Specifications of Substation equipment and Generating
Set
for Bangladesh
GENERAL
SPECIFICATION:
The specification for the parts of this
contract mentioned below cover design, manufacture, assembly and
testing at the
contractor’s workshop as
well as the
supply, delivery, installation,
testing and commissioning of the sub-station
equipment at site.
CLIMATIC
CONDITIONS:
The climate is tropical and has marked
Monsoon character with seasonal changes from humid, warm, rainy season ,
summers to cool and dry winters. Maximum temperature occurs during the period
from April to May reaching approximately 43 deg. C (110 deg.F) with a relative
air humidity of 60% to 70%.
The annual mean temperature is approximately
29 deg. C (84 deg.C). During the rainy monsoon month from June to September,
the average relative air humidity is 80% and reaches extreme values upto
saturation point during longer periods. the annual rainfall, most of which
occurs from June to September is 2000mm to 2500mm.
OPERATING
CONDITIONS:
The sub-station equipment will be connected
to the 11KV, 3-phase, 50 Hz Bus of Power Development Board/REB/DPDC/DESCO Bangladesh.
STANDARDS:
All equipment and materials must be in
conformity with the most recent relevant Bangladeshi laws, standard rules and
regulation. Particular attention is to be paid to the Electrical Act 1910 and
Electricity Rules 1937 (as amended in 1946). All equipment and materials to be
supplied, which required any Form of approval by the Bangladesh Government or a
Local Authority like PDB/DPDC/DESCO/REB or equivalent must satisfactorily pass
all inspection and tests procedures imposed by them.
Otherwise, all the equipment and materials
must be in conformity with the most recent international rules, regulation,
standards and recommendation: IEC.
STANDARD
DATA:
The following standard values for high and
low voltage are standard in Bangladesh.
DISTRIBUTION BUS HIGH VOLTAGE : 11KV, MAXIMUM SYSTEM VOLTAGE 12 KV.
LOW VOLTAGE : 415/240V LOCAL VOLTAGE
400/231-OPENING VOLTAGE
457V -MAXIMUM PERMISSIBLE
VOLTAGE BY PDB/DPDC/DESCO/REB
FREQUENCY:
The standard power frequency in Bangladesh
will be: 50Hz.
DESIGN
& CONSTRUCTION REQUIREMENTS:
All equipment are to be in accordance with
the latest recognized rules of workmanship and modern engineering practice.
All parts of the equipment must be suitable
in every respect for continuous operation at maximum output under the climatic
conditions as specified above.
MARKING OF
TERMINALS:
The terminals shall be marked in accordance
with BS, IEC, VDE or equivalent standards.
PAINTING:
Protective painting shall be done in
accordance with general practice and recognized methods, the paint
manufacturer’s instruction and according to the present addition of DIN 55 928,
CORROSION PROTECTION OF STEEL STRUCTURE’ such as to meet the tropical condition
at site.
EARTHING
OF EQUIPMENT:
Each electrical equipment must be provided
with an earthing screw of sufficient diameter or an earthing plate.
INSULATION
CO-ORDINATION:
The insulation level for load break switch,
lightning arrestor and transformer are stipulated below, taking into account
the maximum service voltage and the rated voltage according to IEC standard,
with appropriate impose withstand test voltage and power frequency withstand
test voltage values.
The insulation levels for equipment are as
follows:
According to IEC rated service voltage : 11KV
Maximum service voltage shall be considered : 12KV
The respective test voltage shall be :
Impulse withstand test voltage (BIL) : 75KV
Power frequency withstand test voltage : 28 KV
For the lightning arrestor, the IEC standard
voltage of 9KV is to be selected.
TECHNICAL
REQUIREMENTS:
The equipment specified in the following
items shall withstand the impulse levels and test voltages specified by the
recommendations of IEC, as stipulated before. They must be capable of carrying
the short time current for three seconds and must withstand the short circuit
(Peak value) current.
The rupturing capacity of the circuit
breakers is indicated in the respective items. The switchgear must be designed
accordingly in order to withstand the mechanical short circuit stresses.
They must contain all technical particulars
which are mentioned in the Schedule of Technical Data.
The Owner reserves the right to have routine
tests carried out on each type of equipment at the manufacturer’s workshop in
the presence of his representative.
HIGH
TENSION SWITCHGEAR:
SCOPE:
The switchgear shall be pre-fabricated,
complete and ready for erection and suitable for indoor installation.
