USACE / NAVFAC / AFCESA / NASA UFGS-33 75 00.00 40 (November 2008)
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Preparing Activity: NASA Superseding
UFGS-33 75 00.00 40 (August 2008)
UNIFIED FACILITIES GUIDE SPECIFICATIONS
References are in agreement with UMRL dated January 2009
SECTION 33 75 00.00 40
SWITCHGEAR AND PROTECTION DEVICES
11/08
NOTE: This specification covers the requirements for switchgear and switchboards
of special design or configuration. For primary-unit substations, use Section
26 11 16 SECONDARY UNIT SUBSTATIONS; for motor control centers, use Section
26 24 19.00 40MOTOR CONTROL CENTERS; for power panelboards, use Section
26 24 16.00 40.00 40 PANELBOARDS. Show switchgear/switchboard elevation, dimensions,
devices, instruments, and installation on drawings.
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. Direct them
to the technical proponent of the specification. A listing of technical proponents
, including their organization designation and telephone number, is on the Internet.
Submit recommended changes to a UFGS as a Criteria Change Request (CCR).
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 are automatically 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 1008/A 1008M(2008a) Standard Specification for Steel, Sheet, Cold-Rolled, Carbon, Structural, High-Strength Low-Alloy and High-Strength Low-Alloy with Improved Formability, Solution Hardened, and Bake Hardened][INSTITUTE OF ELECTRICAL AND ELECTRONICS ENGINEERS (IEEE)IEEE C2(2007; Errata 2007; INT 2008) National Electrical Safety CodeIEEE C37.121(1989; R 2006) American National Standard for Switchgear Unit Substations RequirementsIEEE C37.20.1(2002; Addenda A 2005; Addenda B 2006; R 2007) Standard for Metal-Enclosed Low-Voltage Power Circuit-Breaker SwitchgearIEEE C57.12.90(2006) Standard Test Code for Liquid-Immersed Distribution, Power, and Regulating TransformersIEEE Std 4(1995; Amendment A 2001) High Voltage Testing Techniques][NATIONAL FIRE PROTECTION ASSOCIATION (NFPA)NFPA 70(2007; AMD 1 2008) National Electrical Code - 2008 Edition][UNDERWRITERS LABORATORIES (UL)UL 467(2007) Standard for Grounding and Bonding Equipment]1.2 SYSTEM DESCRIPTION
NOTE: If Section 26 00 00.00 20 BASIC ELECTRICAL MATERIALS AND METHODS is not
included in the project specification, insert applicable requirements therefrom,
and delete the following paragraph.
Section 26 00 00.00 20 BASIC ELECTRICAL MATERIALS AND METHODS applies to work specified in this section.
Submit Certificates to verify the qualifications of the Registered Professional Electrical Engineer.
Submit Equipment and Performance Data for electrical equipment consisting of the following:
One-line diagram of electrical equipment and system.
Short-circuit calculations and a table of short-circuit fault currents at critical points in the electrical
system.
Spare Parts Data
Time/current coordination curves on 270 by 380 millimeter 10 1/2 by 15 inch translucent tracing paper
for each relay device.
Table of recommended relay settings.
Submit Equipment Foundation Data for switchgear assemblies that includes plan dimensions of foundations and relative
elevations, equipment weight and operating loads, horizontal and vertical loads, horizontal and vertical clearances
for installation, and size and location of anchor bolts.
1.3 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. Keep submittals 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, use a code of
up to three characters within the submittal tags 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 reviews the submittal for the Government.] Submit the following in
accordance with Section 01 33 00 SUBMITTAL PROCEDURES:
SD-01 Preconstruction Submittals
Submit Switchgear assemblies not energized until recorded test data has been approved by the
Contracting Officer.
SD-02 Shop Drawings
Submit connection diagrams indicating the relations and connections of the following items by
showing the general physical layout of all controls, the interconnection of one system (or portion
of system) with another, and internal tubing, wiring, and other devices.
Switchgear Assemblies
Buses
Switchgear Components
Automatic/Manual Transfer Switch
Space Heaters
Submit fabrication drawings for the following items consisting of fabrication and assembly details
to be performed in the factory.
