MEDIUM VOLTAGE SWITCHGEAR & RAIN MAIN UNITS
PART I -GENERAL
1.01 RELATED DOCUMENTS:
A. Drawings and general provisions of Contract, including Conditions of
contract and Division-1 Specification sections, apply to section.
1.02 SUMMARY:
A. This section includes Medium Voltage Switchgear, Ring Main Units and
associated auxiliary equipment
B. Description of work: Medium Voltage Switchgear, Ring Main Unit (RMU)
installations comprise the following:
1. 12 kV vacuum circuit breakers for MVSG.
2. 12 kV SF6 load break switches for RMU.
3. 12 kV SF6 fused load break switches for RMU .
4. Power supply Control.
5. Equipment Supports.
6. Earthing of the RMU.
7. Earthing of the M.V.S.G.
8. Ancillary Work.
9. Connection to BMS system, including interface elements such as relays,
transducers, etc. as detailed in Division 15 Specification Sections BMS
schedules and/or shown on the Drawings.
10. Measurements Cell and devices.
C. Related Sections: include the following:
1. Division 16 Section "Basic Electrical Materials and Methods"
2. Division 16 Section "Earthing"
3. Division 16 Section "Medium-Voltage Cables" for cable terminations at
switchgear:
1.03 QUALITY ASSURANCE:
A. Acceptable manufactures: firms regularly engaged in the manufacturer of
primary switchgear of the types and capacities required, whose products
have been in satisfactory use in similar service for not less than 5 years as
approved by the engineer.
B. Standards Compliance : Comply with requirements of applicable local
codes, DIN/VED, IEC, BS, EN, NEC, NEMA, ANSI, and IEEE Standards,
pertaining to primary switchgear and ring main units.
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1.04 SUBMITTALS:
A. Product Data: submit full technical data of equipment for approval
including but not limited to the following:
1. Manufacturers catalogues, detailed description of construction provisions
for extension compliance with the standards, dimensions and weights,
operating characteristics, operating curves and error curves.
2. Details of miscellaneous items including pilot lights, cabling or wiring
incoming and outgoing feeder terminal supports, labels etc.
B. Shop and Construction Drawings: submit drawings for approval including,
but not limited to the following:
1- Plans and elevations with indication of M.V.S.G & R.M.Us mounted
components, dimensions and weights.
2- Arrangement of equipment and general layouts.
3- One-line diagram of power system showing current ratings of M.V.S.G &
R.M.U, busbars and types and locations of protective gear (relays,
metering instruments, CTs, VTs) etc.
4- Schematic and elementary diagrams of control circuits.
5- Foundation details, grouting holes, installation details.
6- Physical arrangement of incoming and outgoing feeders, instrument
transformers, busbars connections etc.
7- Dimensions and weights of control power supply and other auxiliary
equipemtn or components.
C. Technical Literature: submit the following for approval prior to equipment
manufacture.
1- Schedule of selected circuit breaker, load break switch, relays and control
gear, with complete identification of each component and its
characteristics.
2- Protection coordination scheme, including pick-up settings and
time-grading, together with time-current curves and range of adjustments
etc. as required to coordinate with upstream and downstream. Protective
devices of the complete system
D. Type Test certificates: submit to verify compliance of main equipment with
the relevant IEC standards including the following:
1. Impulse withstand-voltage tests.
2. Power frequency withstand ¡Vvoltage tests.
3. Temperature ¡Vrise tests.
4. Sort time current tests.
5. Verification of making and breaking capacity.
6. Mechanical endurance/operation tests.
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7. Verification of degrees of protection for persons against contact with
live and moving parts.
8. Internal arc tests.
9. Protection degree test to IEC 60529.
E. Routine Tests: Each complete R.M.U & M.V.S.G is to undergo routine tests
at the manufacturer's works in accordance with the relevant standards.
Submit routing test reports, prior to shipping equipment, indicating ambient
test conditions and guaranteed rating of equipment under site conditions.
F. Qualification Data: For firms and persons specified in "Quality Assurance"
Article.
G. Field test reports: indicate and interpret test results for compliance with
performance requirements.
H. Complete operations and maintenance manuals/charts including spare parts
data and wiring diagrams of all equipment furnished under this section.
I. Before engineer's approval and prior to fabrication, submit foregoing
including M.V.S.G & R.M.U shop drawings to Utility Co. for approvals.
1.05 WARRANTY
Manufacturers warranty: Submit a warranty signed by the manufacturer
agreeing to repair, restore or replace any defective equipment specified in this
section during the specified warranty period.
- Warranty period: 1 year from date of Substantial Completion.
1.06 DELIVERY, STORAGE, AND HANDLING:
A. Deliver in shipping splits of lengths that can be moved past obstructions in
delivery path as indicated.
B. Store so condensation will not form on or in switchgear.
C. Apply temporary heat where required to obtain suitable service conditions.
D. Handle M.V.S.G & R.M.U using factory-installed lifting provisions.
1.07 COORDINATION:
A. Coordinate layout and installation of M.V.S.G & R.M.U with other
construction and room dimensions. Advise the Engineer in case of conflict.
B. Coordinate size and location of concrete or mounting bases. Concrete
reinforcement, and formwork requirements are specified in Division 3
section "Cast-in-place concrete."
1.08 SPARE PARTS AND TOOLS:
A. Spare Parts:. Provide spare parts, as recommended by the manufacturer, for
one year maintenance as expected under local conditions, and to allow for
emergency replacement due to accidental breakage or failure. Spare parts are
to include, but are not limited to, the following:
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1. Two sets of each type of lamp, fuse, auxiliary switch, trip coil, control
switch, selector switch, selector switch, neon indicator and the like.
B. Tools and instruments: Provide tools and instruments required for normal
routing inspection, testing, operation and maintenance including levering
crank, manual charging handle, manual shutter operator, testing jumpers and
HV test bushings, set of rail extensions, digital micro ohm-meter, set of
mobile lifting and handling equipment etc. as necessary for the type of
M.V.S.G & R.M.U.
PART 2 ¡VPRODUCTS
2.01 MANUFACTURERS:
A. Available Manufacturers: subject to compliance with requirements, provide
products by one of the following or approved equal:
1. ABB (Sweden/German/Egypt)
2. Merline-Gerin (France/Egypt)
Warranty: Provide a one year warranty for all equipment specified in this
section.
2.02 RING MAIN UNITS:
3. Each ring main unit comprises No.3 three-pole SF6 load break switches
rated 630 Amps for the incoming and outgoing ring main feeders cables,
one three-pole SF6 fused load break switch 630A for the outgoing cable
connected to the M.V.S.G as shown on the drawings. The unit must
comprise measuring compartment including three current transformers and
voltage transformers protected with H.R.C fuses to effect metering the
input electric power by the electricity authority. The three pole load break
switch with fuse shall be provided with tripling coil which shall be activated
by buchloz relay installed on the transformer.
A. Cable termination boxes shall be provided for the incoming and outgoing,
also for the 12 KV switchboard supply feeder.
B. Switch disconnectors shall be manufactured to IEC 298, 294 and 262
category B VDE-67 part 3 and 6 or BS 5227 or any approved equal.
C. They shall be SF6 gas insulated compact ring main unit of IP42 capable of
interrupting safely, their nominal full load current.
D. Busbars: Air-insulated, high conductivity, electrolytic tin plated copper,
modular, designed to withstand worst short-circuit conditions without
allowing permissible temperature rise at ambient conditions to be exceeded,
in accordance with the standards. Busbar connection from one unit of
witchgear to another is to be expansion/contraction compensated, plated
and bolted. Busbar supports are to be flame-retardant, track-resistant, glass
polyester, porcelain or equally reliable fiberglass reinforced epoxy to
approved standards.
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E. Busbars: Additional epoxy insulation is to be provided to busbars applied
by the fluid-dip process. Busbar connections are to be insulated with easily
installed, performed vinyl boots, secured by nylon hardware.
F. Earth Bus: Copper of not less than minimum size required by the Standards,
designed to withstand worst earth-fault current of power system without
showing any signs of thermal or mechanical damage or degradation. Earth
bus is to extend full length of switchgear.
G. Power Cable Terminations: Fixed bolted type, unless otherwise specified,
complete with standard fittings and accessories for connection of incoming
and outgoing cables. Cable compartment is to be designed to permit cables
to enter enclosure and connect at respective terminals from below, or as
shown on the Drawings. Terminations are to include appropriate sealing
ends, fittings and accessories for type of cable, including stress cones or
other stress relieving accessories, heat shrinkable sleeving, end boxes or
end bushings and fittings of any kind necessary to support and protect
specified cable ends.
H. Earthing facilities are to be provided for earthing and/or short-circuiting the
feeder at its terminals through built-in, safety-interlocked, quick-make
earthing switch, without use of loose attachments.
I. Metal cases of instruments and control devices are to be connected by bare
copper conductors of not less than 2.5mm2 cross-section to nearest earth
bar.
J. Test terminal blocks are to be provided inside insulating covered bases for
instruments, instrument transformers, relays etc. in LV compartments.