STANDARDS:
11KV switchgear must comply with the requirements
of IEC 694,VDE0101,0670 Part-6 74(draft), 0670 Part-7 74(draft) IEC
republication 298.69 Pahls recommendation No.2 and equivalent British Standard
(BS 116-1952) 11KV Switch Board shall be consisting of cubicles free standing
type, for indoor installation, formed by pre-fabricated factory assembled. The
individual cubicles shall be made of strong sheet steel (min16SWG) at all sides
with iron angles and channels welded
together.
The board shall be covered and the top shall
be provided with pressure relief, flaps the bottom shall be open the allow
connection of cables via and boxes, necessary holding iron and clamps are
provided.
The front shall be provided with sheet steel
doors with special locking devices and with viewing glasses in order to see the
condition of the switches and the contact.
On the top of the cubicle a sheet steel
enclosed relay, meter cabinet shall be provided.
The iron and sheet steel parts after cleaning
by modern methods shall be painted in the initial layers and a final paint as
such the lacquer shall be a protection against corrosion the tropical humidity.
The final colour of the cubicles will be pebble grey to DIN 43656. The single
busbar system shall be of copper bars to withstand the required amperage. They
are to be mounted on cast resin insulators in each cubicles.
The single bars shall be marked by the
colours as per IEC, VDE or BS standard.
CIRCUIT
BREAKER
The circuit breaker must comply with VDE
specifications 0670, Part-102, IEC Recommendations and Publication 56, IEC 695,
BS 116, BS 5311 or equivalent ANS & UTE Specifications.
Technical data for circuit
breaker
Nominal System voltage : 11 KV
Rated normal current : 630A
Number of phases : 3
Frequency : 50 Hz
Rated short circuit breaking current(rms) : 25KA
Rated short circuit making current duration :
3 sec.
Rates short circuit making current : 50KA
D.C component of rated short circuit breaking current : 36%
Rated lightning impulse withstand voltage : 75
KV
Rated Power frequency withstand voltage (60 sec) : 28 KV
No. of operation cycles at the rated normal current : 20,000
No. of operation cycles at the rated short circuit current : 100.
CURRENT TRANSFORMER:
Current transformer must comply with BS 3938,
VDE 0414 and IEC 185.
The C.T. should be cast resin insulated with
class 10P10 for protection and class 0.5 for metering. The rated over current
factor and burden should be matching with operating burden of the connected
equipment to prevent the instruments from being damaged, 1th = 80xIn, id=200 In.
POTENTIAL
TRANSFORMER:
Potential transformer must comply IEC86,. The
P.T should be cast resin insulated with appropriate accuracy class and burden
minimum 50VA. The P.T. secondary shall be protected with MCB.
IDMT
RELAY:
The relay for over current and earth fault
protection should be of solid state (micro-computer operated) type. The
complete triple pole, solid state IDMT relay with adjustable minimum setting
for over current earth fault and short circuit protection including the
A.C./D.C. converter.
This module can be housed in a standard case for assembling in cubicles. The socket which
are located in either the rack or the case in which the module is plugged,
should have one screw and one snap-on terminal each for the plant connections.
The heavy duty current plug connector should be provided automatic shorting of
the C.T. circuits whenever the module is withdrawn. A make-before-break earth
contact should be there to ensure protective earthing, before the other plug
connections can be made.. The relay should be suitable for d.c. shunt tripping
to be operated by 110V D.C. voltage from P.T. secondary through a rectifier or
12/24V d.c. through capacitor rectifier circuit.
Wiring inside the cubicles shall be minimum
1.5mm2 area and with tinned copper conductors. Current circuits shall be made
with minimum 2.5mm2 area and with tinned copper conductors.
All cubicles, frames, transformers, measuring
and relay circuits shall have protective earthing. Each cubicle shall be
provided with earthing bolt and earthing parts.
The busbars shall be of copper and fully
insulated through their length.
The protection system shall consist of over
current protection and earth fault protection.
The bidder shall enclose details of system be proposes, along with
single line diagram, detailed technical specification and mode of operation of
protection system, with his offer
Complete physical dimensions and electrical
characteristics of the equipment offered shall be furnished along with the
offer.