Switchgear Assemblies
Enclosures
Buses
Switchgear Components
Weatherproof Enclosures
Automatic/Manual Transfer Switch
Space Heaters
Submit Installation Drawings for the switchgear assemblies in accordance with the paragraph
entitled, "Installation," of this section.
SD-03 Product Data
Submit Equipment and Performance Data for electrical equipment in accordance with paragraph
entitled, "System Description," of this section.
Submit Equipment Foundation Data for switchgear assemblies in accordance with paragraph entitled,
"System Description," of this section.
Submit manufacturer's catalog data for the following items:
Switchgear Assemblies
Enclosures
Buses
Switchgear Components
Weatherproof Enclosures
Automatic/Manual Transfer Switch
Space Heaters
SD-06 Test Reports
Submit test reports for the following tests on switchgear assemblies in accordance with the
paragraphs entitled, "Field Testing" and "Relay Settings and Tests," of this section.
Electrical Acceptance Tests
High-Voltage Tests
Current Test
Insulation-Resistance Test
Weatherproof Test
Electrical Current and Voltage Tests
Ratio and Polarity Tests
SD-07 Certificates
Submit Certificates in accordance with paragraph entitled, "System Description," of this section.
SD-08 Manufacturer's Instructions
Submit manufacturer's instructions for the Switchgear Assemblies including special provisions
required to install equipment components and system packages. Provide special notices that
detail impedances, hazards, safety precautions, and installation instructions.
SD-10 Operation and Maintenance Data
Submit Operation and maintenance manuals for the following equipment:
Switchgear Assemblies
Transfer Switches
Space Heaters
1.4 FACTORY TESTING
Make factory tests on transformers and switchgear assemblies in accordance with the applicable provisions of
the referenced standards.
Perform tests on transformers that include resistance measurements of windings, ratio tests, polarity and phase-rotation
tests, no-load loss at rated voltage, excitation current at rated voltage, impedance voltage and load-loss at
rated current, insulation power factor tests, and dielectric tests. Conduct tests in accordance with IEEE C57.12.90
.
Perform tests on switchgear assemblies that include mechanical operational tests, electrical operation and control-wiring
tests, relaying and metering circuit performance tests, and dielectric tests. Conduct tests in accordance with
IEEE Std 4.
1.5 MANUFACTURER QUALIFICATIONS
Provide material and equipment under this specification that is the standard catalog product of a manufacturer
regularly engaged in the manufacture of switchgear assemblies and their component parts and equipment. Provide
equipment that is of the latest standard design for [indoor] [outdoor] service and that has been in repetitive
manufacture for at least [50] [_____] units.
1.6 ENGINEER QUALIFICATIONS
Perform electrical power system's circuit loading requirements and analyses by a professional electrical engineer
registered with the National Society of Professional Engineers (NSPE). Select a professional engineer who has
conducted electrical coordination studies and tests for not less than five projects of comparable size and complexity.
Perform work by or under the direct supervision of the registered professional electrical engineer.
1.6.1 Engineering Services
Select an electrical engineer holding a valid state license as a Professional Engineer in the jurisdiction where
the project is being constructed, and who specializes in relays and coordinating systems associated with electric-power
apparatus for the manufacturer of the equipment, to coordinate all circuit-interrupting devices before the substation
is energized. Duties and responsibilities of the engineer include the following work.
1.6.1.1 Preliminary Survey and System Coordination Study
Review necessary short-circuit calculations to determine the minimum and maximum values of short-circuit current
for faults anywhere in the system. Review values of fault current to be expected at each protective device shown
on the one-line diagrams.
Prepare one-line diagrams that indicate by means of single lines and simplified symbols the course and component
devices of an electric circuit or system of circuits and their electrical characteristics.
Inspect equipment and determine the intended function of each circuit-interrupting device and the manner in which
it is connected to provide a properly coordinated electrical power system under normal load and fault conditions.
Check and compare wiring diagrams furnished by the manufacturer with actual connections of the equipment to verify
that each device is properly connected to perform its intended function.
