USACE / NAVFAC / AFCESA / NASA UFGS-26 13 00.00 20 (April 2006)
-------------------------------
Preparing Activity: NAVFAC Replacing without change
UFGS-16341N (February 2003)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 26 13 00.00 20
SF6 INSULATED PAD-MOUNTED SWITCHGEAR
04/06
NOTE: This guide specification covers the requirements for SF6 insulated, dead-front,
enclosed and non-enclosed, pad-mounted switchgear with load and fault interrupting
switched ways, with maximum ratings of 600 amperes and 38 kV, 60 Hz.
Edit this guide specification for project specific requirements by adding, deleting,
or revising text. For bracketed items, choose applicable items(s) or insert
appropriate information.
Remove information and requirements not required in respective project, whether
or not brackets are present.
Comments and suggestions on this guide specification are welcome and should
be directed to the technical proponent of the specification. A listing of technical
proponents, including their organization designation and telephone number, is
on the Internet.
Recommended changes to a UFGS should be submitted as a Criteria Change Request
(CCR).
NOTE: This guide specification can be used for subsurface (vault) applications
with appropriate modifications.
Use the following related guide specifications for power distribution equipment:
--Section 26 08 00 APPARATUS INSPECTION AND TESTING
--Section 26 12 19.10 THREE-PHASE PAD-MOUNTED TRANSFORMERS
--Section 26 12 19.20 SINGLE-PHASE PAD-MOUNTED TRANSFORMERS
--Section 33 71 01 OVERHEAD TRANSMISSION AND DISTRIBUTION
--Section 33 71 02.00 20 UNDERGROUND ELECTRICAL DISTRIBUTION
--Section 26 11 16 SECONDARY UNIT SUBSTATIONS
--Section 26 11 13.00 20 PRIMARY UNIT SUBSTATION
NOTE: The following information shall be indicated on the project drawings:
1. Site Plan showing location, space available, and desired arrangement of
switchgear.
2. Single-line diagram showing: nominal system voltage; number and configuration
of switched ways; type, number, and size of conductors for each circuit; and
method of power cable termination (200 ampere loadbreak connectors, or 600 ampere
deadbreak connectors). Individually identify each switched way as load or fault
interrupter and single-pole or three-pole tripping.
3. Grounding Detail with ground rods, ground loop and interconnecting cables
when interconnecting with other grounding systems or if multiple switches are
provided.
4. Special conditions, such as altitude, temperature and humidity, exposure
to fumes, vapors, dust, and gases.
PART 1 GENERAL
1.1 REFERENCES
NOTE: This paragraph is used to list the publications cited in the text of
the guide specification. The publications are referred to in the text by basic
designation only and listed in this paragraph by organization, designation,
date, and title.
Use the Reference Wizard's Check Reference feature when you add a RID outside
of the Section's Reference Article to automatically place the reference in the
Reference Article. Also use the Reference Wizard's Check Reference feature
to update the issue dates.
References not used in the text will automatically be deleted from this section
of the project specification when you choose to reconcile references in the
publish print process.
The publications listed below form a part of this specification to the extent referenced. The publications are
referred to within the text by the basic designation only.
[ASTM INTERNATIONAL (ASTM)ASTM A 167(1999; R 2004) Standard Specification for Stainless and Heat-Resisting Chromium-Nickel Steel Plate, Sheet, and StripASTM D 1535(2008) Specifying Color by the Munsell SystemASTM D 2472(2000; R 2006) Standard Specification for Sulphur Hexafluoride][INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)IEEE C2(2007; Errata 2007; INT 2008) National Electrical Safety CodeIEEE C57.12.28(2005) Standard for Pad-Mounted Equipment - Enclosure IntegrityIEEE C57.12.29(2005) Pad-Mounted Equipment - Enclosure Integrity for Coastal EnvironmentsIEEE C62.11(2005; Amendment A 2008) Standard for Metal-Oxide Surge Arresters for Alternating Current Power Circuits (>1kV)IEEE Std 386(2006) Standard for Separable Insulated Connector Systems for Power Distribution Systems Above 600V][INTERNATIONAL ELECTRICAL TESTING ASSOCIATION (NETA)NETA ATS(2003) Acceptance Testing Specifications][INTERNATIONAL ELECTROTECHNICAL COMMISSION (IEC)IEC 60265-1(1998; Corrigendum 2000) High Voltage Switches - Part 1: Switches for Rated Voltages Above 1 kV and Less Than 52 kVIEC 62271-111(2005) High Voltage Switchgear And Controlgear Part 111: Overhead, Pad-Mounted, Dry Vault, And Submersible Automatic Circuit Reclosers And Fault Interrupters For Alternating Current Systems Up To 38 Kv][NATIONAL ELECTRICAL MANUFACTURERS ASSOCIATION (NEMA)NEMA C37.72(1987) Manually-Operated, Dead-Front Padmounted Switchgear with Load Interrupting Switches and Separable Connectors for Alternating-Current Systems][NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)NFPA 70(2007; AMD 1 2008) National Electrical Code - 2008 EditionNFPA 70B(2006; Errata 2007) Electrical Equipment Maintenance][UNDERWRITERS LABORATORIES (UL)UL 467(2007) Standard for Grounding and Bonding Equipment]1.2 RELATED REQUIREMENTS
NOTE: Include Section 26 08 00 APPARATUS INSPECTION AND TESTING on all projects
involving medium voltage and specialized power distribution equipment.
