Friday, January 9, 2015

Specifications of Substation equipment and Generating Set

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:
The equipment would be supplied with:          i. Operation & maintenance manual.
                                                                 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

1 comment:

  1. 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.
    Transformer Manufacturer in India

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