1.6.1.2 Time/Current Curves and Settings
Plot time/current curves on a single sheet of graph paper or electronic format for those devices that are to
operate selectively in series with each other using a common current scale, with current ratings at the lowest-voltage
level. Plot curves progressively as each circuit is studied, starting with the device farthest from the source.
Make each curve on the graph include tolerance band and show degree of coordination with each successive device.
Coordinate adjustable and nonadjustable protective devices to operate on the minimum current that permits distinguishing
between fault and load current in a minimum amount of time.
Select time and current settings for the adjustable devices that operate in sequence with the nonadjustable devices
to isolate a fault with a minimum of disturbance to the unfaulted portion of the system.
PART 2 PRODUCTS
2.1 EQUIPMENT STANDARDS
Submit Switchgear assemblies that conform to IEEE C37.20.1.
2.2 CONSTRUCTION
2.2.1 Switchgear and Auxiliary Compartments
NOTE: Ability to remove access covers is required for maintenance activities.
In addition, access may be required to inspect this device while circuits are
energized (for example, using infrared imaging). Minimum distances to energized
circuits is specified in OSHA Standards Part 1910.333 (Electrical - Safety-Related
work practices). OSHA Standards are available on the internet.
Stationary mount switchgear assemblies and auxiliary equipment in self-supporting, self-contained, sheet metal
enclosures with front-hinged doors and hinged rear covers. Join sheet metal compartments together to form a
continuous structure. Provide sheet metal barriers, enclosures, and external covers and doors that are constructed
from cold-rolled carbon-steel sheets of commercial quality not less than [1.9] [_____] millimeter [14] [_____]-gage
, with stretcher-level flatness in accordance with ASTM A 1008/A 1008M.
Provide unit sheet metal that encloses one or more vertically mounted power circuit breakers or auxiliary equipment
in individual sheet metal compartments and a full height rear compartment. Provide housing that is approximately
2300 millimeter 90 inches high with individual ventilated [front] [rear]-hinged panels and bolted top and rear
covers. Provide rear compartment that contains the main bus, main bus-tap connections, cable connections, and
instrument transformers.
2.2.2 Compartment Details
Completely wire compartments with cable terminals, cable clamps, control bus, control power switch, and terminal
blocks. Provide terminal blocks that are readily accessible for the external connections of metal-clad switchgear.
Run low-voltage wiring for controls and accessories to terminal blocks having numbered points, as indicated,
to identify circuits. Run low-voltage wiring in conduit or wiring raceways to isolate the wiring from high-voltage
circuits. Identify wiring connections.
Identify each compartment of the switchgear assembly by an identification plate engraved with circuit and function
designations.
Provide removable elements of the same type and rating in the switchgear assembly that are physically and electrically
interchangeable in corresponding compartments. Provide front-hinged panel that is suitable for mounting instruments,
relays, control switches, and indicating lamps.
Provide barriers between a sectionalized bus with bus sectionalizing breakers in a compartment that are sheet
steel not less than [3.1] [_____] millimeter [11] [_____] gage. Provide other covers, barriers, panels, and
doors that are not less than [1.9] [_____] millimeter [14] [_____] gage.
Reinforce each compartment with structural members and weld together. Ground welds to a smooth flat surface
before painting.
2.2.3 Buses
Completely bus switchgear assemblies utilizing electrical grade, high conductivity, solid copper bus bar having
a rectangular cross section. Uniformly position and phase sequence, riser and bus tap connections in accordance
with IEEE C37.20.1. Support and brace buses to withstand both electrically and mechanically the short circuit
current ratings.
Silverplate termination and connection points by an electroplating process for all bus bar used in the switchgear.
Silver coating methods that do not use the flow of electrical current as part of the process are not acceptable.
After plating, do not sand or otherwise abrade the contact surface, but clean it with a soft cloth immediately
prior to final assembly.
Make all bus bar connections using silicon bronze bolts with wide flat silicon bronze washers under the bolt
head and nut. Tighten and check these connections by use of a calibrated torque wrench. Other connection designs
are allowed with the written agreement of the Contracting Officer.
[Provide main bus that is readily accessible for connection of future switchgear assemblies at either end. Provide
main and auxiliary control drawout type connections that are silver-to-silver contact, positive pressure, self-aligning,
with enclosure-to-enclosure stationary mechanism when breaker is in drawout position.]