GENERAL
SPECIFICATION OF 11KV SWITCHGEAR:
Nominal System Voltage KV 11
Highest Voltage for Equipment KV 12
Type of Switchgear LBS/VCB/SF6
Class of Switchgear Indoor
Metal clad
Number of Phases 3
Frequency (Supply) Hz 50
Busbars Three
Phase
Rated
short circuit capacity
a) Symmetrical
Breaking Current kApms 25
b) Making
Current kApms 50
Short Time Current kApms 20
Short Time Current Duration Seconds 3
System Neutral Earthing Effective
Rated
Current
a)
Busbars
Amperes Min 800
b) Vacuum
Circuit Breaker Amperes Min 630
Rated
Insulation Level
a) Impulse
Withstand Voltage to Earth KV 75
b) Impulse
Withstand Voltage between Phases KV 75
c) Minimum
Dry Power Frequency Withstand Voltage KV
rms 28
Voltage
Transformer
a) Rated
Primary Voltage KV 11
b) Rated
Secondary Voltage V 110
c) Rated
Output/Phase VA 50
d) Accuracy
Class
0.5
THREE
PHASE POWER TRANSFORMER:
The Transformer shall comply with IEC726, VDE
0532 etc. and the general specifications will be as follows:
Oil immersed Indoor/Outdoor Type Power
Transformer:
a. Rated capacity : As per Schedule KVA
b. Rated
frequency :
50 Hz
c. Rated primary
voltage : 11
KV
d. Rated
secondary voltage : 0.415KV
e. Tap changing (
off load) : ±
2.5%, ± 5%, ± 7.5%
f. Phase
connection :
DYN 11.
g. L.V. neutral : Brought out
h. BIL level
(H.T. side) : 75KV (H.T. side)
i. Maximum
system voltage : 12KV (H.T. side), 0.5 KV (L.T.
side)
j. Cooling :
as per schedule.
The Tenderer shall furnish following data at 75 deg. C.
a. Iron loss at
rated voltage and frequency
b. Copper loss (including supplementary eddy current loss )
at continuous rated current (50 c/s) and for winding at 40 deg.C ambient temperature
with the changer in middle position.
c. Impedance
voltage with tap changer at middle position.
d. Voltage drop referred to rated voltage at rated load
with tap changer in middle position and at unit p.f.
e. Permissible maximum symmetric three phase short circuit
current referred to rated current.
f. Rated no load
current (RMS value referred to rated current).
g. Type of
windings with conductor materials.
h. Class of
insulation material.
i. Voltage
regulation.
j. Temperature after continuous rated load at 40 deg. C
ambient temperature.
In windings
Core
k. one minute
double power frequency induced tests voltage applied to:
H.V. line
terminal
L.V. line
terminal
L.V. Neutral.
l. Impulse test voltage 1.2/50 micro second fully wave positive and negative
polarity applied to:
H.V. line terminal
L.V. line terminal
L.V. Neutral
m. Weight of:
Iron core
Copper
The transformer shall be designed and
manufactured in accordance with the requirement of B.S. 171: 1970 equivalent.
LOW
TENSION SWITCHGEAR:
The Low Tension Switchgear shall be
pre-wired, free standing and Type conforming to IEC 439-1.
SWITCHGEAR
DESIGN:
The switchgear shall be pre-fabricated,
complete and ready for erection on the site.
The switchgear shall be totally enclosed. All
line parts shall be adequately and efficiently protected against accidental
touching.
The switchgear cubicles shall conform to
relevant provisions of BS/IEC and shall be adequate in all respect to
accommodate the cables, switchgears, meters, cable terminations and inter
connection as indicated in the schedule/specification/drawings and be with
provided lockable doors. All apparatus and other components shall be easily
accessible from the front as required for inspection, replacement and repair.
The switch gear shall be of tropical design.
The Switchgear shall
conform to the specifications
Operating Voltage : 0.415KV, 3-phase at 50 Hz.
Voltage system : Direct earth
Number of bus bar :
5 (L1, L2, L3, N & E)
Rated current of bus bars : As per schedule
Bus bar materials :
Copper
Degree of protection of busbar chamber : Enclosed
Maximum protective current
(cos Q = 0.2, t=0.1 sec) of busbar : 80KA
Maximum short time withstand current of busbar : 63KA
Maximum protective peak current of busbar
: 150 KA.
All parts of the switchgear including
apparatus shall be designed to withstand without being damaged, the mechanical
and thermal, strain of this current or, where protected by circuit breaker, the
interrupting current of the circuit breaker.
Outgoing cables shall be arranged in separate
specious cable spaces.
Protective screens shall, as far as possible,
be arranged between main busbars and cable space.
Terminals for power cables shall be protected
against accidental touching.
Interior control wiring shall be accommodated
in plastic conduits.
