Download medium-voltage switchgear

SECTION [26 13 16] [16341]
MEDIUM-VOLTAGE FUSIBLE INTERRUPTER SWITCHGEAR
(AIR-INSULATED)
PART 1 - GENERAL
1.1
SCOPE
A.
1.2
This specification defines the technical requirements for indoor or outdoor type, air-insulated
switchgear (AIS) that is equipped with a three position load break SF6 switches rated 4.76 kV,
8.25kV, 15 kV and 27 kV, up to 125kV BIL, for use on a nominal system voltage of up to
26.4kV. This specification covers the design, manufacture, factory production testing, and field
service assistance during installation and commissioning of SF6 Load Interrupter Switchgear
and associated equipment.
RELATED DOCUMENTS
A.
1.3
Drawings and general provisions of the Contract, including General and Supplementary
Conditions and Division 1 Specification Sections, apply to this Section.
SUBMITTALS
A.
Submit shop drawings and product data for approval and final documentation in the quantities
listed in the data sheet. All transmittals shall be identified by purchaser name, purchaser
location and purchaser order number.
B.
Documents for Approval:
1.
General arrangement drawing showing dimensioned elevation and floor plan, side views,
foundation details and one-line diagram
2.
Panel arrangement drawing showing layout of devices on the panel doors
3.
One line diagrams
4.
Schematics
5.
Nameplate engraving drawings
6.
Bill of material
C.
Final Documents: Record documentation to include:
1.
Documents listed above in 1.3.B
2.
Wiring diagrams
3.
Recommended spare parts list for start-up support
4.
Instruction manual
D.
Product Data: Include features, characteristics and ratings of individual load interrupter switches
and other components. Provide time-current characteristic curves for overcurrent protective
devices on request, including fusible devices.
E.
Shop Drawings: Detail equipment assemblies and indicate dimensions, weights, required
clearances, method of field assembly, components and location and size of each field
connection. Include the following:
1.
Nameplate legends.
2.
Bus configuration with size and number of conductors in each bus run, including phase
and ground conductors of main and branch buses.
3.
Current ratings of buses.
4.
Short-time and short-circuit ratings of switchgear assembly.
5.
Wiring Diagrams: Detail wiring for power, signal and control systems including
differentiation between manufacturer-installed and field-installed wiring.
1.4
RELATED STANDARDS
A.
Comply with requirements of latest revisions of applicable industry standards, specifically
including the following:
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1.
2.
3.
1.5
AIS Metal Enclosed Load Interrupter Switchgear:
a.
ANSI C37.20.3 Standard for Metal-Enclosed Interrupter Switchgear
b.
ANSI C37.20.4 Indoor AC Switches for Use in Metal-Enclosed Switchgear
c.
ANSI C37.22 Preferred Rating and Related Required Capabilities for Indoor AC
Medium-Voltage Switches Used in Metal Enclosed Switchgear
d.
ANSI C37.57 Metal-Enclosed Interrupter Switchgear Assemblies -- Conformance
Testing
e.
ANSI C37.58 Indoor AC Switches for Use in Metal-Enclosed Switchgear –
Conformance Test Procedures
f.
[ANSI C37.81 - Seismic Test]
g.
ANSI C57.13 Standard Requirements for Transformers
h.
IEC 60420 High voltage alternating current switch-fuse combinations (Test
duties 4 and 5)
i.
UL / cUL Listed Underwriters Laboratories
Current Transformers
a.
IEEE C57.13 Requirements for Instrument Transformers
b.
IEC 60044-1 Current Transformers
c.
IEC 60044-7 Electronic Current Transformers
Voltage Transformers
a.
IEEE C57.13 Requirements for Instrument Transformers
b.
IEC 60044-2 Voltage Transformers
c.
IEC 60044-8 Electronic Voltage Transformers
QUALITY ASSURANCE
A.
1.6
Manufacturer Qualifications: Engage a firm with at least 5 years experience in manufacturing
switchgear. The manufacturer of the switchgear assembly shall also manufacture the load
interrupter switches.
DELIVERY, STORAGE AND HANDLING
A.
Deliver in convenient shipping groups. Shipping groups shall not exceed 8 ft. in length.
B.
Shipping groups shall be shipped fully assembled.
accessories.
C.