Provide voltage rating and insulation level of switchgear assemblies as specified and that conform to IEEE C37.20.1
.
Provide temperature limits for buses and bus-tap connections in switchgear assemblies that are in accordance
with IEEE C37.20.1.
Provide a continuous rigid copper ground bus that extends throughout the entire assembly and that grounds the
stationary structure and equipment. Provide ground bus that is capable of carrying the rated short circuit current
of the protective devices in the switchgear assembly for a minimum period of one second.
Completely wire compartments with cable terminals, cable clamps, control bus, control power switch, and terminal
blocks. Provide terminal blocks that are readily accessible for the external connections of metal-clad switchgear.
Run low-voltage wiring for controls and accessories to terminal blocks having numbered points, as indicated,
to identify circuits. Run low-voltage wiring in conduit or wiring raceways to isolate the wiring from high-voltage
circuits. Identify wiring connections.
Identify each compartment of the switchgear assembly by an identification plate engraved with circuit and function
designations.
NOTE: Delete the following paragraphs when the switchgear units are not bus
connected.
Provide metal-enclosed bus of non-segregated group phase construction that includes rigid insulated conductors
and supports in a grounded metal enclosure with associated ventilation and space-heater enclosures, condensation
barriers, expansion and connection joints, and fittings in accordance with IEEE C37.20.1.
Completely bus Enclosures with an insulated solid rigid copper bus bar of rectangular cross section. Uniformly
position and phase sequence bar and connections within the enclosure for adaptation to metal-clad switchgear
assemblies and power transformers, in accordance with IEEE C37.20.1.
Support and brace bus bar to withstand short-circuit stresses with momentary current ratings, in accordance with
IEEE C37.20.1. Silverplate and bolt together contact surfaces of all bus connections to ensure maximum conductivity.
Provide voltage and current ratings that conform to IEEE C37.20.1.
Provide insulating supports that consist of track-resistant, flame-retardant IEEE Class 130 electrical insulating
materials. Provide voltage rating and insulation level that conform to IEEE C37.20.1.
Provide sheet metal weatherproof enclosures that are constructed from carbon steel sheets of commercial quality,
not less than [1.9] [_____] millimeter [14] [_____] gage. Reinforce each section with structural members and
bolt together. Structurally support complete assembly as indicated.
2.2.4 Switchgear Assemblies
Provide general arrangement of the number of compartments and each compartment's components as shown.
[Provide bus sectionalizing switchgear compartments that include a metal-enclosed low-voltage power circuit breaker.]
[Provide secondary feeder switchgear compartments that include the following equipment:
[Metal-enclosed low-voltage power circuit breaker]
[Provisions for terminating cables of the metal-enclosed bus]]
[Provide auxiliary station power compartments that include the following:
[Control-power transformer and primary fuses]
[Circuit overload protection]
[Potential transformers for relaying purposes]
[Lamp ground detectors]
[Batteries and battery charger]
[Circuit breaker control transformer]]
[Provide auxiliary metering compartments that include the following:
[Current transformers]
[Ammeters and ammeter switches]
[Potential transformers]
[Voltmeters and voltmeter switches]
[Watt-hour meters]
[Reverse current directional relays]
[Lamp ground detectors]]
[Cooling fans]
[Provide auxiliary bus sectionalizing compartments that include a contactor for automatic transfer of control
power and auxiliary devices.]
[Provide switchgear compartments for future use that are fully equipped to receive the removable element with
complete bus connections, disconnecting devices, rails, and cell interlocks.]
[Provide filler compartments incidental to the switchgear assembly that are empty compartments with hinged cover
plates.]
[Provide main and feeder power circuit breakers that are suitable for fully rated [nonselective] [selective]
trip systems in accordance with IEEE C37.121.]
2.2.5 Weatherproof Construction
Provide switchgear assemblies for outdoor applications that are weatherproof NEMA Type 3R enclosures, with ventilated
[front] [and rear]-hinged doors, base, and roof sections. Provide flanged access doors that close against rubber
or similar gasketing material. Provide ventilated openings with filtered covers and screened vents for protection
against the weather and insects. Equip doors with latch, stops, and door-locking mechanism.