Section 26 00 00.00 20 BASIC ELECTRICAL MATERIALS AND METHODS and Section 26 08 00 APPARATUS INSPECTION AND TESTING,
apply to this section, with the additions and modifications specified herein.
1.3 DEFINITIONS
1.3.1 Switched Way
A switched way is considered a three-phase circuit entrance to the bus through a switch. For single-phase switches,
it is a single-phase entrance to the bus through a switch.
1.4 SUBMITTALS
NOTE: Review submittal description (SD) definitions in Section 01 33 00 SUBMITTAL
PROCEDURES and edit the following list to reflect only the submittals required
for the project. Submittals should be kept to the minimum required for adequate
quality control.
A “G” following a submittal item indicates that the submittal requires Government
approval. Some submittals are already marked with a “G”. Only delete an existing
“G” if the submittal item is not complex and can be reviewed through the Contractor’s
Quality Control system. Only add a “G” if the submittal is sufficiently important
or complex in context of the project.
For submittals requiring Government approval on Army projects, a code of up
to three characters within the submittal tags may be used following the "G"
designation to indicate the approving authority. Codes for Army projects using
the Resident Management System (RMS) are: "AE" for Architect-Engineer; "DO"
for District Office (Engineering Division or other organization in the District
Office); "AO" for Area Office; "RO" for Resident Office; and "PO" for Project
Office. Codes following the "G" typically are not used for Navy, Air Force,
and NASA projects.
Choose the first bracketed item for Navy, Air Force and NASA projects, or choose
the second bracketed item for Army projects.
Government approval is required for submittals with a "G" designation; submittals not having a "G" designation
are [for Contractor Quality Control approval.][for information only. When used, a designation following the
"G" designation identifies the office that will review the submittal for the Government.] The following shall
be submitted in accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
SD-02 Shop Drawings
Switchgear Drawings; G
SD-03 Product Data
NOTE: Include the following paragraph when the switchgear will have fault
interrupting switched ways.
[Electronic Overcurrent Control Curves; G]
SF6 Insulated Pad-mounted Switchgear; G
Insulated High-Voltage Connectors; G
Surge Arresters; G
Each submittal shall include data on switches and associated accessories. Each submittal
shall include manufacturer's information for each component, device and accessory provided with
the equipment.
SD-06 Test Reports
Acceptance Checks and Tests; G
SD-07 Certificates
Paint Coating System; G
SD-09 Manufacturer's Field Reports
Switchgear design and production tests; G
SD-10 Operation and Maintenance Data
SF6 Insulated Pad-mounted Switchgear Operation and Maintenance, Data Package 5; G
Submit in accordance with Section 01 78 23 OPERATION AND MAINTENANCE DATA.
1.5 QUALITY ASSURANCE
1.5.1 Switchgear Drawings
Furnish drawings that include, but are not limited to, the following:
a. Overall dimensions, weights, plan view, and front view
b. Ratings
c. Single-line diagram.
1.5.2 Paint Coating System
NOTE: Select IEEE C57.12.29 when specifying stainless steel enclosures.
Submit [IEEE C57.12.28][IEEE C57.12.29] paint coating system performance requirement tests.
[1.5.3 Electronic Overcurrent Control Curves
Provide time-current characteristic curves (on full size logarithmic paper) and instruction manuals for the electronic
overcurrent control.