K. Components are to be interchangeable when of same rating and function.
L. Finish: Inner and outer surfaces of steel enclosures and structure are to be
cleaned, phosphatized primed with rust inhibiting primer and finished with
two coats of baked enamel, color standard gray (RAL 7033) unless
otherwise approved. Finish is to be vermin and fungus proof and suitable
for worst climatic conditions on site.
M. The switch disconnector shall have the following Ratings:
1. Rated Voltage : 12 kV
2. Nominal Service Voltage : 11 kV
3. Rated Frequency : 50 Hz.
4. Rated One Minute Power Frequency Withstand Voltage (rms) to earth
and between phases : 28 kV
5. Rated Impulse Withstand ¡VVoltage (1.2/50 micro-sec) (peak): 75kV
6. Rated Normal Current of Busbars: (630 A ) as shown on the Drawings.
7. Rated short time withstand-current: 20 kV for 1 second.
8. Rated peak withstand-current : 50 kA
9. Load breaking capacity : 30A at power factor 0.7 and Un
10. Closed loop breaking capacity: 30A at power factor 0.3 and 0.25Un
11. Rated short time current for 1 second:
a. Line blades 50 KA rms.
b. Earth blades 25 KA rms.
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12. Peak withstand current
a. Line blades 75 KA rms.
b. Earth blades 50 KA rms.
N. The load break switches shall be operated by hand-operated handles
through levers. A protective barriers must be provided to safeguard the
personnel from unintentional contact with the live parts during switching
operations.
Marking labels shall be fitted to indicate the ON/OFF positions of the
switches and the hand-operated handles shall be provided with locks.
Insulating barriers shall be inserted between the open contacts when
working on cables.
O. Earthing switches are to be provided on the feeders side to enable earthing
the cable feeders when working on the cables.
P. Mechanical interlocking between the load break switches and their relevant
earth switches such that no load break switch can be switched on as long as
his mate earth switch is in the ON position and vice versa.
4. Each Ring main unit must be equipped with earth fault indicators of the
type and according to the electricity authority requirements.
Q. Enclosure shall be made of steel sheet 2.5 mm thick before paint and treated
against rust and provided with priming, intermediate and finishing coats of
electrostatic painting powder from inside and outside the external coat is
generally light gray colour.
R. The outgoing circuit breakers shall be able to be controlled via the B.M.S
system
2.03 MEDIUM VOLTAGE SWITCHGEAR:
A. The medium voltage switchgear shall be dead front, self-supporting
structure, consists of line-ups of metal enclosed, air-insulated and
compartmented cubicles. VACCUM type circuit breakers on draw-out
trucks as indicated. The truck is fully interlocked with the interrupter and
the stationary cubicle. It is manually moved horizontally from the "
Operating " to the " Isolated/Test" position without the use of auxiliary
equipment. A fully isolated low-voltage compartment is integrated.
The switchgear cubicles and interrupters shall be factory assembled and
type-tested. All switchgear components should be provided according to
electricity authority requirements.
B. The stationary part of the cubicles are built as a self-supporting structure,
bolted together from rolled steel sheets of at least 2.5mm gauge, rated for
12KV. Each cubical is to be divided into three sealed and isolated
compartments by arc and pressure resistant fiberglass reinforced epoxy
partitions, i.e, the busbar, cable connection and circuit breaker
compartment. The vertical partitions shall carry automatic,
phase-segregated safety-shutters made of insulating material.
These shutters are to seal in both directions, effectively preventing ionized
gases from fault-arcs to spread to the neighboring compartment. Each
compartment shall have its own pressure relief device.
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C. The interrupter truck shall carry SF6 circuit breaker, with associated
operating mechanism and auxiliary devices. By manually moving the truck
it may be brought into a distinct operating and isolating test position. The
front shield of the truck shall engage firmly with the frame of the cubicle
when locked in the operating position, and become an arc and
pressure-proof part of the enclosure.
D. All protective relays, monitoring and control devices of a feeder shall be
accommodated in a metal-enclosed LV compartment on top of the HV
enclosure. Device mounting plates, cabling troughs, and the central LV
terminal strip(s) shall be located behind a separate lockable door fitted with
a Plexiglas window. Transformer feeder circuit breaker relays shall be fully
coordinated with transformer starting currents of 400¡Ómilliseconds.
E. The busbars shall be rectangular, drawn from pure copper with cross
section area 1200mm2 and shall be mounted on ribbed, cast-resin post
insulators sized to take up the dynamic forces resulting from short-circuits.
The busbar shall have the following specification:
- Rated voltage 24KV
- Nominal operating voltage 22KV
- Thermal withstand short circuit current for 1 second 50 KV
F. Line and load side primary disconnects shall have flat, spring-loaded and
silver plated semispheric pressure contacts for low contact resistance and
good ventilation.
G. Additional Safety Features
A series of sturdy mechanical interlocks shall force the operator into the
only safe operating sequence of the switchgear, preventing positively the
following:
ƒx Moving the truck with the circuit-breaker closed.
ƒx Switching the circuit-breaker in any but the locked "operating" or
"Disconnected/Test" position.
ƒx Moving the truck into the operating position with the low voltage plug
disengaged.
ƒx Engaging the grounding switch with the truck in the "Operating" position,
and moving the truck into this position with the grounding switch engaged.
H. In the "Connected" and the "Disconnected/Test" position of the truck, the
switchgear shall be totally protected against contact with live parts with
objects larger than 1 mm in diameter.
I. The entire switchgear and circuit breakers shall be rated to operate
continuously under full capacity in 45OC ambient temperature conditions.
J. The switchgear parts shall comply with the relevant I.E.C standards
specification regarding design, workmanship and testing.
1. HV metal enclosed or metal clad switchgear I.E.C.298
2. Common clauses for HV switchgear I.E.C 694
3. Circuit ¡V breakers I.E. C 56
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4. Metering and protective C.T.'s I.E.C. 185
5. Metering and protective V.T.'s I.E.C. 186
6. Relays I.E.C. 255
7. Reading instruments
(ammeters, voltmeters). I.E.C. 51
8. Watt-hour meters I.E.C 521
K. Precaution shall be taken at contacts between aluminum and other material
to avoid electrolytic action.
L. All circuit-breakers on the 12 KV switchgear shall be interchangeable.
Each incoming, outgoing feeder and bus-tie cubicle shall comprise circuit
breakers. The circuit breakers shall be VACUUM type, mounted on
withdrawable trucks, and shall fulfill the following technical specifications:
Type VACUUM
Rated voltage KV 12
Nominal operating voltage KV 11
Rated current:
- Incoming feeders Amps 630
- Bus-tie Amps 630
- Outgoing feeders Amps 630
- Rated breaking current r.m.s. at rated voltage
for 3 second KA 50
- Making current, peak value KA 75
- Dynamic withstand current, peak value KA 75
- Rated operating sequence O-0.3s-CO-3min-CO.
One minute power frequency withstand voltage:
- Phase to earth KV 75
- Phase to phase KV 75
- Through open contacts KV 100
Impulse withstand voltage (1.2/50 £g.s peak):
- Phase to earth KV 125
- Phase to phase KV 125
- Through open contacts KV 145
The circuit breaker is equipped with closing spring charged by an electric
motor operated by 110V AC.
It shall have two electric coils one for tripping and the other for closing.
Circuit breaker opening and closing can be done electrically by push button
at low voltage compartment and mechanically at the circuit breaker.
For ac control, a capacitor trip device is used with each circuit breaker shunt
trip to ensure that energy will be available for tripping during fault
conditions. A control power transformers is required on the sourceside of
each incoming line breaker. Closing bus tie or bus sectionalizing breakers
will require automatic transfer of control power. This control power
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transformer may also supply other ac auxiliary power requirements for the
switchgear.
Operating spring can be manually charged too. It shall be equipped with a
counter to count the number of operations and an indication of this spring
status.
M. The switchgear shall be constructed so that it corresponds to the degree of
protection IP65 according to IEC publication No. 529.
N. Each cubicle must equipped with space heaters to prevent moisture &
humidity ingress (220Vx2x200W) one in cable compartment and the other
in circuit breaker compartment controlled by miniature breaker and by
hygrostat.
O. All circuit breaker shall equipped with the following:
a. Gas pressure gauge,
b. In case of insufficient gas pressure than the limit assigned by the
manufacturer for proper operation the circuit breaker should be lockout
(blocked).
c. Valve for gas filling and drainage.
P. Switchgear shall consists of the following panels:
1. Two (2) incoming feeder panels.
2. Two (2) outgoing feeder panels.
3. One (1) panel sectionalize.
4. One (1) panel adapter.
Q. The switchgear shall be of the totally enclosed indoor type, of size, rating
and arrangement as shown on drawings and indicated in the specification.
The complete assembly shall be floor mounted, free standing, with
matching cases, to form a continuous integral structure. The housing shall
consist of folded sheet steel sections welded together and shall be of robust
construction. Switchgear shall have front and rear access.
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R. Direct panel to panel busbar connection shall be made without the use of
interconnecting links.
The arrangement shall permit cables to enter from the bottom of the
enclosure and connect at their respective terminals without interference.