Provide roof section that is unit construction with removable sloping cover and overhanging roof drip edge.
Provide base section that is unit construction and that supports metal-enclosed switchgear [150] [_____] millimeter
[six] [_____] inches above the concrete foundation.
[Provide switchgear enclosures that include a removable steel floor plate which is drilled for conduit and cable
during installation. Undercoat floor and roof of the switchgear with a heavy rubberized protective sealing material
at least [0.79] [_____] millimeter [1/32] [_____] inch thick.]
[Equip each enclosure subject to an outside or humid environment with thermostatically controlled electric space
heaters and cooling fans to minimize condensation. Make provisions for terminating incoming and outgoing underground
cables.]
2.3 SWITCHGEAR COMPONENTS
2.3.1 Air Interrupter Switches
Provide the manually group-operated three-pole, gang-operated, stationary type air interrupter switches in accordance
with IEEE C37.121 and IEEE C37.20.1, that carry the rated current continuously.
Provide stored energy type quick-make/quick-break operating mechanism with positive action for fault closing
and load-interrupting capability. Provide a handle speed that is independent of operation.
[Provide the stored energy type operator, designed for easy inspection with a basic impulse level (BIL) of [95
at 14.4 kilovolts] [110 at 35 kilovolts]. Mechanically interlock access door with a switch mechanism. Provide
[2.7] [_____] millimeter [12] [_____]-gage minimum sheet steel switch enclosure. Provide switch gear to switch
connections that prevent ground transmission to switch.]
[Make provision for terminating underground cables and for bus connections to the primary of the transformer
transition box. Use flexible connections between primary potheads and the interrupter switch with adequate bracing
provided for short circuit stresses.]
Provide switch that has provisions for padlocking in the open and closed positions. Clearly and permanently
mark open and closed switch positions on the outside of the enclosure. Provide a mechanical indicator that shows
the switch position.
Provide switch that has provision to add electrical operation with auxiliary contacts, and that is [two-position,
single-throw] [duplex dual feeders] [selector] type.
[Equip interrupter switchgear with three current-limiting [CLE type] [RBA boric acid] power fuses capable of
interrupting the available short circuit current with switch carrying full load rated current. Provide a mechanical
interlock to prevent access to the power fuses when the interrupter switch is closed.]
2.3.2 Power Circuit Breakers
Provide air circuit breakers of the [manually] [electrically] operated type as indicated, conforming to Section
26 05 70.00 40 HIGH-VOLTAGE OVERCURRENT PROTECTIVE DEVICES and Section 26 05 71.00 40 LOW-VOLTAGE OVERCURRENT
PROTECTIVE DEVICES.
2.3.3 Molded-Case Circuit Breakers
Provide molded-case circuit breakers that conform to Section 26 05 70.00 40.00 40 HIGH-VOLTAGE OVERCURRENT PROTECTIVE
DEVICES and Section 26 05 71.00 40 LOW-VOLTAGE OVERCURRENT PROTECTIVE DEVICES.
2.3.4 Instruments and Instrument Transformers
Provide indicating instruments, protective relays, current and potential transformers, instrument transfer switches
, and control-power transformers that conform to the applicable requirements of Section 26 05 70.00 40.00 40
HIGH-VOLTAGE OVERCURRENT PROTECTIVE DEVICES and Section 26 05 71.00 40 LOW-VOLTAGE OVERCURRENT PROTECTIVE DEVICES.
2.3.5 Control-Power Circuit Overcurrent Protection
Provide branch-circuit breakers that provide circuit overload protection to compartment heater, lights, convenience
outlets, transformer fans, and other devices.
2.3.6 Automatic/Manual Transfer Switch
Provide the rotary snap-action type automatic/manual transfer switch with silver-plated contacts. Provide a
manually operated two-position transfer switch device designed to interrupt the automatic transfer and close-back
features of the system when the transfer switch is in the manual position. Provide a switch that permits the
transfer of all load to a particular switchgear assembly without a service interruption when the transfer switch
is in the automatic position.