Outdoor Walk-in single aisle switchgear or non-walk-in shall be shipped fully assembled except
for necessary shipping splits for transportation and handling.
D.
A cabinet shall be provided for storage of small accessories. This cabinet shall be installed on
one end of the switchgear for indoor installations, or for outdoor installations, shipped loose for
mounting on a wall in the vicinity of the switchgear
Fuses will be shipped as part of the
PART 2 - PRODUCTS
2.1
MANUFACTURERS
A.
2.2
[The metal-enclosed switchgear assembly shall be SIMOSEC manufactured by Siemens
or pre-approved equal. Approved manufacturers are as follows:
1.
SIEMENS
2.
. ]
RATINGS
A.
System Configuration: Switchgear suitable for application in three-phase, 60-Hz, groundedneutral system.
B.
Electrical Ratings:
1.
Nominal System Voltage, kV: Up to 26.4
2.
Maximum Design Voltage, kV:[5] [15] [27]
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3.
4.
5.
6.
7.
2.3
Rated Main Bus Current, A: [600] [1200]
Rated Interrupting (Short-Circuit) Current, kA Symmetrical: [20] [25]
Rated Short-Time Current, kA (3 Second): [20] [25]
Rated Power-Frequency Withstand Voltage, kV (1 Minute): 50
Rated Impulse Withstand Voltage, kV BIL: [60] [95] [125]
GENERAL REQUIREMENTS
A.
The air-insulated load interrupter switch switchgear shall be metal-enclosed as defined in IEC
60420 (62271-105) and ANSI C37.20.3. All components of the switchgear (i.e., load interrupter
switches, busbar, grounding switches, VT’s etc.) shall be in grounded metal enclosures. The
construction shall withstand forces (repeatedly, without distortion) caused by closing and
opening of the load interrupter switch. The switchgear shall be capable of sustaining, without
damage, all of the stresses produced by fault conditions up to and including the rated shortcircuit current.
B.
Each current carrying component of the equipment shall be capable of continuous operation at
the specified ratings without exceeding the maximum temperature rise stated in the ANSI and
IEC standards.
C.
Each switchgear panel shall be designed and manufactured with provision for future expansion
on each end, unless the particular lineup configuration precludes extension.
D.
The enclosures housing the primary (medium voltage) components shall be constructed of
sheet metal. Ferrous metal components shall be finished with electrostatically applied paint
finish in manufacturer’s standard light gray color or galvanized. Mechanism parts not suitable for
painting shall be plated for corrosion resistance.
E.
The medium voltage enclosure shall be factory assembled and modular in design. The load
interrupter switch enclosure shall be hermetically sealed.
F.
The switchgear shall be designed so that normal service, inspection, maintenance, grounding of
high voltage cables and elimination of electrostatic charges can be carried out safely, with
adjacent sections energized.
G.
A continuous ground bus shall run the length of the switchgear group for reliable grounding.
Each feeder section’s housing must be connected to the switchgear ground bus.
H.
Conductors and connectors for the busbars shall be copper, designed to carry continuous
current and shall withstand specified symmetrical short-circuit current. The surfaces of the
conductors shall have a smooth finish to prevent any electrical discharges. Load interrupter and
ground switch contacts shall be silver-plated to provide high conductivity.
I.
The connection points between busbars and/or components shall be easily accessible to allow
assembly and testing to be accomplished without major disassembly.
J.
All cable accessible compartments shall be interlocked so that they can be opened only when
the power is off and the switch is in the grounded position.
K.
The front of each switchgear section shall consist of three (3) separate compartments for the
following main components:
1.
Low voltage compartment for controls located in the top compartment. Terminal blocks,
CT connections, VT connections and miscellaneous control devices shall also be located
in this compartment. Connection terminal blocks for external connections will be located
in this compartment. Operation of the switchgear shall not be affected by opening any of
the low voltage compartment doors.
2.
Load Interrupter Switch operating mechanism, located in the middle compartment, with
all serviceable items accessible from the front.
3.
The lower compartment shall be available for mounting CT’s, VT’s, Surge Arresters and
cable termination.
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L.