S. Cable termination boxes shall be provided for incoming and outgoing
feeders having 1-core, armored XLPE insulated, Copper cables of 300 sq.
mm. cross sectional area for outgoing feeders and 1-core, armored XLPE
insulated, copper cables of 300 Sq. mm cross sectional area for incoming
feeders.
T. Facilities shall be provided for earthing the feeder side of the circuit breaker
without the use of loose attachments.
U. Finish shall be battle ¡Vship gray, "or any other colour approved by
Engineer", vermin-proof and suitable for the climatic conditions of the site.
V. Each switchgear unit shall be provided with a metal rating and name plate
giving the required particulars in accordance with the IEC
recommendations.
W. Instruments and meters shall be of the flush pattern with phenolic-black
finish digital type.
Relays shall be of the flush fixed pattern digital type.
Test terminal blocks shall be provided for all instruments, relays ¡Ketc.
X. Incoming Feeder Panels:
Shall be equipped with the following components:
ƒx One withdrawable, motor operated, SF-6 type circuit breaker rated 630 A,
with 50 KA short circuit breaking capacity.
ƒx One set for busbars rated 800 A and designed to withstand
electrodynamics forces under worst short circuit conditions of 50 KA.
ƒx Three current transformers each with separate secondaries for metering
and protection.
Accuracy class : 0.5 M5 for metering
5P 10 for protection
Ratio : 300-600/5/5A
ƒx Indicator lamps.
ƒx Three ammeters with scale 0-300-600 A and accuracy class 2.
ƒx One voltmeter scale 0-12 KV class of accuracy class 2 with selector
switch.
ƒx K.V.A.R ¡V meter, for three phase, 3 wire unbalanced loads, class 3 rating
110V/5A to operate from the secondaries of voltage and current
transformers.
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ƒx Ditto but KW ¡Vmeter, but with class 1 and with maximum demand
indicator.
ƒx Power factor meter.
ƒx Two push buttons on and off.
ƒx One three phase non-directional over current relay with definite time delay
characteristic:
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.5-3.5) In
d. Current steps 0.1 In (up to 2 In)
e. Time setting range (0.1-3) sec
f. Time steps 0.1 sec
g. The relay must has a flag or LED on its face to indicate relay
operation.
h. High set over current (short circuit) element:
1. current setting range 2-10 In/¡Û
2. Time setting range (0.04-2) Second.
3. Time steps 0.05 up to first 0.3 secon
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i. Output contacts 2 normally open contacts at
least each 5A rating
ƒx Non-directional earth fault relay definite time characteristic.
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.1-0.5) In
d. Current steps .0.1 In
e. Time setting range (0.1-3) sec
f. Time steps .0.1 sec
g. Output contacts 2 normally open contact at least
each 5A rating
h. The relay must has a flag or LED on its face to indicate relay
operation.
ƒx Three phase directional over current relay:
For phase-phase faults with the following specifications.
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.2-1) In
d. Current steps 0.1 In
e. Time setting range (0.05-3) sec
f. Relay internal angle 30O ¡Û60 O
g. Output contacts 2 normally open contacts each
5A rating
h. The relay must has a flag or LED on its face to indicate relay
operation.
ƒx Directional earth fault:
For phase-to earth faults with the following specifications.
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.1-0.4) In
d. Time setting range (0.05-3) sec
e. Time steps (0.05) sec
f. Relay internal angle 0-90 O with steps not more than 15 O
g. Output contacts 2 normally open contacts each
5A rating
h. The relay must has a flag or LED on its face to indicate relay
operation.
ƒx Three under voltage relays adjustable between 30-80% of rated value.
(time delayed).
Relay characteristic must be coordinated with and approved by the Electric
Power Authority
ƒx Earthing switch
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Y. Outgoing Feeder Panel.
Shall be equipped with the following components:
ƒx One withdrawable, motor operated, VACUUM type circuit breaker rated
630A, with 50 KA short circuit breaking capacity.
ƒx One set of insulated busbars rated 1200 Amps and designed to withstand
electrodynamics forces under worst short circuit conditions of 25 KA.
ƒx Three current transformers with separate secondaries for metering and
protection
Accuracy class : 0.5 M5 for metering
5P10 for protection
Ratio : 200-400/5/5 A
ƒx Indicator lamps
ƒx Three ammeters with scale 0-200-400A and accuracy class 2.
ƒx One three phase none directional over current relay, same specifications as
that for incoming feeder.
ƒx Non directional earth fault relay, same specifications as that for incoming
feeder.
ƒx Earthing switch.
Z. Bus Sectionalize Panel:
Shall be equipped with the following components:
ƒx One withdrawable, motor operated, SF-6 type circuit breaker rated 630A,
with 50 KA short circuit breaking capacity.
ƒx One set of insulated busbars rated 1200 A, and designed to withstand
electrodynamics forces under worst short circuit conditions of 50 KA.
ƒx Three ammeters with scale 0-600 A and accuracy class 2.
ƒx Three current transformers for protection:
Ratio : 600-1200/5/5 A
Accuracy class : 0.5 M5 for metering
5P10 for protection
ƒx One three phase none directional over current relay, same specifications as
that for outgoing feeder.
ƒx Electrical interlock between the incoming & bus coupler circuit breakers
shall be provided as follows:
a. Bus tie circuit breaker is normally switched off while the incoming
feeders circuit breakers are switched on.
b. If the incoming feeders circuit breaker in any section are switched off,
then the bus tie circuit breaker can be switched on.
c. If one of incoming feeders circuit breakers in any one or in the two
sections is switched off the bus tie circuit breaker can be switched on.
d. Mechanical interlocks prevent the following faulty operations:
- Insertion or withdrawal of a closed CB.
- Closing of breaker not locked in service or test position.
- Closing of earthing switch with breaker in service position.
- Breaker insertion with earthing switch closed.
- Breaker insertion with LV plug not connected.
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ƒx Circuit breaker mechanism shall have an anti pumping relay.
ƒx Enclosure heater.
AA. Tests:
1. Supply test results to confirm that the switch has been tested to
substantiate designs according to applicable standards verifying not only
the performance of the switch and integrated switch-fuse assembly, but
also the suitability of the enclosure venting, rigidity and bus bracing. In
addition, factory test each switch in accordance with approved
standards.
2. All tests shall be carried out by the manufacturer at works and at his
expense and under control and supervision of electricity Distribution
Company.
BB. Equipment Data
Equipment data for materials covered under this section shall include but
not be limited to the following:-
Construction and installation details for the main 12 KV switchgear
equipment.
Floor plan and top view showing outline dimensions and arrangement of
cubicles.
Details of connection of high voltage cables to the cubicles.
Wiring and schematic diagrams of power, control, relay, metering and
similar circuits. The separate schematic diagrams shall include complete
three line diagrams of all instruments, switches, any other devices in the
12KV switchgear Handling, installation and assembly drawings.
Key interlocking scheme showing key numbers and operations performed
The equipment data to be provided prior to ordering any material covered
by this section shall include but not be limited to the following:
Complete technical data on the 12KV switchgear other equipment
including data on operating characteristics, compliance with standards,
dimensions and sights, detailed description operating mechanism etc.
CC. M.V to be provided with special key lock and accordingly master key shall
be valid for all panels at plant.
DD. Color of M.V panel (RAL 7032).
Complete technical data on instruments protective and auxiliary relays,
measuring instruments including manufacturer's atalogues operating
characteristics, operating curves, detailed description etc.
EE. DC batteries system and all electricity authority requirements.
FF. All bus bars shall be electrical copper of section not less than 400 mm2,
mounted on support insulators enough to withstand mechanical forces,
which may happen due to short circuit 50kA r.m.s. at 12kV for l sec.
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GG. Each switch compartment shall be equipped with suitable clamp or any
other mean for supporting and fixing the cable or end box.
HH. All wiring shall be in PVC conduits..
II. Automatic reset type complete with ferranti current transformer, which will
be erected around the cable sheath, according to the specification and Shall
be mounted inside a metal or fiber-glass box with an opening to show the
indicator flag.
JJ. Control and monitoring of each unit is to be provided on front panel and is
to include mimic diagram, operating handles of main device and earthing
switches, position indicators, potential indicators, identification and
instruction plates, protective devices, metering and indicating instruments,
key and padlockable devices, as specified and shown on the drawings.
KK. Access to LV wiring is to be from front of cubicle for control, protection,
test terminal blocks and associated LV power connections. Multi-pin,
disconnectable, lock-in type plug and socket arrangement is to be provided
between circuit breaker and stationary part of cubicle.
LL. Anti-condensation heaters with thermostat, switch and pilot lamp and of
rating recommended by manufacturer are to be provided in each section of
switchgear assembly.
MM. Wiring diagram, suitably protected and located inside LV compartment
of each unit, is to indicate all data and components related to the particular
unit and its external circuitry.
NN. Insulating Mat: Anti-slip, synthetic, insulating, rubber mat, minimum
5mm thick and 900mm wide, with heavy canvas lining on lower face, is to
be provided for full length in front of switchgear assembly.
OO. Accessories are to include the following:
1. 2 N.O and 2 N.C; auxiliary contacts on each switch.