Wiring inside the cubicles shall be made with
minimum 0.75mm2 area and with tinned copper conductors.
The Switchgear shall be suitable for busbar
entry from the top, if required as per schedule.
APPARATUS:
The switchgear shall be arranged in
accordance with the attached principle drawing.
The switchgear shall be of modular type
design. The apparatus of each functional group shall be assembled on a common
base.
Coils for contractors must be of open type to
be repairable.
CUBICLE
CONSTRUCTION:
The distribution sections shall be of carcase
construction and the carcase shall be augmented with various cladding plates as
required.
The top plate, bottom plate and side plates
shall be polled for easy removal.
The door shall be IP23 for distribution
sections and IP54 for bottom plate respectively. Creep age and clearance paths
shall conform to VDE 0110 insulation group C or UL508 cable 18.1 and BS 162
table 4.
The electrical equipment inside the panel
shall be finger proof. The cubical shall be dust vermin proof.
CABLE
ENTRIES AND TERMINATIONS:
The distribution board shall be so designed
that the cable are fed in and connected in the base. The bottom plate shall be
split and removable type to facilitate cable entry having cable grommet.
All cable socket for incoming and outgoing
cable are to be provided.
CURRENT TRANSFORMERS:
All current transformers shall comply with
IEC 185 /BS 3938 and shall be of suitable class, rating and accuracy depending
on the duty.
INDICATING
LAMPS:
Panels shall have indicating lamps as
specified.
AIR-CIRCUIT
BREAKERS / MCCB:
The air-circuit breakers / MCCBs shall comply
with IEC 947, 157 BS 4752.
The breaker shall have spring assisted manual
closing mechanism with, breaker closing speed independent of operator. There
shall be breaker closed opened position indicator manual tripping shall be by
push button and it shall not be possible to trip the breaker by means of the
closing mechanism. Over load release shall trip the breaker by means of the
closing mechanism. Over load release shall trip the breaker on over current or
short circuit. The time lag for these released and the current setting shall be
adjustable.
CIRCUIT BREAKERS:
The MCB/MCCB’s shall be quick-make,
quick-break, trip free, indicating type and shall have inverse time limit
characteristics with adjustable overload, adjustable short circuit (the maximum
adjustable limit should be as per schedule) and instantaneous magnetic trip
elements functioning on overloads above the normal operating range. All circuit
breakers shall be in accordance with schedule. All lugs must be of the solder
less above the normal operating range. The MCB must comply with IEC 157-1, IEC
898 rated voltage 240/415V, A.C. 50 Hz. interrupting capacities minimum 6 KA
current limiting class 3, finger proof, protection through Thermal and Magnetic
Trip sections respectively, temperature rating 40 deg.C preferably tropicalized
(moisture fungus corrosion treated), with contacts of silver alloy, terminal
capability as per requirement. The MCCB must comply with IEC 947, 157-1 having
rated voltage 600V A.C. 50 Hz with thermal overload and instantaneous magnetic
tripping action, temperature rating 40 deg.C preferably tropicalized (moisture-fungus-corrosion
treated), terminal capability as per requirement. The bidder may offer MCCB
instead of MCB to meet requirement of the specifications.
AUTOMATIC
REACTIVE POWER CONTROL EQUIPMENT WITH CAPACITOR BANK:
The
Power Factor Improvement Plant shall be
sheet steel clad dust and vermin proof free standing, floor mounting
indoor
type. The centrally controlled automatic PFI Plant will be of compact
design
and will be suitable for operation in 12 steps in the system for
automatic
control of the reactive power. The PFI plant shall be consisting of
required capacity KVAR, 415V, 50 Hz, self healing non-PCB, capacitor
bank
with disconnecting switch with fuses of
proper rating, discharge resistors required nos. suitably rated
air-breaker
contractors and associated control unit. The contractors shall have
special
non-welding contacts which can control inrush current of upto 180 times
the
rated current. When the contractors drops out the resistors shall be
switched
on the capacitor by means of two break contact. The control unit shall
be an integral part of the PFI
Plant and will be comprised of C.T. of
adequate rating automatic power factor correction relay to keep the
automatic
power indicating lamp ON/OFF switches, switching step indicator etc. PFI
panel
shall be of a type conforming to IEC 439-1 from manufacturer having ISO
9001.
The automatic control must be non-responsive in a certain range to
element
hunting.
BUSBAR
TRUNKING SYSTEM (OPTIONAL):
The low impedance prefabricated sand witch
type main busbar trunking system shall conform to IEC 439/1-2, tested Siesmic
standard shall be suitable for use in installation conforming to IEC 364.