Each section shall have a mimic diagram of sufficient size and color contrast to be plainly visible
to an operator. Mimic diagrams shall show interrupter switches, grounding switches, power
fuses, CT’s and busbar connections. Busbar VTs or busbar cable connections shall also be
shown. The mimic diagram shall be on the front of each section, in conjunction with the
mechanical position indicators.
M.
Stainless Steel Gas Vessel: The vessel housing the load interrupter switch shall be housed in a
laser welded stainless steel gas vessel. It shall be hermetically sealed without means of adding
or removing gas. Sulfur Hexafluoride (SF6) gas shall be installed in the vessel for the
interrupting medium. Cast resin insulating materials shall be employed for the insulation of
primary conductors of each phase from the grounded metal-enclosure. Solid insulators shall be
non-hygroscopic, epoxy cast resin, free from voids and contaminants. The contour of the
insulators shall be such that a uniform voltage gradient is produced over the entire surface. The
bushing-type insulators will support the live conductors and (where necessary) provide a gas
tight barrier between the vessel and air.
N.
Gas Monitoring: The gas vessel shall be provided with a gas level indicator. Dry contacts
provided on the indicator shall change state if the pressure falls below preset limits. [The
contacts shall be factory wired to prevent operation of the switch if the gas pressure has
fallen below the preset limits.]
O.
Visible Disconnect: A visible disconnect is required to meet the NEC. A viewing window at least
3 inches across shall be provided in order to determine the position of the switch blades.
P.
[PICK AN ENCLOSURE TYPE. DELETE THE OTHER 2]
Q.
[NEMA 1]
R.
[NEMA 3R Non-Walk In]
S.
[NEMA3R - Outdoor Walk-in Single Aisle. This design shall consist of indoor type
switchgear located inside a weatherproof steel housing having an operating aisle space
of sufficient size to permit load interrupter switch inspection, test and maintenance.
Included shall be the following:
1.
Outdoor enclosure: Painted steel weatherproof construction; integral structuralsteel base frame with factory-applied asphalt undercoating; and equipped with the
following features:
a.
Structural design and anchorage adequate to resist loads imposed by
125mph wind.
b.
Adequate Fluorescent aisle lights with low-temperature ballasts, controlled
by a three-way wall switch at each access door.
c.
Space heater operating at one-half rated voltage and sized to provide
condensation.
d.
Louvers equipped with insect/rodent screen and filter and arranged to permit
air circulation while excluding exterior dust and rodents.
e.
Aisle access doors at each end with outside padlocking provisions and
interior panic latches.
f.
Two duplex receptacles with integral ground fault protection, one at each
aisle access door.
g.
[Aisle heaters and exhaust fans thermostatically controlled as required.]
h.
[Thermally insulated walls for better heating and cooling performance.]
i.
[HVAC unit.]]
2.4
LOAD INTERRUPTING AND GROUNDING SWITCH
A.
The Load Interrupting and Grounding Switches (three position switches) shall be located in a
stainless steel gas vessel. The three position switch shall be capable of 1000 mechanical
operations and 100 full load break operations. It shall be rated for a minimum of 600A.
B.
It shall not be possible to switch directly from Connected to Grounded position. A mechanical
interlock shall prohibit simultaneous access to manual load interrupter and grounding switch
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operators. The grounding position shall allow for safely grounding the feeder circuit by
grounding the cable side of the switch. The ratings of the three position switch shall be
coordinated with the system ratings. Means shall be provided to allow for visual confirmation of
the switch position from the front of the switchgear. The switch positions shall be clearly visible.
If view windows are furnished, they shall be accessible without opening any access doors. This
provision shall be available for use with the switchgear energized. All operations shall be
performed without requiring the opening of any doors. [The operating handle shall operate
the switch through a stainless steel bellow, eliminating the need for moving seals.
Rotary handles are not permitted.]
C.
The manually operated mechanism for the three position switch shall require one operating
handle for changing the switch position from the closed to open position. A different handle
shall be required for changing the switch position from open to grounded position. A
mechanism operated position indicator shall be located on the front of the switchgear panel and
indicate CLOSED, OPEN and EARTH (grounded).
D.
The operating mechanism shall be provided with the following control features:
1.
Local, manual operation of the three position switch, utilizing two separate operating
handles, provided as accessories.
2.
If an electrically operated mechanism is provided, manual operation shall block electrical
operation. The operating mechanism shall allow local and remote electrical operation of
the load interrupting switch with automatic cutoff when switch has reached complete
travel between positions.