2. Automatic reset earth fault indicator operated by core-balance type CT
located near and outside cable terminals and visible from front.
3. Insulating rubber gloves, earthing equipment, fuse tongs, schematic
diagram with equivalent ratings and references, operating handle etc.
placed inside compartment.
4. Shunt trip relay on fuse switch combination, operated by push buttons or
relay, using auxiliary power.
5. Under-voltage relay, operated by auxiliary power electrical closing
devices, geared motor connected to switch spring charging mechanism,
with closing release, operated from auxiliary power supply.
6. MV fuses: High-breaking capacity, totally enclosed, cartridge type fuselinks,
current limiting, with striker pins to cause switch to open. Fuses
are to comprise fuse links and fuse bases insulated to respective
standards.
16
2.04 MV CIRCUIT BREAKERS:
A. Type: VACUUM circuit breaker using rotating are or puffer principle, with
closed gas circuit, and with pressure detector to prevent operation of circuit
breaker in case of loss of gas pressure within the sealed enclosure. Sealed
enclosure is to be stainless steel.
B. VACUUM breakers, are to be provided with gas filling valve and with
pressure switches, one per pole to initiate alarm in case the pressure of the
VACUUM gas drops below manufacturer set values. Alarm serine is to
provided to initiate alarm.
C. Operating Mechanism: Mechanically and electrically trip-free, stored
energy, spring loaded, manually charged by lever or hand-crank,
electrically charged by suitably rated universal motor, and capable of one
complete off-on-off cycle in case of loss of control power. Circuit breaker is
to have electrical close solenoid and two trip coils, mechanical on and off
push buttons, mechanical on/off/charged indicators, operation counter and
auxiliary switches to satisfy all functions specified or shown on the
Drawings. Five N.C. and five N.O spare auxiliary switches for future use
are to provided in addition to those required. Insertion of manual spring
charging lever or hand-crank is to automatically disconnect the motor. Slow
closing of circuit breaker contacts for inspection and adjustment is to be
possible whilst in the disconnected position.
D. Automatic tripping is to be by indirect auxiliary power through CT operated
protective relays.
E. Interchangeability: Circuit breakers of different current ratings are not to be
interchangeable. Circuit breakers of same current rating are to be wired
alike and interchangeable.
2.05 INSTRUMENT TRANSFORMERS AND CONTROL SWITCHES:
Instrument transformers shall be sized for burden requirements of connected
meters with accuracy class as follows:
CURRENT TRANSFORMERS (CT's):
Class 0.5 for metering and 1.0 for protection n.10
POTENTIAL TRANSFORMERS Metering - Class 1.
All potential transformers shall be provided with current limiting fuses. Voltage
rating for the secondary winding shall be of ratios:
12000 / 110 / 110 /
¡Ô 3 ¡Ô 3 3
For metering and protection the thermal rating of the transformers shall be
sufficient to provide the total current required to operate the burdens on the
secondaries without exceeding the rating of transformer as indicate on nameplate.
PT's (1 per phase) shall be installed either as a unit drawout assembly or with an
isolating switch in a separate compartment to that the transformers, primary fuses
and secondary circuits may be inspected and tested in a completely de-energized
condition. CTS shall have mechanical and thermal rating equal to the rating of the
circuit breaker and LBS. secondary rating shall be 5 amperes and primary ratings
17
shall be as shown on one-line diagram. Transformer shall be capable of carrying
120 percent of rated current for one hour. Ground current sensing transformers
shall have a one-ampere secondary current.
Control switches shall be the rotary enclosed type with positive means for
maintaining contact position.
2.06 ACCESSORIES
A. Signage:.Each R.M.U and M.V.S.G shall have engraved laminated
nameplates screwed to the doors of each individual compartment and
wiring diagrams pasted inside each door.
Each M.V.S.G & R.M.Us shall be furnished with a sign marked
"DANGER ¡V HIGH VOLTSGE" Letters shall not be less than 25mm
high, 6mm stroke. Signs shall be laminated plastic, red letters with a white
background.
All compartments with voltages from sources outside of the compartment
shall have a sign on the compartment door marked "CAUTION ¡V THIS
UNIT CONTABINS A VOLTAGE FROM A SOURCE OUTSIDE OF
THIS UNIT". Letters shall be black on a high visibility yellow
background. Signs shall be adhesive backed vinyl approximately 75mm
by 125mm.
All nameplates and signage shall be printed in both English and Arabic.
PART 3- EXECUTION
3.01 INSTALLATION:
A. Locations and Layout: Exact locations and physical layout of equipment and
components may be varied as required to suit manufacture's design and as
approved, provided the required functions and operations are accomplished,
follow the identification of the units indicated on drawings exactly to ease
checking and building maintenance procedures.
B. Equipment Bases: Ensure that concrete bases and foundations provided for
installation of equipment are constructed in accordance with approved shop
and construction drawings and equipment manufacturer's drawings and that
holes for fixing bolts and provisions for passage of cables etc. are provided as
required.
C. Cable Trenches: Ensure that trench construction and covers provided for
installation of power and control cables are in accordance with approved shop
and construction drawings.
[
D. Built ¡VIn Items: Ensure that equipment supports, fixings and the like, and
sleeves for passage of feeders and cables which are to be built into concrete
foundations, bases, cable trenches or building structure are provided as and
when required and that they are properly installed.
E. Equipment: Install on concrete bases etc. and assemble completely plumb and
level, before grouting in holding-down bolts.
F. Supports and Terminations: Install all incoming and outgoing cable supports,
cable ends and termination fittings required for MV, LV and control cables
18
G. Relays: Set in accordance with manufacturer's instructions and the local
power authority requirements.
H. Earthing: ensure that earthing installation is as described in Division 16
Section "Earthing" of the Specification and/or as shown on the Drawings.
I. Temporary Lifting provisions: Remove temporary lifting eyes, channels
brackets and temporary blocking of moving parts from switchgear units and
components.
3.02 IDENTIFICATION.
A. Identify field-installed wiring and components and provide warning signs as
specified in Division 16 Section "Basic Electrical Materials and Methods.
B. Diagram and Instructions: Frame under clear acrylic plastic on the front of the
M.V.S.G & R.M.Us.
1. Operating Instructions: Printed basic instructions for R.M.U & M.V.S.G.
2. Storage for Manual: Include a rack or holder, near the operating
instructions, for a copy of the maintenance manual.
3. System Power Riser Diagrams: Depict power sources, feeders
distribution components and major loads.
3.03 CONNECTIONS:
A. Tighten bus joint, connector and terminal bolts according to manufacturer's
published torque-tightening values. If manufacturer's torque values are not
indicated, use those specified in applicable Standards.
3.04 FIELD QUALITY CONTROL:
A. Equipment: Inspect equipment upon delivery to site and report any damage
to the Engineer.
B. Switchgear: Inspect and check switchgear for completeness and as
recommended by the manufacture and check phasing of buses, contact
alignment and clearances.
C. Components: Check component ratings, types, sizes and wiring connections
including current and voltage transformers, fuses, switches instruments and
relays.
D. Before energization carry out at least the following tests:
1. Insulation resistance on busbars (with circuit breakers in disconnected
position) circuit breakers bushings and insulators feeder terminals etc.,
using at least a 5 kV megger for MV circuits and a 1000 V megger on all
control and protection circuit with relays lamps and the like components
disconnected, to ensure satisfactory insulation resistance as
recommended by the Standards and approval practices.
2. High voltage tests on busbars circuit breakers in disconnected position
switches, VTs and insulators by applying HV a.c test voltage between
phases and phase to earth at 80% of the IEC voltage withstand test for
1-minute.
19
3. Resistance across closed contacts of circuit breakers using appropriate
micro-ohm meter.
4. Polarity check and ratio tests for CTs.
5. Calibration checks and adjustment for ammeters and voltmeters.
6. Primary and/or secondary injection tests to check relay operation suing
appropriate test sets, followed by tripping of circuit-breaker once only,
through its protective relay circuit.
E. Cables: with circuit breaker in disconnected position, ensure that HV testing
of feeder cable and respective termination is carried out as required under
cable tests.
F. After energization a carry out inspection and checking as follows:
1. Breakers are to be closed one at a time with as little load on the feeder as
possible, check meters as load is increased and any indication of
overheating detected by appropriate instruments or sensors.
2. Open and withdraw circuit breaker after a prolonged test run, inspect and
check circuit breaker conditions isolating contacts, contacts on all
instruments and control switches, connections at terminal blocks etc.
busbar connections and busbar for any indication of overheating check for
loose connections and bolts etc. and finally re-apply megger tests to ensure
same quality of insulation as before energization.
3. Close circuit breaker slowly, while in the disconnected position and
inspect contacts and/or contact movement and compare with design
figures.
G. Manufacturer's instructions are to be followed under all circumstances.
Carry out and record measurement and tests recommended by the
manufacturer.
3.05 CLEANING:
A. Inspect interior and exterior of installed switchgear. Remove paint-splatters
and other sports, dirt, and debris. Touch up scratches and mars of finish to
match original finish.
