items that are to be shipped disassembled but are to be
assembled and interconnected for operation when installed. Instructions shall contain
special rigging instructions as required for unloading, moving by skidding or rolling
and lifting the transformer and accessories.
D.
Submit O&M Manual and spare parts list. The O&M manual shall include provisions
for cleaning the unit and replacing components. Also included shall be instructions
for tap changing, enclosure assembly and disassembly, temperature indicator reading
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Attachment C-9/14/09
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City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
and setting procedures and other information designed to assist in proper operation
and periodic maintenance of the equipment being supplied.
All manuals, instructions and supporting drawings and parts lists supplied by the
manufacturer and supplemental instructions and data supplied by accessory
manufacturers shall be in English, clearly readable and arranged in such format as to
make the subject items easily identifiable. Each manual shall have an index and/or
table of contents identifying each item/subject and shall include the location (name of
manual, section, and/or page number) of information therein. All values shall be
given in English units and may be in both English and metric values. See Attachment
E, Operation and Maintenance Data.
1.04
REFERENCES
The publications listed below form a part of this specification to the extent referenced. The
publications are referred to in the text by basic designation.
A.
Institute of Electrical and Electronic Engineering
1.
IEEE C57.12.01 - (2005) Dry-Type Distribution and Power Transformers
Including Those with Solid Cast and/or Resin Encapsulated windings
2.
IEEE C57.12-91 - (2001) Test Code for Dry-Type Distribution and Power
Transformers
3.
IEEE C57.18.10-1998(2003) Semiconductor Power Rectifier Transformers
4.
IIEEE C57.110 – (2008) Establishing Transformer Capability When Supplying
Non-sinusoidal Load Currents.
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Attachment C-9/14/09
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City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
1.05
ENVIRONMENTAL RQUIREMENTS FOR POWER POTENTIAL TRANSFORMERS
The equipment and components furnished under this contract shall be capable of withstanding
any combination of the following external environmental conditions without mechanical or
electrical damage, or degradation of operating characteristics:
2.01
A.
Operating ambient temperature range: 0 to 40 degrees C.
B.
Storage (non-operating) ambient temperature range: Minus10 to plus 65 degrees C.
C.
Relative humidity range for above temperature ranges: 0 to 95%.
D.
Altitude above sea level 2227 ft.
E.
The equipment shall be designed for seismic stresses produced at the Holm Power
Plant as per the latest revision of the International Building Code. The equipment shall
be capable of normal function after being subjected to these stresses.
F.
Upon request, a certified copy of seismic calculations, signed by a licensed Civil or
Structural Engineer shall be submitted to show compliance of the equipment with the
requirements of subparagraph E. above.
POWER POTENTIAL TRANSFORMERS
A.
Rating
1.
Power Rating: 550kVA
2.
Cooling Class: Class AA
3.
Temperature Rise: 115 degrees Celsius
4.
Frequency: 60 Hz
5.
Phases: 3
6.
High Voltage Winding: 13.8kV with plus/minus 2 – 2-1/2% full capacity taps
7.
Low Voltage Winding: 0.32kV
8.
High Voltage Winding Connection: Delta
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Attachment C-9/14/09
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City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
9.
Low Voltage Winding Connection: Ungrounded Wye
10. High Voltage Winding BIL: 95kV
11. Low voltage Winding BIL: 10-kV
B.
General Construction
The power potential transformers shall be of the vacuum pressure encapsulated (VPE)
self cooled ventilated dry type conforming to the applicable requirements of IEEE
C57.12.01. The transformer shall be designed to handle non-linear loads and the
adverse effect of harmonics, conform to the recommended practice of IEEE C57.110,
and be designed specifically for supplying a thyristor-controlled rectifier load as per
the recommended practice of IEEE C57.18.10. The transformer shall be designed to
operate with the low voltage (LV) end up against the adjacent excitation cubicle
(supplied by Others).
C.
Winding
The transformer winding conductors shall be copper and insulated with class 220 deg.
C insulation. The transformers shall be equipped with an electrostatic shield to
prevent transmission of over voltages to the circuits of the transformer load (i.e.
excitation system). The winding insulation system between the high and low voltage
coils shall be more than sufficient for the voltage stress without the need for varnish.
The windings shall be supported by bottom supports and spacers. Hygroscopic
insulation materials shall not be allowed. The completed coil assembly shall be
vacuum pressure encapsulated (VPE) with a silicon resin meeting the requirements of
MIL-1-24092. The total VPE process shall apply a four (4) cycle shield of silicon
resin to the coils and a two (2) cycle protective shield to the bus, core and support
structure. The VPE process shall effectively encapsulate the entire core and coil
assembly which results in an assembly which is virtually impermeable to moisture,
dust, dirt, salt, air and other industrial contaminants.
D.
Core
All cores to be constructed of high grade, grain-oriented, non-aging silicon steel with
high magnetic permeability, and low hysteresis and eddy current losses. Magnetic
flux densities are to be kept well below the saturation point. Core laminations shall be
step-lap miter cut at the core corners to reduce hot spots, core loss, excitation current,
and sound level.
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Attachment C-9/14/09
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City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
E.
Enclosure and Mounting
The transformer enclosures shall be ventilated (indoor) and fabricated of heavy gauge,
sheet steel construction. Enclosures are to be provided with lifting provisions on the
base structure and shall have jacking pads designed to be flush with enclosure. The
base is to be constructed of steel members to permit skidding or rolling in any
direction. Rubber vibration isolation pads shall be installed by the manufacturer
between the core and coil and the enclosure. The transformer shall be furnished with a
high voltage terminal chamber containing a gang operated interrupting switch with
current limiting fuses. The high voltage load interrupter switch may be provided in a
separate compartment but if so furnished, the switch shall be designed such that can be
installed snug to the transformer enclosure and mounted on a common base with the
transformer. The common base will be supplied by Others. The switch shall be
manually operated and designed to interrupt magnetizing current of the power
potential transformer. Specific requirements for the interrupting switch and power
fuse cubicle include:
1.