3.
Auxiliary switches as required for interlocking and remote indication.
4.
The position of the switches shall be visible according to NEC.
E.
Where two switching devices require interlocking, the interlocks shall be designed to prohibit
simultaneous operation of the devices. The interlock system shall prevent either device from
being blocked in an intermediate or undefined position. The system shall operate effectively for
either electrical switching commands or manual switching commands.
2.5
CURRENT TRANSFORMERS
A.
Current Transformers shall be available for use with AIS Medium Voltage Switchgear.
B.
Each load interrupter switch shall be capable of having a low voltage CT installed around the
cast resin bushing, free of dielectric stress.
C.
Each load interrupter switch shall be capable of having one set of CTs.
D.
Each tie switch shall be capable of having one set of CTs.
E.
All current transformers shall be installed around feeder cables so that the CT is free of
dielectric and thermal stress. CT’s shall be located on the cable termination side of the
interrupter switch.
F.
Current transformers shall be single ratio (SR) as shown on the contract drawings and shall
have a short-circuit rating not less than that of the associated switchgear. Standard current
transformers are rated 600:5, C100 accuracy. They shall be capable of carrying the rated
primary current for a period of one minute with the secondary windings open-circuited as
specified in IEEE C57.13 or related IEC 60044-1 standards.
G.
Low power signal CTs shall also be acceptable.
2.6
VOLTAGE TRANSFORMERS
A.
Voltage transformer ratings and locations shall be as indicated on the drawings. They shall
comply with the requirements of this section. Voltage Transformers (VT) shall be according to
IEEE C57.13 or related IEC 60044-2 Standards.
B.
Busbar Voltage Transformers: Single-phase, inductive voltage transformers shall be housed in
compartments insulated by air and mounted in appropriate enclosure.
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C.
Each busbar voltage transformer shall be primary fused (current limiting type) to prohibit the
possibility of transfer of a busbar voltage transformer failure to the corresponding busbar. The
current limiting-fuses shall be located in compartment insulated by air.
D.
The busbar voltage transformers shall be equipped with a 3-position switch (closed-opengrounded) to allow for maintenance on the busbar voltage transformer or fuses without deenergizing the switchgear.
E.
All secondary leads shall be wired to a molded case circuit breaker, located in a corresponding
low voltage compartment.
F.
Low power signal VT’s are also acceptable. If furnished, primary current-limiting fuses and
disconnect switches for the VTs are not required.
2.7
CABLE TERMINATIONS
A.
The number of cables, size and type for each incoming and outgoing feeder shall be shown on
the drawings or provided as an Appendix to this specification.
B.
Cable preparation and termination shall be the responsibility of the buyer or the buyer’s
installing contractor.
2.8
[METERING AND RELAYING
A.
2.9
Multifunction Digital-Metering Monitors shall be UL-listed or -recognized,
microprocessor-based unit suitable for three- or four-wire systems. Units shall be
mounted in the low voltage compartment door.]
[DC BATTERY SYSTEM
A.
DC control power shall be provided by [the switchgear manufacturer] [XXX Company].
The [48] [125] VDC battery system shall be mounted external from the switchgear as
specified below. The battery system should be sized to carry the switchgear continuous
load for 8 hours after loss of charger output and in addition, shall be capable of
operating all control components and switch operations twice at the end of the period.
For purposes of this requirement, a maximum of all of the medium voltage electrically
operated load interrupter switches will be operated simultaneously.
1.
Battery: Lead-calcium type in sealed, complete with electrolyte, fully charged and
arranged for shipment with electrolyte in cells. Each container weighs not more
than 70 lb (32 kg) and contains not more than three cells. Batteries are suitable for
service at an ambient temperature ranging from -18 to +25 deg. C.
2.
Rack: Provide a two-step rack that fits available space indicated. Batteries shall be
provided with necessary electrical connections between cells and between rows of
cells and include two flexible connectors with bolted-type terminals for output
leads.
3.
Accessories: Include the following (as applicable for the battery type specified):
a.
Thermometer with specific-gravity correction scale.
b.
Hydrometer syringe.
c.
Set of socket wrenches and other tools required for battery maintenance.
d.