B. Vacuum ¡V clean all interior equipment.
END OF SECTION 16343
PART I -GENERAL
1.01 RELATED DOCUMENTS:
A. Drawings and general provisions of Contract, including Conditions of
contract and Division-1 Specification sections, apply to section.
1.02 SUMMARY:
A. This section includes Medium Voltage Switchgear, Ring Main Units and
associated auxiliary equipment
B. Description of work: Medium Voltage Switchgear, Ring Main Unit (RMU)
installations comprise the following:
1. 12 kV vacuum circuit breakers for MVSG.
2. 12 kV SF6 load break switches for RMU.
3. 12 kV SF6 fused load break switches for RMU .
4. Power supply Control.
5. Equipment Supports.
6. Earthing of the RMU.
7. Earthing of the M.V.S.G.
8. Ancillary Work.
9. Connection to BMS system, including interface elements such as relays,
transducers, etc. as detailed in Division 15 Specification Sections BMS
schedules and/or shown on the Drawings.
10. Measurements Cell and devices.
C. Related Sections: include the following:
1. Division 16 Section "Basic Electrical Materials and Methods"
2. Division 16 Section "Earthing"
3. Division 16 Section "Medium-Voltage Cables" for cable terminations at
switchgear:
1.03 QUALITY ASSURANCE:
A. Acceptable manufactures: firms regularly engaged in the manufacturer of
primary switchgear of the types and capacities required, whose products
have been in satisfactory use in similar service for not less than 5 years as
approved by the engineer.
B. Standards Compliance : Comply with requirements of applicable local
codes, DIN/VED, IEC, BS, EN, NEC, NEMA, ANSI, and IEEE Standards,
pertaining to primary switchgear and ring main units.
2
1.04 SUBMITTALS:
A. Product Data: submit full technical data of equipment for approval
including but not limited to the following:
1. Manufacturers catalogues, detailed description of construction provisions
for extension compliance with the standards, dimensions and weights,
operating characteristics, operating curves and error curves.
2. Details of miscellaneous items including pilot lights, cabling or wiring
incoming and outgoing feeder terminal supports, labels etc.
B. Shop and Construction Drawings: submit drawings for approval including,
but not limited to the following:
1- Plans and elevations with indication of M.V.S.G & R.M.Us mounted
components, dimensions and weights.
2- Arrangement of equipment and general layouts.
3- One-line diagram of power system showing current ratings of M.V.S.G &
R.M.U, busbars and types and locations of protective gear (relays,
metering instruments, CTs, VTs) etc.
4- Schematic and elementary diagrams of control circuits.
5- Foundation details, grouting holes, installation details.
6- Physical arrangement of incoming and outgoing feeders, instrument
transformers, busbars connections etc.
7- Dimensions and weights of control power supply and other auxiliary
equipemtn or components.
C. Technical Literature: submit the following for approval prior to equipment
manufacture.
1- Schedule of selected circuit breaker, load break switch, relays and control
gear, with complete identification of each component and its
characteristics.
2- Protection coordination scheme, including pick-up settings and
time-grading, together with time-current curves and range of adjustments
etc. as required to coordinate with upstream and downstream. Protective
devices of the complete system
D. Type Test certificates: submit to verify compliance of main equipment with
the relevant IEC standards including the following:
1. Impulse withstand-voltage tests.
2. Power frequency withstand ¡Vvoltage tests.
3. Temperature ¡Vrise tests.
4. Sort time current tests.
5. Verification of making and breaking capacity.
6. Mechanical endurance/operation tests.
3
7. Verification of degrees of protection for persons against contact with
live and moving parts.
8. Internal arc tests.
9. Protection degree test to IEC 60529.
E. Routine Tests: Each complete R.M.U & M.V.S.G is to undergo routine tests
at the manufacturer's works in accordance with the relevant standards.
Submit routing test reports, prior to shipping equipment, indicating ambient
test conditions and guaranteed rating of equipment under site conditions.
F. Qualification Data: For firms and persons specified in "Quality Assurance"
Article.
G. Field test reports: indicate and interpret test results for compliance with
performance requirements.
H. Complete operations and maintenance manuals/charts including spare parts
data and wiring diagrams of all equipment furnished under this section.
I. Before engineer's approval and prior to fabrication, submit foregoing
including M.V.S.G & R.M.U shop drawings to Utility Co. for approvals.
1.05 WARRANTY
Manufacturers warranty: Submit a warranty signed by the manufacturer
agreeing to repair, restore or replace any defective equipment specified in this
section during the specified warranty period.
- Warranty period: 1 year from date of Substantial Completion.
1.06 DELIVERY, STORAGE, AND HANDLING:
A. Deliver in shipping splits of lengths that can be moved past obstructions in
delivery path as indicated.
B. Store so condensation will not form on or in switchgear.
C. Apply temporary heat where required to obtain suitable service conditions.
D. Handle M.V.S.G & R.M.U using factory-installed lifting provisions.
1.07 COORDINATION:
A. Coordinate layout and installation of M.V.S.G & R.M.U with other
construction and room dimensions. Advise the Engineer in case of conflict.
B. Coordinate size and location of concrete or mounting bases. Concrete
reinforcement, and formwork requirements are specified in Division 3
section "Cast-in-place concrete."
1.08 SPARE PARTS AND TOOLS:
A. Spare Parts:. Provide spare parts, as recommended by the manufacturer, for
one year maintenance as expected under local conditions, and to allow for
emergency replacement due to accidental breakage or failure. Spare parts are
to include, but are not limited to, the following:
4
1. Two sets of each type of lamp, fuse, auxiliary switch, trip coil, control
switch, selector switch, selector switch, neon indicator and the like.
B. Tools and instruments: Provide tools and instruments required for normal
routing inspection, testing, operation and maintenance including levering
crank, manual charging handle, manual shutter operator, testing jumpers and
HV test bushings, set of rail extensions, digital micro ohm-meter, set of
mobile lifting and handling equipment etc. as necessary for the type of
M.V.S.G & R.M.U.
PART 2 ¡VPRODUCTS
2.01 MANUFACTURERS:
A. Available Manufacturers: subject to compliance with requirements, provide
products by one of the following or approved equal:
1. ABB (Sweden/German/Egypt)
2. Merline-Gerin (France/Egypt)
Warranty: Provide a one year warranty for all equipment specified in this
section.
2.02 RING MAIN UNITS:
3. Each ring main unit comprises No.3 three-pole SF6 load break switches
rated 630 Amps for the incoming and outgoing ring main feeders cables,
one three-pole SF6 fused load break switch 630A for the outgoing cable
connected to the M.V.S.G as shown on the drawings. The unit must
comprise measuring compartment including three current transformers and
voltage transformers protected with H.R.C fuses to effect metering the
input electric power by the electricity authority. The three pole load break
switch with fuse shall be provided with tripling coil which shall be activated
by buchloz relay installed on the transformer.
A. Cable termination boxes shall be provided for the incoming and outgoing,
also for the 12 KV switchboard supply feeder.
B. Switch disconnectors shall be manufactured to IEC 298, 294 and 262
category B VDE-67 part 3 and 6 or BS 5227 or any approved equal.
C. They shall be SF6 gas insulated compact ring main unit of IP42 capable of
interrupting safely, their nominal full load current.
D. Busbars: Air-insulated, high conductivity, electrolytic tin plated copper,
modular, designed to withstand worst short-circuit conditions without
allowing permissible temperature rise at ambient conditions to be exceeded,
in accordance with the standards. Busbar connection from one unit of
witchgear to another is to be expansion/contraction compensated, plated
and bolted. Busbar supports are to be flame-retardant, track-resistant, glass
polyester, porcelain or equally reliable fiberglass reinforced epoxy to
approved standards.
5
E. Busbars: Additional epoxy insulation is to be provided to busbars applied
by the fluid-dip process. Busbar connections are to be insulated with easily
installed, performed vinyl boots, secured by nylon hardware.
F. Earth Bus: Copper of not less than minimum size required by the Standards,
designed to withstand worst earth-fault current of power system without
showing any signs of thermal or mechanical damage or degradation. Earth
bus is to extend full length of switchgear.
G. Power Cable Terminations: Fixed bolted type, unless otherwise specified,
complete with standard fittings and accessories for connection of incoming
and outgoing cables. Cable compartment is to be designed to permit cables
to enter enclosure and connect at respective terminals from below, or as
shown on the Drawings. Terminations are to include appropriate sealing
ends, fittings and accessories for type of cable, including stress cones or
other stress relieving accessories, heat shrinkable sleeving, end boxes or
end bushings and fittings of any kind necessary to support and protect
specified cable ends.
H. Earthing facilities are to be provided for earthing and/or short-circuiting the
feeder at its terminals through built-in, safety-interlocked, quick-make
earthing switch, without use of loose attachments.
I. Metal cases of instruments and control devices are to be connected by bare
copper conductors of not less than 2.5mm2 cross-section to nearest earth
bar.
J. Test terminal blocks are to be provided inside insulating covered bases for
instruments, instrument transformers, relays etc. in LV compartments.
