Vocational Training at Eastern Railway, Sealdah.

1. 19th
June to 22nd
June 2015
Rajdhani Express

2. 15 Rajdhani Express
Introduction: Rajdhani Express is a passenger train service, offered by the Indian
Railways, operating between New Delhi and other important destinations, especially
state capitals.
Rajdhani Express was introduced in 1969, for providing fast connections (up to
140 km/h or 87 mph, speed variation depending upon the particular track section)
from New Delhi to the capital cities of various states in India. The first Rajdhani
Express left New Delhi station for Howrah station to cover a distance of 1,445 km in
17 hours 20 minutes.
This superfast train service get highest priority on the Indian railway network. They
are fully air-conditioned. Passengers are served complimentary meals during the
journey. Depending on the duration and timings of the journey, these could include
Morning Tea, breakfast, lunch, high tea, and dinner.
Presently the technology used in these trains has been obtained from Germany, with
each individual coach built and exported by LINKE-HOFMAN & BUSCH (known as the
LHB coaches).The newest coaches are said to be manufactured by a German
company ALSTOM.
This superfast train service runs on electric locomotives drawing power from
overhead 25 kV lines with the help of Pantographs. However power required for
lighting, heating, air conditioning purposes is generated using Diesel Generator
sets(known as D.G sets), implementing EOG(End on Generation) with two power
cars at the two ends of the train.
All Rajdhani Express trains offer three classes of accommodation: AC First Class with
2- or 4-berth lockable bedrooms, AC 2-tier with open berths (bays of 4 berths + 2
berths on the other side of the corridor) with curtains for privacy, and AC 3-tier (bays
of 6 berths + 2 berths on the side) with curtains for privacy (according to recent
directive the curtains in all 3 tier accommodations have been removed).
 Power scheme in Rajdhani Express: The entire power required for AC.
system,
lighting system, Pantry Car power is
delivered by the DG sets established in the Power Car. The DG. sets produce
750 V. 3 phaseAC. power for low transmission loss. The 750 V. AC. power then
dropped down to 415 V. 3 phase AC. power by two 60 KVA. transformers for
two DG sets. This 415 V. AC. power go to metering and control section.
According to original German designing the generated 750 V. AC. power go to

3. 16 Rajdhani Express
two 60 KVA. transformer by two feeders from two DG sets. Then the voltage is
dropped down to 415 V. and transmitted to the Roof Extractor sets and
Radiator Motor sets by one branch from each transformer secondary and
another two branches of the two transformers joined together and then
supplies power to the other loads. According to the RCF designing there are
two 60 KVA. step down transformers, connected with the 750 V. generated by
the two alternators by primary side and the secondary of the transformers
carrying 415 V. AC. are connected to the Roof Extractor sets and Radiator
Motor sets. Other branches from the DG sets carrying 750 V. AC are joined
together and then they are connected to a 60 KVA. transformer. The output of
this transformer, 415 V AC. then transmitted to the other loads. Now the 415
V. three phase AC. supply is directly connected to the RBC, EBC, AC Plant,
Exhaust Fan and Water Pumps. A phase to neutral, 220 V. from this 415 V.
three phase supply is connected to a 1 KVA. transformer (Lighting Transformer)
and through a 220 V. single phase AC. to 24 V DC. converter the starting
batteries the Self Starter sets (through a Starter Motor Isolating Switch) are
connected to the 415 V supply. The RBC converts the 415 V. AC. to 110 V. DC.
and is connected to a 110 V. 70 AH. Battery set by one branch of it’s output.
The another branch of it’s output and the output of EBC is connected together
which supplies 110 V. DC. to Anti Skid Device, Light Controlling Device,
Emergency Lights, MVR. , Back Light, Air Conditioning system etc. This 110 V.
DC. is connected to a 110 V. DC. to 24 V. DC. converter. The output of this
converter, 24 V. DC. supplies Sanitary Control System, Fire Control Circuit, Fire
Sensors, Loud Speakers and UIC Remote Control. The output of the Lighting
Transformer supplies 110 V. AC. to the lights and the Electric Razors.
The power scheme of the AC Hot Buffet Car (Pantry Car) is different. There are
two Feeder from the two DG sets carrying 750 V. AC. power which supplies
power to the coaches and to the Pantry Car. Two 60 KVA. transformers are
connected to the two feeders separately. There are two Insulation Control
240/ 415 V. Transformers, connected to secondaries of the two 60 KVA.
transformers. The local main of 415 V. AC. is connected by switch to the
secondary of 60 KVA. transformer (T – 1 which is connected to feeder 1). The
415 V. three phase bus bar coming from the T – 1 is directly connected to the
RBC, EBC and to the two Water Pumps. The single phase 220 V. supply from
this 415 V. bus bar is connected to the AC Unit 1, Exhaust Fan, Electric Burner
3, Water Filter, Electric Chimney 1 and 2, Electric Burner 1 which are two in
number, Cold Dispensers, two OTGs. The one branch of RBC (Supplies 110 V.
DC. from 415 V. AC.) is connected to the 110 V. and 70 AH. Battery set. The