]1.6 MAINTENANCE
1.6.1 SF6 Insulated Pad-mounted Switchgear Operation and Maintenance Data
Submit Operation and Maintenance Manuals in accordance with Section 01 78 23 OPERATION AND MAINTENANCE DATA.
PART 2 PRODUCTS
2.1 SF6 INSULATED PAD-MOUNTED SWITCHGEAR
NOTE: Add reference to IEC 60265-1 for projects located in Europe only after
verifying that at least three manufacturers of this switchgear comply with this
standard.
NEMA C37.72[, IEC 60265-1]
2.1.1 Ratings and Test Requirements
The voltage rating of the switchgear shall be [15.5 kV][27 kV][38 kV][as indicated]. The corresponding ratings
associated with the required switchgear voltage rating shall be as follows:
NOTE: The following optional ratings are available for switchgear assemblies,
however, specifying these will require proprietary justification.
1. Optional short-time and short-circuit interrupting current ratings of 16,000
rms symmetrical amperes is available for both two and three position switchgear assemblies.
2. Optional short-time current rating of 25,000 rms symmetrical amperes is
available for switchgear assemblies configured with load interrupting switched
ways only.
3. For Norfolk Naval Shipyard projects, select optional 25,000 rms symmetrical
amperes short-time current rating for switchgear assemblies that are to be installed
on the 11.5 kV system.
Rated Maximum Voltage, kV [ 15.5 ][ 27 ][ 38]
Rated Withstand Impulse Voltage, kV BIL [ 95 ][ 125 ][ 150]
Continuous and Load Interrupting Current, A[ 600 ][ 600 ][ 600]
Short-Time Current, kA rms Sym [ 12 ][ 12 ][ 10]
[Short-Circuit interrupting Current,
kA rms Sym [ 12 ][ 12 ][ 12]]
Switched ways shall be rated for the required continuous and load interrupting current.[ Short-circuit interrupting
current rating applies to fault interrupting switched ways only.]
2.1.2 Switchgear Construction
NOTE: For LANTDIV projects select "three position switch: Open, Closed, Ground."
Switch contacts and cable entrance terminations shall be contained in an SF6 filled stainless steel tank. Switchgear
shall be shipped factory filled with SF6 gas conforming to ASTM D 2472. Switchgear shall be configured with[
load interrupting][ and][ fault interrupting] switched ways as indicated. Switchgear shall have front accessible
terminations suitable for cables entering from below[ with the manual operating provisions mounted on the rear].[
Switch contact positions for switched ways shall be visible through viewing windows in the SF6 tank located adjacent
to the manual operating provisions.] Provide gas pressure gage in viewable location from switch operating handle.
Each switched way shall have [three position switch; Open, Closed, Ground][provisions for grounding].
2.1.2.1 Pad-mounting Provisions
NOTE: Choose stainless steel enclosure where environmental conditions are not
suitable for mild steel or where a higher level of corrosion protection is desired.
Select IEEE C57.12.29 when enclosure is required to be stainless steel.
Provide [non-]enclosed switchgear suitable for installation on a concrete pad. Switchgear[ support frame][ enclosure
base][ enclosure] shall be fabricated of ASTM A 167 type 304 or 304L stainless steel.[ Enclosure base shall
include any part of the switchgear enclosure that is within 75 mm 3 inches of concrete pad.] Paint [switchgear
tank and support frame][enclosure including base] ASTM D 1535 Munsell 7GY3.29/1.5 green. Paint coating system
shall comply with [IEEE C57.12.28][IEEE C57.12.29] regardless of equipment material.
[2.1.3 Load Interrupting Switched Ways
Load interrupter switched ways shall provide[ single-pole][ three-pole group operated] switching[ as indicated].
][2.1.4 Fault Interrupting Switched Ways
NOTE: 1. Do not provide switchgear units configured with fault interrupting
switched ways where the system available fault current is greater than 16,000
rms symmetrical amperes.
2. Do not provide switchgear units configured with fault interrupting switched
ways at the Norfolk Naval Shipyard.
IEC 62271-111. Provide non-fused, non-reclosing, manual reset, vacuum interrupters consisting of vacuum bottles
and a spring assisted operating mechanism. Each fault interrupting switched way shall utilize internally mounted
current transformers and an electronic overcurrent control to provide[ single-pole][ three-pole ganged] tripping[
as indicated] for single-phase[ and three-phase] faults. The electronic overcurrent control shall have provisions
for a wide variety of field selectable time-current characteristic curves with ten field selectable trip levels
through a current range of[ 300][ 600] amperes.[ Fault interrupting switched ways shall have provisions for
remote tripping via an external dry contact device[ as indicated]. Provide[ 120 Vac][ 48 Vdc] remote trip control
power as indicated.]