K. Components are to be interchangeable when of same rating and function.
L. Finish: Inner and outer surfaces of steel enclosures and structure are to be
cleaned, phosphatized primed with rust inhibiting primer and finished with
two coats of baked enamel, color standard gray (RAL 7033) unless
otherwise approved. Finish is to be vermin and fungus proof and suitable
for worst climatic conditions on site.
M. The switch disconnector shall have the following Ratings:
1. Rated Voltage : 12 kV
2. Nominal Service Voltage : 11 kV
3. Rated Frequency : 50 Hz.
4. Rated One Minute Power Frequency Withstand Voltage (rms) to earth
and between phases : 28 kV
5. Rated Impulse Withstand ¡VVoltage (1.2/50 micro-sec) (peak): 75kV
6. Rated Normal Current of Busbars: (630 A ) as shown on the Drawings.
7. Rated short time withstand-current: 20 kV for 1 second.
8. Rated peak withstand-current : 50 kA
9. Load breaking capacity : 30A at power factor 0.7 and Un
10. Closed loop breaking capacity: 30A at power factor 0.3 and 0.25Un
11. Rated short time current for 1 second:
a. Line blades 50 KA rms.
b. Earth blades 25 KA rms.
6
12. Peak withstand current
a. Line blades 75 KA rms.
b. Earth blades 50 KA rms.
N. The load break switches shall be operated by hand-operated handles
through levers. A protective barriers must be provided to safeguard the
personnel from unintentional contact with the live parts during switching
operations.
Marking labels shall be fitted to indicate the ON/OFF positions of the
switches and the hand-operated handles shall be provided with locks.
Insulating barriers shall be inserted between the open contacts when
working on cables.
O. Earthing switches are to be provided on the feeders side to enable earthing
the cable feeders when working on the cables.
P. Mechanical interlocking between the load break switches and their relevant
earth switches such that no load break switch can be switched on as long as
his mate earth switch is in the ON position and vice versa.
4. Each Ring main unit must be equipped with earth fault indicators of the
type and according to the electricity authority requirements.
Q. Enclosure shall be made of steel sheet 2.5 mm thick before paint and treated
against rust and provided with priming, intermediate and finishing coats of
electrostatic painting powder from inside and outside the external coat is
generally light gray colour.
R. The outgoing circuit breakers shall be able to be controlled via the B.M.S
system
2.03 MEDIUM VOLTAGE SWITCHGEAR:
A. The medium voltage switchgear shall be dead front, self-supporting
structure, consists of line-ups of metal enclosed, air-insulated and
compartmented cubicles. VACCUM type circuit breakers on draw-out
trucks as indicated. The truck is fully interlocked with the interrupter and
the stationary cubicle. It is manually moved horizontally from the "
Operating " to the " Isolated/Test" position without the use of auxiliary
equipment. A fully isolated low-voltage compartment is integrated.
The switchgear cubicles and interrupters shall be factory assembled and
type-tested. All switchgear components should be provided according to
electricity authority requirements.
B. The stationary part of the cubicles are built as a self-supporting structure,
bolted together from rolled steel sheets of at least 2.5mm gauge, rated for
12KV. Each cubical is to be divided into three sealed and isolated
compartments by arc and pressure resistant fiberglass reinforced epoxy
partitions, i.e, the busbar, cable connection and circuit breaker
compartment. The vertical partitions shall carry automatic,
phase-segregated safety-shutters made of insulating material.
These shutters are to seal in both directions, effectively preventing ionized
gases from fault-arcs to spread to the neighboring compartment. Each
compartment shall have its own pressure relief device.
7
C. The interrupter truck shall carry SF6 circuit breaker, with associated
operating mechanism and auxiliary devices. By manually moving the truck
it may be brought into a distinct operating and isolating test position. The
front shield of the truck shall engage firmly with the frame of the cubicle
when locked in the operating position, and become an arc and
pressure-proof part of the enclosure.
D. All protective relays, monitoring and control devices of a feeder shall be
accommodated in a metal-enclosed LV compartment on top of the HV
enclosure. Device mounting plates, cabling troughs, and the central LV
terminal strip(s) shall be located behind a separate lockable door fitted with
a Plexiglas window. Transformer feeder circuit breaker relays shall be fully
coordinated with transformer starting currents of 400¡Ómilliseconds.
E. The busbars shall be rectangular, drawn from pure copper with cross
section area 1200mm2 and shall be mounted on ribbed, cast-resin post
insulators sized to take up the dynamic forces resulting from short-circuits.
The busbar shall have the following specification:
- Rated voltage 24KV
- Nominal operating voltage 22KV
- Thermal withstand short circuit current for 1 second 50 KV
F. Line and load side primary disconnects shall have flat, spring-loaded and
silver plated semispheric pressure contacts for low contact resistance and
good ventilation.
G. Additional Safety Features
A series of sturdy mechanical interlocks shall force the operator into the
only safe operating sequence of the switchgear, preventing positively the
following:
ƒx Moving the truck with the circuit-breaker closed.
ƒx Switching the circuit-breaker in any but the locked "operating" or
"Disconnected/Test" position.
ƒx Moving the truck into the operating position with the low voltage plug
disengaged.
ƒx Engaging the grounding switch with the truck in the "Operating" position,
and moving the truck into this position with the grounding switch engaged.
H. In the "Connected" and the "Disconnected/Test" position of the truck, the
switchgear shall be totally protected against contact with live parts with
objects larger than 1 mm in diameter.
I. The entire switchgear and circuit breakers shall be rated to operate
continuously under full capacity in 45OC ambient temperature conditions.
J. The switchgear parts shall comply with the relevant I.E.C standards
specification regarding design, workmanship and testing.
1. HV metal enclosed or metal clad switchgear I.E.C.298
2. Common clauses for HV switchgear I.E.C 694
3. Circuit ¡V breakers I.E. C 56
8
4. Metering and protective C.T.'s I.E.C. 185
5. Metering and protective V.T.'s I.E.C. 186
6. Relays I.E.C. 255
7. Reading instruments
(ammeters, voltmeters). I.E.C. 51
8. Watt-hour meters I.E.C 521
K. Precaution shall be taken at contacts between aluminum and other material
to avoid electrolytic action.
L. All circuit-breakers on the 12 KV switchgear shall be interchangeable.
Each incoming, outgoing feeder and bus-tie cubicle shall comprise circuit
breakers. The circuit breakers shall be VACUUM type, mounted on
withdrawable trucks, and shall fulfill the following technical specifications:
Type VACUUM
Rated voltage KV 12
Nominal operating voltage KV 11
Rated current:
- Incoming feeders Amps 630
- Bus-tie Amps 630
- Outgoing feeders Amps 630
- Rated breaking current r.m.s. at rated voltage
for 3 second KA 50
- Making current, peak value KA 75
- Dynamic withstand current, peak value KA 75
- Rated operating sequence O-0.3s-CO-3min-CO.
One minute power frequency withstand voltage:
- Phase to earth KV 75
- Phase to phase KV 75
- Through open contacts KV 100
Impulse withstand voltage (1.2/50 £g.s peak):
- Phase to earth KV 125
- Phase to phase KV 125
- Through open contacts KV 145
The circuit breaker is equipped with closing spring charged by an electric
motor operated by 110V AC.
It shall have two electric coils one for tripping and the other for closing.
Circuit breaker opening and closing can be done electrically by push button
at low voltage compartment and mechanically at the circuit breaker.
For ac control, a capacitor trip device is used with each circuit breaker shunt
trip to ensure that energy will be available for tripping during fault
conditions. A control power transformers is required on the sourceside of
each incoming line breaker. Closing bus tie or bus sectionalizing breakers
will require automatic transfer of control power. This control power
9
transformer may also supply other ac auxiliary power requirements for the
switchgear.
Operating spring can be manually charged too. It shall be equipped with a
counter to count the number of operations and an indication of this spring
status.
M. The switchgear shall be constructed so that it corresponds to the degree of
protection IP65 according to IEC publication No. 529.
N. Each cubicle must equipped with space heaters to prevent moisture &
humidity ingress (220Vx2x200W) one in cable compartment and the other
in circuit breaker compartment controlled by miniature breaker and by
hygrostat.
O. All circuit breaker shall equipped with the following:
a. Gas pressure gauge,
b. In case of insufficient gas pressure than the limit assigned by the
manufacturer for proper operation the circuit breaker should be lockout
(blocked).
c. Valve for gas filling and drainage.
P. Switchgear shall consists of the following panels:
1. Two (2) incoming feeder panels.
2. Two (2) outgoing feeder panels.
3. One (1) panel sectionalize.
4. One (1) panel adapter.
Q. The switchgear shall be of the totally enclosed indoor type, of size, rating
and arrangement as shown on drawings and indicated in the specification.
The complete assembly shall be floor mounted, free standing, with
matching cases, to form a continuous integral structure. The housing shall
consist of folded sheet steel sections welded together and shall be of robust
construction. Switchgear shall have front and rear access.
10
R. Direct panel to panel busbar connection shall be made without the use of
interconnecting links.
The arrangement shall permit cables to enter from the bottom of the
enclosure and connect at their respective terminals without interference.