4. 17 Rajdhani Express
another branch of the RBC is connected to the output of the EBC and this
supplies 110 V. DC. to the Pump Control (in new coach), Anti Skid Device, Light
Control, Emergency Light, AC Unit etc. From this 110 V. DC. a 110 V. DC. to 24
V. DC. Converter is connected and it supplies pump control (in old coach),
Sanitary, Loud Speakers and UIC Control. The 60 KVA. transformer (T – 2)
connected with the feeder 2 supplies 415 V. three phase AC. to the bus bar 2.
This supplies Electric Chimney 2, Insect Killer, AC Unit 2, Hot Dispenser, Electric
Burner 4, Electric Burner 2, Fridge etc. There are two connections from two
415 V. bus bars (Bus Bar 1 and Bus Bar 2) connected by a switch with a 1 KVA.
(220/ 110 V. AC.) transformer. The secondary of this transformer supplies the
lights and Electric Razors. The Schematic diagram of the Power Scheme is
depicted under Pantry Car article.
The components used in the power supply system in Rajdhani Express,
Diesel Generator (DG ) set (2 in each power car ) comprising diesel generator
and an alternator coupled together.
Reactor
Inter Vehicular coupling (known as Z-S coupler ) between coaches.
Transformers
Disconnecting and Earthing Device
Battery Box
 DG set coupled with alternator in Power Car or Generator Car: Each
Power car has two diesel engines coupled with alternators for power
generation. Each alternator produce 750 V ac supply ,with a capacity to
provide approx. 385 ampere current .Each coach requires about 40 ampere
current .Generally the efficiency is around 80% so about 300 amperes can be
used .
 Diesel Engine: The Diesel engines are manufactured by Cotton-Greaves .The
engine provides the mechanical energy required to rotate the alternator shaft

5. 18 Rajdhani Express
for electrical power generation. Each engine produces 496 BHP of mechanical
energy.

6. 19 Rajdhani Express

7. 20 Rajdhani Express

8. 21 Rajdhani Express
 Alternator: The alternator is coupled with the diesel engine .Each power car
has two alternators. The alternator specifications are given bellow.
 Specifications of Alternator:
The voltage required for usage for the appliances in the coaches is 415 V. But the
alternator generates more voltage because there are transmission losses from the
power car to the coaches.
Maker KIRLOSKER
ELECTRIC CO. LTD
Frame 4AB355/7
KVA. A
EXTR. A.C.
R.P.M.
Volts 750V
AMPS. 385A
EXTN. 280V
EXTN. 1.5A
Frequency Hz.
Phase 3
P.F. 0.8
Connection Y
Cooling temperature 55 degree C.

9. 22 Rajdhani Express
DG set coupled with Alternator in the Power Car of Rajdhani Express
 Inductive Reactor: The power generated in an ideal alternator is totally
sinusoidal without any unwanted surges and other harmonics .Only the
primary harmonics presentin the signal. Among them the odd order harmonics
specially the 3rd
order harmonics can damage the electrical equipment
severely. The reactor is used to remove these unwanted signals and provide
pure sinusoidal signal.