The busbar trunking system shall be
comprising of (i) two piece aluminium enclousure (ii) Straight length (iii)
Fixing brackets (iv) Elbows (v) Bends
(vi) closed type transformer connection unit (vii) distribution board
connection unit (viii) tap-off boxes with MCCB etc.
SPECIFICATION OF BBT
SYSTEM:
1. Standard : IEC 439-1 &
2, KEMA certificate
2.
Housing
: 2-piece aluminium (no duration
till 55deg. C)
3. Maximum
ambient temperature : 40 Deg.C
4. Degree of
protection : IP54
5. Colour : Approved colour
6. Rated
insulation voltage : Maximum 600 V.A.C.
7. Frequency. : 50 Hz.
8. Rated current
at 40 deg.C : As per schedule
9. Minimum rated
surge
capacity (KA)(t-0.1s) : To be quoted by the bidder.
10. Inherent short
circuit
capacity (KA)
(t-0.Is) : To be quoted by the bidder.
11. Rated short time
with-stand
current(KA)
(t= 1 sec) : To be quoted by the bidder.
Insulation : Mylar
from Du-pont or epoxy insulated-Class B 130deg.C
12.
Busbar materials
: Aluminium
and all conductors tinned
and insulated
13. Busbar cross
section : To be mentioned by the bidder
14. Special features : Single bolt clamping.
15. Others : Drawings
to be submitted for the proposed
BBT system with
detailed information, dimension,
list of materials as per site requirement.
Tap-off units must be designed in such a way
so that the tap-off units can be fitted or removed while the system i.e. the
main busbar trunking is energized.
Circuit breakers in the Tap-off units shall
be of quick make, quick break, trip-free indicating type having adjustable
thermal over-current and adjustable instantaneous electro-magnetic short
circuit release having the rated interrupting capacity.
All the components of the BBT i.e. main
busbar length, reduction unit, fire barrier, fixing bracket, tap-off boxes with
circuit breakers, elbows, tee, feed unit, end cover, expansion unit, etc. shall
be from the same manufacturer. All the joint & contact surface shall be
silver plated.
The components of BBT shall be appropriately as follows but the
bidder must inspect the site and supply everything to complete total system.
BBT-1 :
1600A Distribution Board Connection Unit : 1
No.
1600A Bends : 2 Nos.
1600A Transformer connection unit : 1 No.
1600A Straight length : 5.00 meter (approx.)
Fire Barrier : 1 Lot.
Hanger : 1 Lot.
BBT-2 :
1600A Distribution Board Connection Unit : 1
No.
1600A Bends : 4 Nos.
1600A Straight length : 40.00 meter ( approx.)
Fire Barrier : 1 Lot.
Hanger/floor support : 1 Lot.
Tap-off boxes with 200A TP
(50KA) MCCB : 7
Nos.
Tap-off boxes with 160A TP
(50KA) MCCB : 1
No.
End Cap : 1 No.
BBT-3 :
600A Distribution Board Connection Unit : 1
No.
600A Bends : 4 Nos.
600A Straight length : 43.60 meter (approx.)
Fire Barrier : 1 Lot.
Hanger/floor support : 1 Lot.
Tap-off boxes with 160A TP
(50KA) MCCB : 1
No.
Tap-off boxes with 63A TP
(50KA) MCCB : 7 Nos.
500A End Cap : 1 No.
INSTALLATION:
The BBT system shall be fixed on floor
ceiling and walls with all necessary, cutting and breaking, cleaning and
mending the same including cement/sand plastering and painting clamps, nuts,
bolts as per the installation drawing of the manufacturer after getting
approval from the Owner / Consultants. The contractor shall supply all
materials required for complete installation of the BBT system.
INSTALLATION:
H.T. SWITCHGEAR
& METERING PANEL:
All standard checks of the equipment before installation
shall be done by the Contractor and unit shall be installed and tested as per
direction of the manufacturer and Consulting Engineer. Required finishing work
shall be done by the Contractor and hooking up the unit with the system shall
also be within this contract. Consumable materials required for complete
installation of the equipment including cables compound, boxes etc. shall be
supplied by the Contractor. After complete installation be unit shall be tested
by the Contractor upto the satisfaction of the Consultant and the
Engineer-in-charge.