2.3.7 Control-Power Circuit Contactor
Provide a contactor for automatic transfer of control-power that is designed for 120/240-volt, single-phase,
60-Hz service with current rating. Provide contactor that is the open type, two-pole, double-throw with solid
neutral connections and that automatically transfers its load circuits to the alternate power supply upon loss
of power in the normal supply. Provide a device that is electrically operated and mechanically held and that
obtains its operating current from the source to which the load is transferred. Provide contactors for automatic
transfer of control power that is suitable for installation in metal-clad switchgear.
2.3.8 Service and Maintenance Devices
Include the following service and maintenance devices as a part of the substations:
A manual handle for operating the air and power circuit breaker isolating mechanism
Removable manual maintenance closing devices for air and power circuit breakers
Transfer trucks for air and power circuit breakers
Facilities for operating air and power circuit breakers in the test or removed position
Facilities for withdrawing air and power circuit breakers for inspection or maintenance
Test plugs and cable for meters and relays
2.3.9 Protective Relays and Devices
Provide protective relays and devices that comply with Section 26 05 70.00 40.00 40 HIGH-VOLTAGE OVERCURRENT
PROTECTIVE DEVICES and Section 26 05 71.00 40 LOW-VOLTAGE OVERCURRENT PROTECTIVE DEVICES.
2.4 AUTOMATIC/MANUAL TRANSFER SWITCH
Make provision for the automatic transfer of load on loss of voltage, low voltage, single phasing, reverse phase
rotation of either source, and the automatic transfer of load upon restoration of normal service without a service
interruption. Under normal operation, close both main secondary breakers with the main bus tie breaker open
and the automatic/manual transfer control switch in the automatic position, and energize and load each source
of supply.
Electrically operate main and bus tie breakers with remote pushbutton controls electrically interlocked so that
only two of the three breakers close by operation of the respective breaker-closing mechanisms when the automatic/manual
transfer control switch is in the manual position.
Provide main secondary breaker compartments that include undervoltage and phase-sequence relays with adjustable
time-delay between 30 and 200 cycles.
Provide auxiliary relays that automatically open the proper main secondary breaker and close the main bus tie
breaker under fault conditions. Include provisions for the automatic reclosing of the main secondary breakers
before opening the main bus tie breaker when normal service is restored.
Provide lockout relays that prevent automatic transfer of load from undervoltage caused by overload or transient
conditions. Provide lockout relay controls that are connected into the closing circuit of the main tie breaker
to prevent operation under lockout conditions and that are the hand-reset type.
Provide main bus tie breaker compartment that includes an automatic/manual transfer switch which disconnects
the automatic transfer features when in the manual position. Provide main secondary and bus tie breakers that
are manually inoperable when the automatic/manual transfer control switch is in the automatic position.
Provide a bypass switch to permit manual momentary paralleling of the two sources of supply in restoring normal
service without interruption.
Provide main secondary and bus tie breakers that are manually operable when the automatic/manual transfer control
switch is in the manual position.
Provide a contactor for the automatic transfer of control power. Provide control power transformers that capable
of furnishing power through the selective contactor for the bus tie breaker, feeder breakers, compartment heaters,
interior lighting, utility outlets, battery chargers, and other miscellaneous equipment.
Supply secondary switchgear assembly or assemblies from two separate sources, with each source normally carrying
load as indicated. Under normal operation, close both main secondary breakers with the main bus tie breaker
open. Do not operate two sources of supply in parallel.
2.5 PAINTING
NOTE: For all outdoor applications and all indoor applications in a harsh environment
refer to Section 09 96 00 HIGH-PERFORMANCE COATINGS. High performance coatings
are specified for all outdoor applications because ultraviolet radiation breaks
down most standard coatings, causing a phenomena known as chalking, which is
the first stage of the corrosion process. For additional information contact
The Coatings Industry Alliance, specific suppliers such as Keeler and Long and
PPG, and NACE International (NACE).
After fabrication, prepare and paint exposed ferrous-metal surfaces of switchgear assemblies and component equipment.
Provide standard finish by the manufacturer on assemblies and component equipment when used for most indoor installations.