][2.1.5 Key Interlock
NOTE: Add requirements for key interlock if needed. Provide details of interlock
system on the drawings.
Provide key interlock system as indicated on the drawings.
]2.1.6 Dead-Front High-Voltage Bushings
NOTE: Two types of cable entrances are available: 600 ampere deadbreak apparatus
bushings and 200 ampere loadbreak bushings. Choose the bushing, inserts and
connector appropriate for each of the specific applications.
If available fault is greater than 10,000 rms symmetrical amperes or if cable
size is greater than No. 4/0 AWG, do not use 200 A loadbreak elbow connectors.
IEEE Std 386. [15 kV, 95 kV BIL][25 kV, 125 kV BIL][35 kV, 150 kV BIL]. Provide[ 600 ampere one-piece deadbreak
apparatus bushings][ and][ 200 ampere bushing wells with bushing well inserts] for each switched way[ as indicated].
NOTE: Include standoff bushings only when the Activity requires the additional
items.
[a. Parking stands: Provide a parking stand near each dead-front bushing.[ Provide insulated
standoff bushings for parking of energized load-break connectors on each parking stands.]]
2.2 Insulated High-Voltage Connectors
IEEE Std 386. Provide corresponding connector for each switched way. Connectors shall have a steel reinforced
hook-stick eye, grounding eye, test point, and arc-quenching contact material.
[a. 200 Ampere loadbreak connector ratings: Voltage: [15 kV, 95 kV BIL][25 kV, 125 kV BIL][35
kV, 150 kV BIL]. Short time rating: 10,000 rms symmetrical amperes.]
NOTE: For LANTDIV projects, provide 200 ampere bushing interface on all 600
ampere connectors.
[b. 600 Ampere deadbreak connector ratings: Voltage: [15 kV, 95 kV BIL][25 kV, 125 kV BIL][35
kV, 150 kV BIL]. Short time rating: 40,000 rms symmetrical amperes.[ Connectors shall have
200 ampere bushing interface[ for surge arresters][ as indicated].]]
NOTE: Include the following paragraph only when the activity requires additional
grounding elbows and feed-thru inserts.
[c. Provide[ [one][____] set[s] of three grounding elbows][ and][ [one][____] set[s] of three
feed-thru inserts]. [Grounding elbows][ and ][feed-thru inserts] shall be delivered to the
Contracting Officer.]
[2.3 Surge Arresters
IEEE C62.11, rated[[ 3][ 6][ 9][ 10][ 12][ 15][_____] kV][ as indicated], fully shielded, dead-front, metal-oxide-varistor,
elbow type with resistance-graded gap, suitable for plugging into inserts. Provide arresters on switched ways
as indicated.
][2.4 SF6 Refill Cylinders
NOTE: Include the following paragraph only when the activity requires additional
SF6 refill cylinders.
Provide [two][____] SF6 refill cylinders, minimum size of 6 pounds of SF6; include regulator, valves, and hose
for connection to the fill valve of the switch.
]2.5 SOURCE QUALITY CONTROL
2.5.1 Switchgear Design and Production Tests
NOTE: Include IEC 62271-111 when the switchgear will have fault interrupting
switched ways.
NOTE: Add reference to IEC 60265-1 for projects located in Europe only after
verifying that at least three manufacturers of this switchgear comply with this
standard.
Furnish reports which include results of design and production tests performed according to NEMA C37.72[, IEC 60265-1
][ and IEC 62271-111]. Production tests shall be performed by the manufacturer on each switchgear assembly to
ensure that design performance is maintained in production.
PART 3 EXECUTION
3.1 INSTALLATION
Electrical installations shall conform to IEEE C2, NFPA 70, and to the requirements specified herein.
3.2 GROUNDING
NOTE: Where rock or other soil conditions prevent obtaining a specified ground
value, other methods of grounding should be specified. Where it is impractical
to obtain indicated ground resistance values, the designer should make every
effort, within reason, to obtain ground resistance values as near as possible
to the indicated values.
NFPA 70 and IEEE C2, except that grounds and grounding systems shall have a resistance to solid earth ground
not exceeding 5 ohms. When work, in addition to that indicated or specified, is directed to obtain the specified
ground resistance, the provision of the contract covering "Changes" shall apply.