Wall-mounted, nonmetallic storage rack fitted to store above items.
e.
Set of cell numerals.
4.
Charger: Static-type silicon rectifier equipped with automatic regulation and
provision for manual and automatic adjustment of the charging rate. Unit shall
automatically maintain output voltage within 0.5 percent from no load to rated
charger output current, with ac input-voltage variation of plus or minus 10 percent
and input-frequency variation of plus or minus 3 Hz. Other features of charger shall
include the following:
a.
DC ammeter.
b.
DC Voltmeter: Maximum error of 5 percent at full-charge voltage; operated
by toggle switch to select between battery and charger voltages.
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c.
d.
e.
f.
g.
h.
2.10
A.
2.11
Ground Indication: Two appropriately labeled lights to indicate circuit
ground, connected in series between negative and positive terminals, with
midpoint junction connected to ground by normally open pushbutton
contact.
Capacity: Sufficient to supply steady load and float-charge battery.
Charging-Rate Switch: Manually operated switch provides for transferring to
higher charging rate. Charger shall operate automatically after switch
operation until manually reset.
AC power supply shall be 120 V, 60 Hz, provided by the purchaser. The
power supply voltage is subject to a+/- 10% variation in voltage and +/- 3
Hertz variation in frequency. After loss of ac power supply for any interval,
the charger shall automatically resume charging battery. Charger shall
regulate rate of charge to prevent damage due to overload and to prevent
fuses or molded case circuit breakers from opening unnecessarily.
Protective Feature: A current-limiting device or circuit shall be provided,
which limits output current to rating of charger but does not disconnect
charger from either battery or ac supply; to protect charger from damage
due to over-load, including short circuit on output terminals.
Electrical Filtering: Shall be provided to reduce charger audible noise to less
than 26 dB.]
CONTROL WIRING
Factory installed, complete with bundling, lacing and protection where necessary and complying
with the following:
1.
Flexible conductors of No. 14 AWG for wires across hinges, control and CT and VT
circuits and for interconnections between shipping units.
2.
Conductors sized according to NEC/NFPA 70, National Electrical Code for the duty
required.
ACCESSORIES
A.
Voltage indicator: Three (3) testing sockets suitable for verification of voltage presence.
B.
Operation tools: A set of operation tools shall be provided such as one operation handle for the
load interrupter switch, one operation handle for the grounding switch, touch-up paint and
grease packs.
2.12
A.
IDENTIFICATION
Storage for Manual: Include a rack or holder for the switchgear instruction manual and the
switchgear arrangement drawing.
PART 3 - EXECUTION
3.1
INSTALLATION
A.
3.2
General: Electrical contractor or switchgear installer to install switchgear in accordance with
manufacturer’s written instructions and the following specifications.
ADJUSTMENTS AND CLEANING
A.
3.3
Inspect interior and exterior of installed switchgear. Remove paint splatters and other spots, dirt
and debris. Touch up scratches and mars of finish to match original finish.
TESTING
A.
The switchgear furnished under this specification shall be fully tested and documented by
certified production test reports, in accordance with ANSI C37.20.3 and IEC 60420 (62271-105).
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B.
3.4
As a minimum, the following production tests shall be conducted for the medium voltage portion
of the switchgear, in accordance with IEC 60420 (62271-105):
1.
Power-frequency voltage (high-pot) test 1 min.
2.
Dielectric test of auxiliary circuit.
3.
Measurement of the resistance of the main circuit
4.
Partial discharge test
5.
Mechanical operation test
6.
Gas tightness test of gas-filled vessels
7.
Test of auxiliary devices
8.
Verification of the correct wiring
9.
Measurement of gas condition after filling.
WARRANTY
A.
3.5
Equipment manufacturer warrants that all goods supplied are free of non-conformities in
workmanship and materials for one year from date of initial operation, but not more than
eighteen months from date of shipment.
[DEMONSTRATION
A.
Switchgear Manufacturer shall provide a factory-authorized service representative for a
period of (1) day to train Owner's maintenance personnel in the following:
1.
In procedures and schedules related to startup and shutdown, troubleshooting,
servicing and preventive maintenance.
2.
Review data in the maintenance manuals.
3.
Schedule training with Owner with at least three weeks advance notice.]
END OF SECTION
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