For harsh indoor environments (any area subjected to chemical and/or abrasive action), and all outdoor installations,
refer to Section 09 96 00 HIGH-PERFORMANCE COATINGS.
2.6 SPACE HEATERS
NOTE: Include the following paragraphs for outdoor switchgear assemblies and
indoor assemblies which are in humid environments. Provide space heaters to
prevent moisture build-up in ventilated compartments.
wattage supplied by heaters is one-fourth of heater nameplate rating when 240-volt
heaters are operated at 120 volts.
Equip each section of the switchgear assembly with externally energized space heaters to provide approximately
40 watts per square meter 4 watts per square foot of outer surface area. Provide heaters that have a power
density that does not exceed 4 watts per 650 square millimeter per square inch of heater element surface. Provide
heaters that are rated at 240 volts for connection to 120 volts. Locate heaters at the lowest portion of each
space to be heated. Cover terminals. Use thermostats to regulate the temperature.
Provide heaters that are installed and operable at the time of shipment so that the heaters can be operated immediately
upon arrival at the site, during storage, or before installation. Provide connection locations that are marked
prominently on drawings and shipping covers and that have temporary leads for storage operation. Make leads
easily accessible without having to remove shipping protection.
2.7 EXTERNAL VOLTAGE SOURCE
Provide externally powered wiring to the switch that is grouped together as much as possible and connected to
a terminal block which is marked with a laminated plastic nameplate having 5 millimeter 3/16 inch high white
letters on a red background as follows:
DANGER - EXTERNAL VOLTAGE SOURCE
Provide externally powered wiring that includes 120-volt unit space heaters.
PART 3 EXECUTION
3.1 INSTALLATION
Make installation conform to IEEE C2 and NFPA 70.
Electrically and mechanically connect complete assembly together at the site from coordinated subassemblies shipped
in complete sections from the manufacturer. Provide installation that is carefully aligned, leveled, and secured
to the foundation and that conforms to the manufacturer's recommendations.
Provide noncurrent carrying parts and enclosures of the switchgear that are bonded together and grounded to the
ground grid with a maximum resistance to ground of 20 ohms. Exothermically weld inaccessible ground connections
in accordance with UL 467. The minimum size of ground conductor is 11.7 millimeter diameter 4/0 AWG.
NOTE: The following applies to high-voltage switchgear only.
Provide switchgear with an earth ground resistance pad as shown on the drawings. Provide a switchgear resistance
to ground that does not exceed the following values:
5,000 kVA and above 3 ohms
5,000 kVA and below 5 ohms
Provide switchgear assemblies separated for shipping that are carefully joined to present a neat appearance with
main and ground bus joints that are tightened to manufacturer's recommended torque values. Handle assemblies
with lifting devices.
Submit Installation Drawings for the switchgear assemblies. Provide drawings that include complete details of
equipment layout and design.
3.2 FIELD TESTING
Subject main bus of switchgear assemblies to insulation resistance and high-voltage, 60-hertz withstand tests
after installation is completed and ready for operation. Perform Electrical current and voltage tests in accordance
with referenced standards in this section.
Provide test equipment, labor, and technical assistance to perform the electrical acceptance tests as herein
specified.
Disconnect incoming section main bus from the power supply and primary feeder cables, and ground the switchgear
enclosure before the insulation and high-voltage tests are conducted.
Disconnect outgoing section main bus from the secondary feeder cables and from the power supply and primary feeder
cables. Ground switchgear enclosure before conducting insulation and high-voltage tests.
Give the main bus of the incoming section an insulation-resistance test with a [5,000] [2,500]-volt insulation-resistance
test set.
Give the main bus of the outgoing section an insulation-resistance test with a [1,000] [2,500] [500]-volt insulation-resistance
test set.
Apply test for not less than five minutes and until three equal consecutive readings, one minute apart, are obtained.
Record readings every 30 seconds during the first two minutes and every minute thereafter. Minimum acceptable
resistance reading is 100 megohms.
Upon satisfactory completion of the insulation-resistance test, subject the main bus to a high-voltage (hi-pot)
withstand test. Provide test voltage that is equal to [100 percent for 60 Hz] [75 percent for dc] of the values
shown in IEEE C37.20.1 for metal-clad switchgear and metal-enclosed low-voltage power-circuit-breaker switchgear.
