Supply, installation, testing and commissioning of 250kVA, 415V, 50Hz, DG-Set
with weather proof acoustic enclosure, AMF panel, LT distribution switch gear panel for
providing stand-by source of power supply.
Detailed specification for Diesel engine and Generator set
Diesel Engine
The diesel should be vertical cylinder type having 6 cylinders totally enclosed, compression
ignition, water cooled (radiator cooled), turbo charged cooled suitable for Power generation
application having minimum of 306 BHP capacity to drive the 250 kVA alternator at 1500
rpm under NTP condition confirming to BS 649, complete with all interconnecting piping
and the following standard accessories.
a) Suitable fly wheel.
b) Flexible coupling
c) Air cleaner
d) Radiator – heavy duty type
e) Cooling fan
f) Water circulating pump
g) Corrosion resistor
h) PT fuel pump
i) Electronic governing control (EGC)
j) Fuel filter
k) Fuel shut down solenoid (24Vdc, stop solenoid)
l) Lubricating oil filter
m) Oil cooler
n) By pass filter
o) Silencer (Residential type)
p) Starter
q) Engine instrument panel with following
ƒ Lubricating oil temperature
ƒ Lubricating oil pressure gauge
ƒ Water temperature gauge
ƒ Hour meter and speedometer
r) The engine should have following
ƒ Safety control trip for low lube oil pressure
ƒ Safety control trip for high lube oil temp.
ƒ Safety control trip for high water temp.
ƒ Safety control trip for engine over speed
Page No. of 9 2
Requirement for the diesel engine
The diesel engine shall be vertical cylinder, single acting, mechanical injection type
and furnished with all the required equipments as per standard practice. The engine should
develop rated horse power to drive 250kVA alternator.
The required auxiliaries, guarantee of fuel consumption for rated output, provision for
parallel operation, governor performance and torsional vibration shall be in accordance with
BS : 649.
The engine shall be provided with an exhaust gas turbo charger and a charged air
cooler, integral air intake filter and silencer.
The engine should have throttle control, the engine water cooling should have
radiator. For charged air cooler, the cooling water inlet flow shall be thermostatically
Fuel system
Fuel (Diesel) system to the engine shall be supplied from a fuel tank. The supplier
should provide a fuel tank of 900 liter capacity, including 200 liter reserve capacity to be
installed in a weather proof enclosure. The supplier should provide mechanical fuel level
indicator with ‘Low’ and ‘High’ markings. Also fuel level indication should be provided in
the AMF panel with alarm for Fuel level ‘low’( if fuel level falls below 200ltrs.)
The fuel tank shall be free standing, floor mounting type with mounting brackets, fuel
inlet and outlet, air vent , drain plug, opening with cover for direct filling from the top of the
tank. Provide suitable fuel pipe lines for suction and return with bends, collars etc.
An engine driven booster pump shall be provided to deliver fuel from the supply line
to the fuel injector through two numbers of fuel filters.
Lube oil system
The automatic pressure lubrication shall be provided by an engine driven pump. This
system should be complete with an oil cooler and 2Nos. of 100% capacity mesh filters. The
oil cooler should be water cooled and equipped with necessary bypass arrangement, to
bypass cooler during starting until oil temperature reaches the minimum (or the threshold)
Engine starting system
Starting of the diesel engine shall be of electric starting . The electric starting system
should have starter motor, Lead acid starter Batteries, battery charger and necessary
instrument and accessories to indicate the condition of the batteries.

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The batteries shall be sized taking in to account the starting load requirement of the
D-G set. 2Nos. of 12V, Lead acid batteries, of suitable capacity to start the engine by 24V
DC electrical starting Motor without struggling, and with suitable capacity of battery cable.
The batteries must be capable to try 3 unsuccessful starts continuously. The batteries have to
be placed on a suitable well painted steel stand.
Air intake system: Air intake system should have requisite air filters and complete
interconnecting piping, supports etc..

Exhaust system
Engine exhaust system shall consist of exhaust gas driven turbo charger with lagged
piping, interconnecting cylinder head out lets with the turbo charger inlet. Exhaust gas from
the turbo charger shall be let out through exhaust gas silencer. The exhaust gas silencer,
necessary pipes etc., shall be provided by the contractor. Exhaust piping shall be suitably
cladded with aluminium sheets, mineral wool etc. The silencer should be of residential type.
Flexible connection (expansion joints) shall be provided in the exhaust piping to
avoid transmission of vibration from engine to the structure (acoustic and weather proof
enclosure etc.). Also the exhaust line with suitable bends, collars, flanges, angle supports and
other accessories should be provided. Provide necessary arrangements to avoid entry of rain
water, falling dust etc. at the top of the exhaust pipe. The exhaust piping system should be
designed and laid upto a height of 5 Meters above the acoustic enclosure or as directed by the
NAL authorities to suit the site and environmental condition as per the controller pollution
board , standards.
Engine governing system : The engine governing system shall be of class ‘A’ hydraulic
governor. An over speed trip mechanism shall be provided to automatically shut off the fuel
supply incase of set speed reading about 110% of rated speed.