All accessories shall be installed as per
direction of the Manufacturer and the Consultants. If the equipment is damaged
during handling and installation. The Contractor must repair the damage or
replace the damaged parts at his own cost,
TRANSFORMER:
The Transformer equipments
should be checked
before installation by
the Contractor and installed and tested as per direction of
the Manufacturer and Consulting
Engineers and Engineer-in-charge / Consultant.
Required finishing work shall be done by the
Contractor and hooking up the transformer with the system shall also be within
this contract. Consumable materials required for complete installation
including cable compound boxes etc. shall be supplied by the Contractor and the
rate quoted shall be inclusive of all incidental expenses. Care should be taken
during carrying the transformer and its
related parts. if there is any damage during handling and installation the
Contractor will be liable to replace the damaged parts at his own expenses.
After complete installation the transformer must be tested and commissioning as
per direction of the Engineer-in-charge / Consultant, Manufacturer and
Consultant.
L.T. SWITCHGEAR:
All L.T. Gear equipment must be installed on
proper foundation. All consumables required for the complete work shall be
supplied by the Contractor. The work shall be complete with all internal
electrical connections. After complete installation of the panel the Contractor
should test the complete L.T. Gear equipment as per manufacturer specification
and direction for full satisfaction of the Consultant and Engineer-in-charge.
CAPACITOR:
The item includes supervision of installation
of capacitor on prepared foundation. The foundation is to be prepared by Contractor as per direction of the
Engineer-in-charge / Consultant. All consumables required to install the
equipment shall be supplied by the Contractor. After completion of the
installation the Contractor should test the equipment in presence of Consultant
to his satisfaction.
EARTHING
SYSTEM:
The work under this item shall consist of
supply and installation of earth electrode
with copper lead, earthing inspection pit and connecting to the
specified terminal according to the drawing, specification and direction of the
Engineer-in-charge / Consultant. The whole electrical system including light,
fan, regulator sockets sub-station and metal parts incorporated with building
electrification shall be earthed.
The earth resistance of the electrodes system
shall be to the satisfaction of the local supply authority and shall not exceed
in one ohms.
Materials
:
Earth
Electrode :
The earth Electrode in a 1 and 1/2” dia, G.I.
pipe with 3/16th inch. dia drilled holes.
The G.I. pipe shall be similar to the
specification.
The pipe earth electrode shall be sunk and
buried below ground level upto its full length or as advise by the
Engineer-in-charge / Consultant. The earth lead and be connected to the earth
electrode by brass/G.I. clamp. After
making connection the clamp shall be covered with bitumen poured hot and with
jute cloths.
Earth lead
:
Earth lead shall consist of two numbers, 2
SWG high conductive electrolytic bare copper wire meeting the requirement of
B.S.S. 6360 : 1969 and/or it’s equivalent.
All earth lead shall follow the shortest and
most direct route to the earth electrode avoiding sharp bend and from
inspection pit to the entry at the building shall be enclosed in 1” dia G.I.
pipe. The earth lead shall be connected to test earth electrodes by means of
lugs, bolts, nuts and double washers to fixed as to make permanent and positive
connections both electrically and mechanically. The joints shall be covered
with PVC compound without disrupting the continuity.
Earth Inspection Pit :
Inspection pit shall have to be constructed
over earth electrode to inspect and test the connection terminals. bricks used
shall be of Ist class and only approved quality cement shall be used, Jhama
brick khoa for R.C.C. cover shall be 3/4th inch down graded and washed, cleaned
before casting. 3/8th inch dia M.S. Rods @ 4” c/c with two 1/2” dia M.S.
Hook shall be provided in the cover
slab.
Installation :
Electrode
:
The pipe earth electrode shall be sunk and
buried below ground level upto its full length or as devised by the
Engineer-in-charge / Consultant. The earth leads shall be connected to the
earth electrode by silicon aluminum bronze body clamp and phosphor bronze
screws. After making connection the clamp shall be covered with bitumen poured
hot and with jute cloth.
Lead :All earth
lead shall follow the shortest an most direct route to the earth electrode
avoiding sharp bend and from inspection pit to the earth electrode avoiding
sharp bend and from inspection pit to the entry at the building shall be enclosed
in 1” dia water grade PVC pipe. The earth lead shall be connected test earth
electrodes by means of lugs, bolts, nuts and double washers of failed as to
make permanent and positive connections both electrically and mechanically. The
joints shall be covered with PVC compound without disrupting the continuity.
Pit :
Ist class brick made inspection pit and RCC
cover with Sub-Station & Diesel Generator Set Set hook shall be built on earth electrode as
described here above at the location shown on the drawings the electrode shall
be within 10’-0 from the building.