Apply test for one minute.
Upon satisfactory completion of the high-voltage withstand test, give the main bus a second insulation-resistance
test as before. Results of the second test are required to be within five percent of the first test and indicate
no evidence of permanent injury by the high-potential test.
Subject weatherproof enclosure and switchgear assembly to a weatherproof test conducted at the site in the presence
of the Contracting Officer in accordance with IEEE C37.20.1.
Provide tests on switchgear assemblies that include electrical and mechanical operational tests, control-wiring
tests, relaying and metering circuit performance tests, and dielectric tests. Conduct tests in accordance with
IEEE Std 4.
Final acceptance depends upon the satisfactory performance of the equipment under test. Provide final test data
to the Contracting Officer. Provide data with a cover letter/sheet clearly marked with the System name, Date,
and the words "Final Test Data - Forward to the Systems Engineer/Condition Monitoring Office/Predictive Testing
Group for inclusion in the Maintenance Database."
3.3 RELAY SETTINGS AND TESTS
Properly coordinate circuit-interrupting devices before the switchgear assemblies are energized. Thoroughly
inspect and adjust relays at the site in the presence of and at the discretion of the Contracting Officer.
3.4 PRELIMINARY INSPECTION
Conduct preliminary inspection of electrical equipment. Make relay settings and tests only after the preliminary
survey and system coordination survey have been completed. Provide preliminary inspection, relay settings, and
tests as follows:
Inspect equipment for damage or maladjustment caused by shipment or installation. Remove wedges, ties,
blocks, and other packing material installed by manufacturer to prevent damage in shipment.
Verify protective relays, auxiliary relays, trip coils, trip circuit seal-in and target coils, fuses,
and instrument transformers to be of the proper type and range.
Perform electrical continuity tests on current, potential, and control circuits.
Perform Ratio and polarity tests on current and potential transformers.
Perform insulation tests on relays, wiring, instrument-transformer secondary windings, and instruments.
Remove each adjustable relay from its case and calibrated separately as an instrument, using a variable alternating-current
source and an accurate timing device. Verify with this procedure that the relay has not been damaged in shipment
and that it performs in accordance with previously prepared time-current coordination curves at specified current
tap and time dial settings.
With the relay disconnected and the main current transformer effectively open, apply a current test to the remainder
of the secondary circuit to detect any open or short-circuit connections.
Reinstall and connect relays into their current-transformer secondary and control circuits.
Report any defects in electrical equipment, protective devices, wiring, or other conditions that prevent complete
coordination and the successful operation of equipment to the Contracting Officer before proceeding with the
work.
After the installation has been thoroughly tested and certified to be in satisfactory condition, with relays
calibrated and adjusted to the proper current tap and time dial setting, request permission to energize the equipment
at system voltage for final testing.
3.5 ENERGIZING SWITCHGEAR ASSEMBLIES
NOTE: When required by the project, replace the following paragraphs with the
statement "Switchgear assemblies will be energized by Government personnel."
Do not energize switchgear assembly until it is completely installed, tested, approved by the Contracting Officer,
and ready for operation. Conduct site testing and obtain approval from the Contracting Officer.
Using ammeter, voltmeter, and wattmeter or phase-angle meter, measure and compare the values and polarities of
voltage and current with those expected in the various relay circuits. Inspect and note positions of directional
elements and the voltage relays.
After inspection and satisfactory tests have been completed on all active relay circuits under a no-load condition,
give each relay an operational test with diverted load currents or simulated ground faults.
Prepare a report with records of connections, electrical constants, settings, test values, operating performance,
and failures or weaknesses found on test.
Perform tests and procedures for testing in accordance with the manufacturer's recommendations, as approved by
the Contracting Officer. Provide final test reports to the Contracting Officer. Provide reports with a cover
letter/sheet clearly marked with the System name, Date, and the words "Final Test Reports - Forward to the Systems
Engineer/Condition Monitoring Office/Predictive Testing Group for inclusion in the Maintenance Database."