3.2.1 Grounding Electrodes
Provide driven ground rods as specified in Section [33 71 02.00 20 UNDERGROUND ELECTRICAL DISTRIBUTION][_____][
at each corner of switchgear pad][ as indicated].
3.2.2 Switchgear Grounding
Connect #4/0 bare copper conductor ground loop, not less than 610 mm 24 inches below grade, to the upper end
of the ground rods by exothermic welds or compression connectors. Provide #4/0 bare copper conductors connecting
the switchgear grounding provisions to two different ground rods.
3.2.3 Connections
Make joints in grounding conductors and ground loop by exothermic weld or compression connector. Exothermic
welds and compression connectors shall be installed as specified in [Section 33 71 02.00 20 UNDERGROUND ELECTRICAL
DISTRIBUTION][_____].
3.2.4 Grounding and Bonding Equipment
UL 467, except as indicated or specified otherwise.
3.3 FOUNDATION FOR EQUIPMENT AND ASSEMBLIES
Mount switch on concrete slab. Slab shall be at least 300 mm 12 inches thick, reinforced with a 152 x 152 -
MW19 x MW19 6 x 6 - W2.9 x W2.9 mesh, placed uniformly 100 mm 4 inches from the top of the slab. Slab shall
be placed on a 150 mm 6 inch thick, well-compacted gravel base. Top of concrete slab shall be approximately
100 mm 4 inches above finished grade. Edges above grade shall have 15 mm 1/2 inch chamfer. Slab shall be of
adequate size to project at least 200 mm 8 inches beyond equipment.
Stub up conduits, with bushings, 50 mm 2 inches into cable wells in the concrete pad. Coordinate dimensions
of cable wells with switch cable training areas. Concrete work shall be as specified in Section 03 30 00 CAST-IN-PLACE
CONCRETE.
3.4 FIELD QUALITY CONTROL
3.4.1 Performance of Acceptance Checks and Tests
Perform in accordance with the manufacturer's recommendations, NFPA 70B, NETA ATS and referenced ANSI standards.
Include the following visual and mechanical inspections and electrical tests, performed in accordance with NETA ATS
.
3.4.1.1 Switchgear
a. Visual and Mechanical Inspection
(1) Compare equipment nameplate information with specifications and approved shop drawings.
(2) Inspect physical and mechanical condition.
(3) Check for proper anchorage, alignment, required area clearances, and grounding.
(4) Perform mechanical operator tests in accordance with manufacturer's instructions.
(5) Verify that insulating SF6 gas pressure is correct.
(6) Inspect all indicating devices for proper operation.
NOTE: Include the following option when key interlocking is specified.
[(7) Test interlock systems for proper operation and sequencing.]
b. Electrical Tests
(1) Perform contact-resistance tests.
[(2) Trip fault interrupters by operation of overcurrent control[ and remote trip].]
(3) Perform insulation-resistance tests.
(4) Perform an over-potential test on each switched way pole with the switched way in the open
position in accordance with the manufacturer's instructions.
[(5) Set fault interrupter overcurrent control in accordance with government provided settings.
Request settings from government, in writing, a minimum of 30 days prior to scheduling electrical
tests.]
3.4.1.2 Grounding System
a. Visual and Mechanical Inspection
Inspect ground system for compliance with contract plans and specifications.
b. Electrical Tests
Perform ground-impedance measurements utilizing the fall-of-potential method. On systems consisting
of interconnected ground rods, perform tests after interconnections are complete. On systems
consisting of a single ground rod perform tests before any wire is connected. Take measurements
in normally dry weather, not less than 48 hours after rainfall. Use a portable ground testing
megger in accordance with manufacturer's instructions to test each ground or group of grounds.
The instrument shall be equipped with a meter reading directly in ohms or fractions thereof
to indicate the ground value of the ground rod or grounding systems under test.
Submit the measured ground resistance of each ground rod and grounding system, indicating the
location of the rod and grounding system. Include the test method and test setup (i.e., pin
location) used to determine ground resistance and soil conditions at the time the measurements
were made.
3.4.2 Follow-Up Verification
Upon completion of acceptance checks and tests, the Contractor shall show by demonstration in service that devices
are in good operating condition and properly performing the intended function. Test shall require each item to
perform its function not less than three times. As an exception to requirements stated elsewhere in the contract,
notify the Contracting Officer 5 working days in advance of the dates and times for checks and tests.