S. Cable termination boxes shall be provided for incoming and outgoing
feeders having 1-core, armored XLPE insulated, Copper cables of 300 sq.
mm. cross sectional area for outgoing feeders and 1-core, armored XLPE
insulated, copper cables of 300 Sq. mm cross sectional area for incoming
feeders.
T. Facilities shall be provided for earthing the feeder side of the circuit breaker
without the use of loose attachments.
U. Finish shall be battle ¡Vship gray, "or any other colour approved by
Engineer", vermin-proof and suitable for the climatic conditions of the site.
V. Each switchgear unit shall be provided with a metal rating and name plate
giving the required particulars in accordance with the IEC
recommendations.
W. Instruments and meters shall be of the flush pattern with phenolic-black
finish digital type.
Relays shall be of the flush fixed pattern digital type.
Test terminal blocks shall be provided for all instruments, relays ¡Ketc.
X. Incoming Feeder Panels:
Shall be equipped with the following components:
ƒx One withdrawable, motor operated, SF-6 type circuit breaker rated 630 A,
with 50 KA short circuit breaking capacity.
ƒx One set for busbars rated 800 A and designed to withstand
electrodynamics forces under worst short circuit conditions of 50 KA.
ƒx Three current transformers each with separate secondaries for metering
and protection.
Accuracy class : 0.5 M5 for metering
5P 10 for protection
Ratio : 300-600/5/5A
ƒx Indicator lamps.
ƒx Three ammeters with scale 0-300-600 A and accuracy class 2.
ƒx One voltmeter scale 0-12 KV class of accuracy class 2 with selector
switch.
ƒx K.V.A.R ¡V meter, for three phase, 3 wire unbalanced loads, class 3 rating
110V/5A to operate from the secondaries of voltage and current
transformers.
11
ƒx Ditto but KW ¡Vmeter, but with class 1 and with maximum demand
indicator.
ƒx Power factor meter.
ƒx Two push buttons on and off.
ƒx One three phase non-directional over current relay with definite time delay
characteristic:
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.5-3.5) In
d. Current steps 0.1 In (up to 2 In)
e. Time setting range (0.1-3) sec
f. Time steps 0.1 sec
g. The relay must has a flag or LED on its face to indicate relay
operation.
h. High set over current (short circuit) element:
1. current setting range 2-10 In/¡Û
2. Time setting range (0.04-2) Second.
3. Time steps 0.05 up to first 0.3 secon
12
i. Output contacts 2 normally open contacts at
least each 5A rating
ƒx Non-directional earth fault relay definite time characteristic.
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.1-0.5) In
d. Current steps .0.1 In
e. Time setting range (0.1-3) sec
f. Time steps .0.1 sec
g. Output contacts 2 normally open contact at least
each 5A rating
h. The relay must has a flag or LED on its face to indicate relay
operation.
ƒx Three phase directional over current relay:
For phase-phase faults with the following specifications.
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.2-1) In
d. Current steps 0.1 In
e. Time setting range (0.05-3) sec
f. Relay internal angle 30O ¡Û60 O
g. Output contacts 2 normally open contacts each
5A rating
h. The relay must has a flag or LED on its face to indicate relay
operation.
ƒx Directional earth fault:
For phase-to earth faults with the following specifications.
a. In =5A
b. Aux AC power supply 110V AC ¡Ó15%
c. Current steps range (0.1-0.4) In
d. Time setting range (0.05-3) sec
e. Time steps (0.05) sec
f. Relay internal angle 0-90 O with steps not more than 15 O
g. Output contacts 2 normally open contacts each
5A rating
h. The relay must has a flag or LED on its face to indicate relay
operation.
ƒx Three under voltage relays adjustable between 30-80% of rated value.
(time delayed).
Relay characteristic must be coordinated with and approved by the Electric
Power Authority
ƒx Earthing switch
13
Y. Outgoing Feeder Panel.
Shall be equipped with the following components:
ƒx One withdrawable, motor operated, VACUUM type circuit breaker rated
630A, with 50 KA short circuit breaking capacity.
ƒx One set of insulated busbars rated 1200 Amps and designed to withstand
electrodynamics forces under worst short circuit conditions of 25 KA.
ƒx Three current transformers with separate secondaries for metering and
protection
Accuracy class : 0.5 M5 for metering
5P10 for protection
Ratio : 200-400/5/5 A
ƒx Indicator lamps
ƒx Three ammeters with scale 0-200-400A and accuracy class 2.
ƒx One three phase none directional over current relay, same specifications as
that for incoming feeder.
ƒx Non directional earth fault relay, same specifications as that for incoming
feeder.
ƒx Earthing switch.
Z. Bus Sectionalize Panel:
Shall be equipped with the following components:
ƒx One withdrawable, motor operated, SF-6 type circuit breaker rated 630A,
with 50 KA short circuit breaking capacity.
ƒx One set of insulated busbars rated 1200 A, and designed to withstand
electrodynamics forces under worst short circuit conditions of 50 KA.
ƒx Three ammeters with scale 0-600 A and accuracy class 2.
ƒx Three current transformers for protection:
Ratio : 600-1200/5/5 A
Accuracy class : 0.5 M5 for metering
5P10 for protection
ƒx One three phase none directional over current relay, same specifications as
that for outgoing feeder.
ƒx Electrical interlock between the incoming & bus coupler circuit breakers
shall be provided as follows:
a. Bus tie circuit breaker is normally switched off while the incoming
feeders circuit breakers are switched on.
b. If the incoming feeders circuit breaker in any section are switched off,
then the bus tie circuit breaker can be switched on.
c. If one of incoming feeders circuit breakers in any one or in the two
sections is switched off the bus tie circuit breaker can be switched on.
d. Mechanical interlocks prevent the following faulty operations:
- Insertion or withdrawal of a closed CB.
- Closing of breaker not locked in service or test position.
- Closing of earthing switch with breaker in service position.
- Breaker insertion with earthing switch closed.
- Breaker insertion with LV plug not connected.
14
ƒx Circuit breaker mechanism shall have an anti pumping relay.
ƒx Enclosure heater.
AA. Tests:
1. Supply test results to confirm that the switch has been tested to
substantiate designs according to applicable standards verifying not only
the performance of the switch and integrated switch-fuse assembly, but
also the suitability of the enclosure venting, rigidity and bus bracing. In
addition, factory test each switch in accordance with approved
standards.
2. All tests shall be carried out by the manufacturer at works and at his
expense and under control and supervision of electricity Distribution
Company.
BB. Equipment Data
Equipment data for materials covered under this section shall include but
not be limited to the following:-
Construction and installation details for the main 12 KV switchgear
equipment.
Floor plan and top view showing outline dimensions and arrangement of
cubicles.
Details of connection of high voltage cables to the cubicles.
Wiring and schematic diagrams of power, control, relay, metering and
similar circuits. The separate schematic diagrams shall include complete
three line diagrams of all instruments, switches, any other devices in the
12KV switchgear Handling, installation and assembly drawings.
Key interlocking scheme showing key numbers and operations performed
The equipment data to be provided prior to ordering any material covered
by this section shall include but not be limited to the following:
Complete technical data on the 12KV switchgear other equipment
including data on operating characteristics, compliance with standards,
dimensions and sights, detailed description operating mechanism etc.
CC. M.V to be provided with special key lock and accordingly master key shall
be valid for all panels at plant.
DD. Color of M.V panel (RAL 7032).
Complete technical data on instruments protective and auxiliary relays,
measuring instruments including manufacturer's atalogues operating
characteristics, operating curves, detailed description etc.
EE. DC batteries system and all electricity authority requirements.
FF. All bus bars shall be electrical copper of section not less than 400 mm2,
mounted on support insulators enough to withstand mechanical forces,
which may happen due to short circuit 50kA r.m.s. at 12kV for l sec.
15
GG. Each switch compartment shall be equipped with suitable clamp or any
other mean for supporting and fixing the cable or end box.
HH. All wiring shall be in PVC conduits..
II. Automatic reset type complete with ferranti current transformer, which will
be erected around the cable sheath, according to the specification and Shall
be mounted inside a metal or fiber-glass box with an opening to show the
indicator flag.
JJ. Control and monitoring of each unit is to be provided on front panel and is
to include mimic diagram, operating handles of main device and earthing
switches, position indicators, potential indicators, identification and
instruction plates, protective devices, metering and indicating instruments,
key and padlockable devices, as specified and shown on the drawings.
KK. Access to LV wiring is to be from front of cubicle for control, protection,
test terminal blocks and associated LV power connections. Multi-pin,
disconnectable, lock-in type plug and socket arrangement is to be provided
between circuit breaker and stationary part of cubicle.
LL. Anti-condensation heaters with thermostat, switch and pilot lamp and of
rating recommended by manufacturer are to be provided in each section of
switchgear assembly.
MM. Wiring diagram, suitably protected and located inside LV compartment
of each unit, is to indicate all data and components related to the particular
unit and its external circuitry.
NN. Insulating Mat: Anti-slip, synthetic, insulating, rubber mat, minimum
5mm thick and 900mm wide, with heavy canvas lining on lower face, is to
be provided for full length in front of switchgear assembly.
OO. Accessories are to include the following:
1. 2 N.O and 2 N.C; auxiliary contacts on each switch.