Maximum Earth Loop
Resistance :
The maximum earth loop resistance any point
in the installation including earth lead to the earth electrodes shall not
exceed the resistance specified in the schedule or that indicated by the
Consultant. The contractor must ensure that the leads are efficiently bonded to
all metal work other than the current carrying parts. So that the above
resistance level is not exceeded. It will be the duty of the contractor to provide
earth tester, test the installation in presence of the authorized
representative of the authority and submit earth test report to the authority
for approval.
Method of Measurement :
Measurement shall be per set of earthing system installed.
GENERATOR
:
ITEM :
DIESEL ENGINE Driven A.C. generator set
having a prime power output as per schedule (continuous rating) standard
voltage 230/415 volts, 3-phase, 50Hz, 4-wire at 1500 rpm under condition of
normal temperatures and pressures. The manufacturer must have ISO9001.
GENERAL
DESCRIPTION:
The engine and alternator assembly shall be
directly flanged coupled, the alternator being driven by a flexible coupling
connecting engine fly wheel to alternator rotor.
The unit should be mounted together with
cooling radiator on a fabricated, heavy steel frame of all welded construction
designed to accurately align and support the assembly. The base frame is to be
predrilled to allow for ant vibration mounts and is to be provided with special
Sub-Station & Diesel Generator Set Setting arrangement for case of handling
and safety purposes.
There must be arrangement for manual/
automatic battery electric start being operated from the main control panel
which shall also include all monitoring and protection devices covering the
mechanical and electrical systems.
DETAILED
SPECIFICATION:
Diesel engine driven generating set having a
continuous rated output at 0.8 Power factor at 415/230 Volts, 3-phase, 4-wire,
50Hz at 1500 RPM under conditions of normal temperatures and pressures with 10%
overload for one hour at conditions specified under B.S. 5514, DIN6271, ISO
3046/1.
ENGINE:
The engine shall be of 6 cylinders, 4 stroke,
Air to Air after cooled, turbocharged, pressure lubricated, direct injection,
water cooled, industrial type Diesel engine developing the rated bhp at 1500
RPM, at NTP conditions.
The engine shall be complete with close
control governing to BS 5514, 1979 Class A1 Fuel Injection equipment with :
a) Fuel
oil filters
b) Lubricating
oil filters
c) Air
cleaners/filters
d) Fuel
solenoid energized to run,
e) Lubricating
oil pressure pump,
f) Water
circulating pump,
g) Battery
charging generator,
h) Precision
mechanical governor,
i) Starter
motor,
j)
Fuel solenoid
k) Thermostatically
controlled by pass system
ENGINE STARTING:
The engine shall be fitted with manual
automatic electric starting by means of a starter motor arranged to engage with
the fly wheel.
ENGINE COOLING:
The diesel engine shall be cooled via a
tropical air blast heavy duty radiator
with engine driven pusher type
fan, complete with water circulating pump, radiator guard, thermostat and by
pass system.
BATTERIES:
The unit shall be supplied with a set of suitably rated heavy duty
12/24 volt industrial type lead acid batteries (dry charged). A mains operated
battery charger should be mounted in control cubicle.A set of starter cables
and connections would be supplied loose.
LUBRICATING
SYSTEM:
Wet sump force feed lubrication system by
gear driven oil pump incorporating replaceable oil filters.
EXHAUST
SYSTEM :
The engine
shall be supplied with: Acoustic type silencers, flexible bellows
sections and rigid exhaust pipe of suitable length, suitable for use with Vee
form engine, supplied loose for site erection. The complete exhaust system
shall be designed to prevent any de-rate of the engine due to excessive back
pressure. All exhaust components are to be finished with heat resistant paint.
ALTERNATOR
:
Brushless Salient pole rotating field,
self-exciting, self-regulating, single bearing construction with integral
automatic voltage regulator providing voltage control to within +/- 2% of
nominal range, no load to full load and at all power factors between unity and
0.8 lagging and with a maximum 5% prime mover speed variation.
Class H insulating on both rotor and stator
windings and with enclosures to IP21 of BS 4999 Part 20, IEC & DIN
standards. The alternator meets the requirement of BS 5000 and radio
suppression to BS 800 & VDE class G&N.
ANTI-VIBRATION
MOUNTINGS:
A set of anti-vibration mounts and spring
isolator would be supplied loose for positioning beneath bed frame when the
side is delivered to site. These have their own in - built leveling device and friction pad, therefore fixing to the
floor is not necessary.