Provide glass viewing window to verify switch position.
2.
Provide lockable handle in both OPEN and CLOSED positions.
3.
Provide HIGH VOLTAGE warning sign.
4.
Provide a firewall between the fused switch compartment and PPT cubicle.
5.
Mechanical interlocks to prevent entry into cubicle until switch is in open
position.
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Attachment C-9/14/09
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City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
6.
Current limiting type power fuses suitable rated for the power potential
transformer rating and with the capability of handling a short circuit
withstand of 25kA at the HV terminals of the transformer.
The enclosures shall be designed for floor mounting. Hinged doors shall be provided
for access to internal equipment. Adequate louvers for ventilation shall be provided.
High voltage cable entry to the interrupter and power fuse cubicle shall be from the
bottom. Cable entry for the low voltage connection shall be from the bottom.
Orientation of the transformer shall be with the primary on the left when facing the
front of the transformer. The power potential transformer (PPT) and the associated
excitation system it supplies will be mounted on an elevated base furnished by Others.
The elevated base will serve as a cable raceway system for the PPT low voltage
connections to the excitation system. The PPT will be mounted adjacent to the
excitation system in an arrangement similar to the arrangement shown on Hetch
Hetchy Water & Power Drawing H1-6502-00, "Excitation Control Board Equipment
Arrangement" which depicts the existing excitation system arrangement. The existing
PPT and its HV terminal compartment and fused disconnect switch have a "footprint"
of 92.25" wide by 42.25” deep. ABB Inc. Drawing E30-669-002, "Excitation System
General Arrangement" provides details on the new excitation system that the PPT
serves.
F.
Temperature Indication
The transformer shall be furnished with a temperature indicator mounted on the
transformer windings housing in a manner that facilitates reading of the indicator from
the maintenance aisle. The temperature indicator shall be equipped with a minimum
of two normally open contacts wired to provide alarm and trip functions. The contacts
shall be wired to terminal blocks isolated from the high voltage transformer chamber.
G.
Transformer Accessories
The transformers shall be furnished with the following accessories.
1.
Lifting lugs and jacking pads for lifting and moving
2.
Standard IEEE diagrammatic nameplate
3.
Grounding pads at two locations on opposite corners of the transformer. Pads
shall contain NEMA standard hole spacing for 2-hole, #4/0 lugs. A
grounding bus shall connect the two pads.
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Attachment C-9/14/09
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City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
H.
4.
120 VAC duplex receptacle
5.
120 VAC lighting fixtures, one (1) inside the disconnect switch compartment
and one (1) inside the transformer enclosure. Each lighting fixture shall be
controlled by a switch immediately inside each door or switched
automatically with door operations.
6.
Adequate 120VAC thermostatically controlled space heaters to prevent
moisture condensation inside the cubicles.
7.
Transformer HV & LV terminal lugs will be furnished by Others. The high
voltage load interrupter switch terminal lugs will be furnished by Others.
Painting
The interior and exterior steel surfaces of the power potential transformer and fuse
cabinet enclosure shall be thoroughly cleaned after fabrication by sandblasting,
pickling and rinsing, or by other means. They shall then receive a rust-inhibitive
phosphatizing or equivalent treatment prior to painting. Exterior surfaces shall then be
primed, filled where necessary, and given not less than two coats of quick air-drying
synthetic enamel with gloss finish color or heat fused epoxy powder coating. Interior
surfaces shall receive not less than one coat of corrosion-resisting paint in accordance
with the manufacturer’s standard practice. If the manufacturers’ standard paint process
differs from the just described process, the proposed paint process shall be submitted
to the City for approval. Paint color shall be ANSI 61.
I.
Spare Parts
The following spare parts shall be furnished and shipped with the transformer:
1.
J.
Three (3) current limiting fuses for the high voltage switch
Factory Tests
Perform factory tests on each transformer unit in accordance with IEEE C57.12.01 and
IEEE C57.12.91. In addition to the routine tests described in the test code, the
following specific tests should be performed.
1.
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Attachment C-9/14/09
Impulse test
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City And County of San Francisco
Office of Contract Administration
Purchasing Division
Bid Proposal No. ITSF10000217/CD
ATTACHMENT C
POWER POTENTIAL TRANSFORMERS FOR HOLM POWER PLANT STATIC
EXCITATION SYSTEMS
TECHNICAL SPECIFICATIONS FOR POWER POTENTIAL TRANSFORMER FOR
STATIC GENERATOR EXCITATION SYSTEMS
2.
Temperature rise test
3.
Audible sound test
4.
Overall power factor test of HV winding
5.
Overall power factor test of LV winding
6.
Excitation Current Test of HV winding
7.
100% Full Wave Impulse Test
A Certified test report should be submitted to Hetch Hetchy Water and Power for
review within 2-weeks following completion of such tests. Any transformer field
testing will be done by Others.
K.
Implementation/Testing
1. Contractor shall provide the cost per day for a qualified, factory trained, field
service representative to provide field support and assist in the implementation and
testing of the potential tranformers beyond that which is included in this base
proposal. Contractor’s filed service representative shall be responsible for
certifying in writing that the equipment has been installed, adjusted and tested in
accordance with the manufacturer’s recommendations.
2. It will be the responsibility of the contractor to pay all expenses related to this
required field service.
***END OF ATTACHMENT***
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