2. Automatic reset earth fault indicator operated by core-balance type CT
located near and outside cable terminals and visible from front.
3. Insulating rubber gloves, earthing equipment, fuse tongs, schematic
diagram with equivalent ratings and references, operating handle etc.
placed inside compartment.
4. Shunt trip relay on fuse switch combination, operated by push buttons or
relay, using auxiliary power.
5. Under-voltage relay, operated by auxiliary power electrical closing
devices, geared motor connected to switch spring charging mechanism,
with closing release, operated from auxiliary power supply.
6. MV fuses: High-breaking capacity, totally enclosed, cartridge type fuselinks,
current limiting, with striker pins to cause switch to open. Fuses
are to comprise fuse links and fuse bases insulated to respective
standards.
16
2.04 MV CIRCUIT BREAKERS:
A. Type: VACUUM circuit breaker using rotating are or puffer principle, with
closed gas circuit, and with pressure detector to prevent operation of circuit
breaker in case of loss of gas pressure within the sealed enclosure. Sealed
enclosure is to be stainless steel.
B. VACUUM breakers, are to be provided with gas filling valve and with
pressure switches, one per pole to initiate alarm in case the pressure of the
VACUUM gas drops below manufacturer set values. Alarm serine is to
provided to initiate alarm.
C. Operating Mechanism: Mechanically and electrically trip-free, stored
energy, spring loaded, manually charged by lever or hand-crank,
electrically charged by suitably rated universal motor, and capable of one
complete off-on-off cycle in case of loss of control power. Circuit breaker is
to have electrical close solenoid and two trip coils, mechanical on and off
push buttons, mechanical on/off/charged indicators, operation counter and
auxiliary switches to satisfy all functions specified or shown on the
Drawings. Five N.C. and five N.O spare auxiliary switches for future use
are to provided in addition to those required. Insertion of manual spring
charging lever or hand-crank is to automatically disconnect the motor. Slow
closing of circuit breaker contacts for inspection and adjustment is to be
possible whilst in the disconnected position.
D. Automatic tripping is to be by indirect auxiliary power through CT operated
protective relays.
E. Interchangeability: Circuit breakers of different current ratings are not to be
interchangeable. Circuit breakers of same current rating are to be wired
alike and interchangeable.
2.05 INSTRUMENT TRANSFORMERS AND CONTROL SWITCHES:
Instrument transformers shall be sized for burden requirements of connected
meters with accuracy class as follows:
CURRENT TRANSFORMERS (CT's):
Class 0.5 for metering and 1.0 for protection n.10
POTENTIAL TRANSFORMERS Metering - Class 1.
All potential transformers shall be provided with current limiting fuses. Voltage
rating for the secondary winding shall be of ratios:
12000 / 110 / 110 /
¡Ô 3 ¡Ô 3 3
For metering and protection the thermal rating of the transformers shall be
sufficient to provide the total current required to operate the burdens on the
secondaries without exceeding the rating of transformer as indicate on nameplate.
PT's (1 per phase) shall be installed either as a unit drawout assembly or with an
isolating switch in a separate compartment to that the transformers, primary fuses
and secondary circuits may be inspected and tested in a completely de-energized
condition. CTS shall have mechanical and thermal rating equal to the rating of the
circuit breaker and LBS. secondary rating shall be 5 amperes and primary ratings
17
shall be as shown on one-line diagram. Transformer shall be capable of carrying
120 percent of rated current for one hour. Ground current sensing transformers
shall have a one-ampere secondary current.
Control switches shall be the rotary enclosed type with positive means for
maintaining contact position.
2.06 ACCESSORIES
A. Signage:.Each R.M.U and M.V.S.G shall have engraved laminated
nameplates screwed to the doors of each individual compartment and
wiring diagrams pasted inside each door.
Each M.V.S.G & R.M.Us shall be furnished with a sign marked
"DANGER ¡V HIGH VOLTSGE" Letters shall not be less than 25mm
high, 6mm stroke. Signs shall be laminated plastic, red letters with a white
background.
All compartments with voltages from sources outside of the compartment
shall have a sign on the compartment door marked "CAUTION ¡V THIS
UNIT CONTABINS A VOLTAGE FROM A SOURCE OUTSIDE OF
THIS UNIT". Letters shall be black on a high visibility yellow
background. Signs shall be adhesive backed vinyl approximately 75mm
by 125mm.
All nameplates and signage shall be printed in both English and Arabic.
PART 3- EXECUTION
3.01 INSTALLATION:
A. Locations and Layout: Exact locations and physical layout of equipment and
components may be varied as required to suit manufacture's design and as
approved, provided the required functions and operations are accomplished,
follow the identification of the units indicated on drawings exactly to ease
checking and building maintenance procedures.
B. Equipment Bases: Ensure that concrete bases and foundations provided for
installation of equipment are constructed in accordance with approved shop
and construction drawings and equipment manufacturer's drawings and that
holes for fixing bolts and provisions for passage of cables etc. are provided as
required.
C. Cable Trenches: Ensure that trench construction and covers provided for
installation of power and control cables are in accordance with approved shop
and construction drawings.
[
D. Built ¡VIn Items: Ensure that equipment supports, fixings and the like, and
sleeves for passage of feeders and cables which are to be built into concrete
foundations, bases, cable trenches or building structure are provided as and
when required and that they are properly installed.
E. Equipment: Install on concrete bases etc. and assemble completely plumb and
level, before grouting in holding-down bolts.
F. Supports and Terminations: Install all incoming and outgoing cable supports,
cable ends and termination fittings required for MV, LV and control cables
18
G. Relays: Set in accordance with manufacturer's instructions and the local
power authority requirements.
H. Earthing: ensure that earthing installation is as described in Division 16
Section "Earthing" of the Specification and/or as shown on the Drawings.
I. Temporary Lifting provisions: Remove temporary lifting eyes, channels
brackets and temporary blocking of moving parts from switchgear units and
components.
3.02 IDENTIFICATION.
A. Identify field-installed wiring and components and provide warning signs as
specified in Division 16 Section "Basic Electrical Materials and Methods.
B. Diagram and Instructions: Frame under clear acrylic plastic on the front of the
M.V.S.G & R.M.Us.
1. Operating Instructions: Printed basic instructions for R.M.U & M.V.S.G.
2. Storage for Manual: Include a rack or holder, near the operating
instructions, for a copy of the maintenance manual.
3. System Power Riser Diagrams: Depict power sources, feeders
distribution components and major loads.
3.03 CONNECTIONS:
A. Tighten bus joint, connector and terminal bolts according to manufacturer's
published torque-tightening values. If manufacturer's torque values are not
indicated, use those specified in applicable Standards.
3.04 FIELD QUALITY CONTROL:
A. Equipment: Inspect equipment upon delivery to site and report any damage
to the Engineer.
B. Switchgear: Inspect and check switchgear for completeness and as
recommended by the manufacture and check phasing of buses, contact
alignment and clearances.
C. Components: Check component ratings, types, sizes and wiring connections
including current and voltage transformers, fuses, switches instruments and
relays.
D. Before energization carry out at least the following tests:
1. Insulation resistance on busbars (with circuit breakers in disconnected
position) circuit breakers bushings and insulators feeder terminals etc.,
using at least a 5 kV megger for MV circuits and a 1000 V megger on all
control and protection circuit with relays lamps and the like components
disconnected, to ensure satisfactory insulation resistance as
recommended by the Standards and approval practices.
2. High voltage tests on busbars circuit breakers in disconnected position
switches, VTs and insulators by applying HV a.c test voltage between
phases and phase to earth at 80% of the IEC voltage withstand test for
1-minute.
19
3. Resistance across closed contacts of circuit breakers using appropriate
micro-ohm meter.
4. Polarity check and ratio tests for CTs.
5. Calibration checks and adjustment for ammeters and voltmeters.
6. Primary and/or secondary injection tests to check relay operation suing
appropriate test sets, followed by tripping of circuit-breaker once only,
through its protective relay circuit.
E. Cables: with circuit breaker in disconnected position, ensure that HV testing
of feeder cable and respective termination is carried out as required under
cable tests.
F. After energization a carry out inspection and checking as follows:
1. Breakers are to be closed one at a time with as little load on the feeder as
possible, check meters as load is increased and any indication of
overheating detected by appropriate instruments or sensors.
2. Open and withdraw circuit breaker after a prolonged test run, inspect and
check circuit breaker conditions isolating contacts, contacts on all
instruments and control switches, connections at terminal blocks etc.
busbar connections and busbar for any indication of overheating check for
loose connections and bolts etc. and finally re-apply megger tests to ensure
same quality of insulation as before energization.
3. Close circuit breaker slowly, while in the disconnected position and
inspect contacts and/or contact movement and compare with design
figures.
G. Manufacturer's instructions are to be followed under all circumstances.
Carry out and record measurement and tests recommended by the
manufacturer.
3.05 CLEANING:
A. Inspect interior and exterior of installed switchgear. Remove paint-splatters
and other sports, dirt, and debris. Touch up scratches and mars of finish to
match original finish.
B. Vacuum ¡V clean all interior equipment.
END OF SECTION 16343
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