FUEL
SYSTEM:
The unit shall be supplied with a base
mounted fuel tank in corporate in the base frame of the unit providing
sufficient fuel for 8 hours continuous full load operation, the base shall be pressure tested prior to
assembly and will incorporation dial type
content/gauge, filler cap, vent
pipe, drain cock and all necessary fuel connections. All pipe terminations
shall be completed during works assembly. The system shall include arrangement
for low and high level alarm system of fuel. An additional daily fuel tank
(self Standing) of 1500 liter capacity with automatic supply type including
level switch & pump.
FUEL
TRANSFER:
A set of rotary type hand pump would be
supplied with 3 meters of flexible pipe, suitable for manual fuel transfer to
the daily service fuel tank.
COUPLING:
The alternator casing would be flange mounted
to the engine flywheel housing and the rotor shaft, coupled to the engine
flywheel through a flexible element to minimise torsional vibration throughout
the operating range.
BASE
FRAME:
The engine and alternator would be mounted on
a fabricated steel type base frame of welded construction adequately designed
to resist bending and torsional forces. The base frame shall accurately align
and support the assembly and shall provide Sub-Station & Diesel Generator
Set Setting points and location points for securing to the foundation.
SWITCHGEAR:
Switchgear and instrumentation shall be
mounted in totally enclosed, stove enameled sheet steel, set mounted control
panel fixed to the saddle frame of the alternator by means of rubber
anti-vibration mounts. The panel shall have provision for BBT connection. The control panel would have access to all
internal components and include the following:
1- OFF/MANUAL/AUTO
selector switch.
1- Frequency
Meter.
1- Volt
meter (0-500V) with selector switch (six positions)
3- Ammeters
(0-1000A) with selector switch.
1- 1000A
TP circuit breaker with adjustable thermal and adjustable magnetic trips.
1- Battery
charger indicator with ammeter.
1- Key
start switch
1- Hour
run recorder
1- Set
of relays and timers
1- Set
of cartridge type fuse
1- Set
of output terminals
1- Set of indicator lamps for fault indication of Low Oil
pressure, High Engine Temperature Gauge, over speed, Overload and reverse Power
relay, over crank.
1- Fault protection reset switch and 1- buzzer to draw
attention.
The Control Panel would be complete with all
internal wiring cables and accessories necessary for satisfactory operation and
maintenance. The control system should be manually reset once the fault is
rectified. All the failure circuits must incorporate a “Press to Test” facility
which when operated will remove the fault and shut the generating plant down.
ENGINE
INSTRUMENTATION:
Incorporated in the control panel or mounted
on a separate engine mounted panel, our option, shall be the following engine
instrumentation:-
1- Oil
Pressure gauge.
1- Water
Temperature gauge.
1- Hours
run recorder.
BONNET
& SOUND PROOF CANOPY:
Should be fabricated by heavy duty steel
structure covering with steel sheet. The inner side of the steel enclosure
should be lined with sound absorbing materials which should be covered by
perforated steel sheet. The sound reducing level should be 82 dBA @ 1 meter
from the canopy.
GENERATING
SET PROTECTION:
The unit shall be arranged to automatically
shutdown and indicate the same in the event of:
Fail to start
Low oil pressure
High engine temperature
Engine over speed
Overload
Over/under voltage protection
FINISH:
The generating set would be finished in
Hammer blue/Yellow and the control panel in grey/Yellow.
HAND
BOOKS:
ii. Engine & alternator parts catalogue.
TOOLS:
One set of standard routine maintenance tools
would be supplied in a tool box.
AUTO
CHANGE OVER SWITCH:
At the event of mains failure, an energy stop
switch should be attached with the Alternator body, the generator shall start
or if supply voltage goes below specific level or single phasing automatically
and change over to the load. With restoration of main supply the generator
shall shunt down automatically as well as the load shall be transferred to the
normal supply. The bidder must mention the change over time in seconds.
The supply and installation of generators
with automatic change over switch shall be on “turnkey basis” and shall include
the cost of:
a) Taking
necessary permission from the relevant of authority.
b) All
pipe works.
c) all
inter connecting power and control cable works.
d) Daily
and reserve fuel tank including the transfer pump.
Source PWD Schedule Book2014
Substations are normally outdoors and are enclosed by a wire fence. However in residential or high density areas, the substation may be indoors and housed inside a building to restrict the humming noise of the huge transformers.
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