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The Alternator
The Alternator shall be screen protected, drip proof, separately excited system
(with PMG) of brush less, continuously rated to give an out put of 200kW/250kVA at 0.8 pf
at 415V, 50Hz, 1500rpm,3 phase, 4wire. The alternator should be provided with automatic
voltage regulator with voltage regulation of ± 0.5% (MX321) and is designed, tested for
confirming to IS 4772/1992 or IEC 34.
Requirement of alternator
a) kVA rating : 250
b) kW rating : 200
c) Terminal voltage :415V
d) Power factor : 0.8 (lag)
e) No. of phases : 3
f) No. of wires : 4
g) Type of excitation : with built in PMG
h) Voltage regulation : ± 0.5%
i) Frequency : 50Hz
The insulating material of the alternator shall be non-hygroscopic and fully
tropicalisesd. The Alternator shall be suitable for operation with its neutral solidly grounded.
The neutral shall be formed at the terminal box.
The alternator terminal box is made out of 16 SWG sheet steel having louvers and
removable type bottom gland plate, top inspection cover and 600A capacity tinned Copper
Bus-bars for all phases and Neutral. The Bus-bar should be properly supported with
porcelain / resin cast epoxy molded bus supports. Provide sufficient clearances between
phases and earth as per BS / IS standards.
Mounting : Design, fabricate suitable base frame, which is a welded construction using
channel iron etc. to mount D-Gset. The whole set and base frame should be mounted on 12
Nos. (min) of heavy duty type Anti vibration mounts of ‘DUNLOP’ (b – SERIES)
or its equivalent make.

Page No. of 9 5
AMF control panel
The automatic mains failure (AMF) panel should be made out of well painted 16SWG sheet
steel enclosure with necessary components like mains contactor, control relays, timers, busbars,
protective relays, metering , battery charger, indication annunciation system etc should
be provided.
a) The panel shall be floor mounting, cubical type, indoor, dust and worm in
proof, totally enclosed, made out of 16SWG sheet steel, having hinged
door with removable type bottom gland plates. Bottom frame for concrete
floor mounting
b) Bus-bar should be of 600A capacity tinned copper for all the phases and
Neutral with color coded heat shrinkable sleeves. Sufficient capacity of
earth bus should be provided on either side of the panel.
c) The AMF should be operate in Test/ manual / auto mode and 3 attempt
starting facility with necessary control relays.
Requirements in AMF panel
ƒ Four pole Air break contactor for Mains and for Alternator of 630A capacity
ƒ Three over current relay for generator protection (CDV61/62)
ƒ Instantaneous earth fault Rely through Neutral CT (1A-4A)
ƒ Field failure relay YCGF-11A
ƒ HRC fuses for short circuit protection on both mains and for alternator.
ƒ Mode selector switch ( Auto / Manual / test / off
ƒ Voltmeter with selector switch 0 – 500V A.C. Analog type
ƒ Ammeter with selector switch 0 – 400A, A.C. Analog type
ƒ Line voltage monitor (3phase) with adjustment for presetting the voltage
ƒ Current transformers 400/5A 5P10 for protection and class1 for measuring
Note: The line voltage monitor (LVM) should monitor the voltage condition of
the mains supply and bring the D-G set in to operation if the line voltage falls
below ±10% from the rated voltage of 415V.

ƒ kWh meter ( energy meter) 3Phase, 4wire unbalanced type
ƒ Suitable capacity of current transformer for Measuring and protection of
15VA class 1 (metering) & 15VA 5P10 for protection
ƒ Power factor and frequency meter
ƒ Built in battery charger with DC voltmeter, DC ammeter selector switch
for trickle and boost charge
ƒ Frequency monitor
Apart from the above the panel should have necessary DC/AC aux. relays,
control fuses, MCBs, pushbuttons for start, stop, accept, reset, test,
emergency, indication lamps for healthy, trip, faulty indication, fuel level
low,24Vdc alarm with all indication for various faults. Use minimum of
2.5sq.mm copper wire for control circuit
Page No. of 9 6

Note : The AMF Panel should be erected at LT switch gear room as directed by NAL
authorities. Six sets of as made drawings should be submitted
Provide a suitable reinforced cement concrete Pedestal for both the D-G set and fuel tank
with concrete proportion of 1:2:4 and reinforcing steel rods of 12mm dia .. RCC bed should
rise at least 0.3m above the ground level.
The Generator Neutral should be earthed with 2Nos. of Copper plate earthing as per
BS 6043
Supplier shall perform all standard tests (Shop tests) on Engine and alternator and the
test reports pertaining to the engine and alternator should be submitted.

Supplier shall perform the following tests at site to the satisfaction of NAL
a) Testing the set in Auto / Manual / Test modes.
b) Testing for all Interlocks
c) Full load test on the set for Eight hours
Note: It is the responsibility of contractor to arrange the Necessary load, fuel, lube oil,
tools and test equipment required to carry out the tests at the site without any additional