10. 23 Rajdhani Express
 Reactor specifications :
Maker KERALA ELECTRICAL AND
ALLIED ENGG. CO. LTD.
Volts. 125 V.
Ampere 50 A.
Frequency
Phase 1
Insulation class CLASS H
Insulation level AC 3
Type of cooling AN
Max. temperature rise degree C.
Core and winding 60 kg.
Total weight 110 kg.
 Inter- vehicular coupling: The power generated at the power car alternator
is supplied to the coaches via inter- vehicular coupling or Z-S coupling.
The fixed transmission lines are not used in the supply system. Because if any
of the coaches is needed to be
removed for maintenance or
some other purpose then the
transmission line is to be cut,
which is not a good operation.
At the time of coach removal,
coupling is opened and the
coach is disconnected from the
supply. At the time of
maintenance the coupling is
connected to the dummy

11. 24 Rajdhani Express
connector at the coaches.
Inter vehicular - coupling
 Disconnecting and Earthing device: While maintenance all the live supplies
are to be removed and switched off. While starting the maintenance the
device disconnects all supplies and after the job completion the device
connects the coach to the supply.
Disconnecting and Earthing Device
 Battery box: Under each coach there is a battery box. This is used for back up
supply to the coaches. Each box supplies 110V DC. Each box contains 9
batteries and each battery supplies 12.2 V DC. The batteries are charged by
regulated battery chargers (RBC) in side of each coach. If somehow this unit
fails to charge the battery the Emergency Battery Charger (EBC) charges the
battery.
Operation of RBC and EBC :
Regulated battery charger can sense the battery condition whether it is to be
charged in the float mode (fully charged) or in boostmode (discharged below a
certain level). Thereby it chooses the charging voltage. RBC consists of a
rectifier and a step down chopper circuit. Rectifier unit converts 415V, 3 phase
50 Hz AC to 130V DC and step down chopper i.e. the DC to DC converter
converts 110V to 24V.

12. 25 Rajdhani Express
In float mode the battery set of LHB EOG coach gets charged with a voltage of
121.5V i.e. 13.5V per mono block and in boost mode it gets charged with
128.5V – 129V.
When RBC fails to operate Emergency Battery Charger starts to operate giving
a constant supply of 115V – 118V to the batteries.
When EBC also fails we can observe the backup time for other components
from MVR (Minimum Voltage Relay) fail to operate then the contact no. 8 gets
opened instantly, resulting in turning off the PA system and the Music system.
After next 30 minutes of the failure the contact no. 9 gets opened resulting in
turning off the water pump system.
After next 8 minutes of turning of the water pump system the contact no. 10
gets opened resulting turning off the lighting circuit.
Battery Box
 Transformer: The power generated in the alternator is 750V. This is much
higher than the required value. The Transformers are used to step down the
voltage level to 415V AC. The transformers are located under the coaches.

13. 26 Rajdhani Express
Under each coach there is one transformer to supply power (excluding pantry
cars which have three transformers for each coach).
Specification of 60 KVA. Transformer:
Maker Vimal Transformer Corporation
Input 750 V. AC.
Output V. AC
Capacity KVA.
Frequency 50 Hz.
Impendence <4 %
Line Amp. 46.2 A.
Output 83.2 A.
Weight <440 kg.
Vector connection Yy0
Vector type Primary : Star Secondary : Star
There is a 60 KVA. transformer in the Power Car to step down the produced 750 V. to
415 V. to run the blower fans.
There is a transformer under each coach which steps down the 230 V. (Phase to
neutral) to 110 V. AC. for the fluorescent lamps in the coaches.
There are again step down transformers which transforms 110 V. AC. to 12 V. AC.
Then the 12 V. AC. is converted to 12 V. DC. for charging the batteries.

14. 27 Rajdhani Express
60 KVA. Transformer under the coach 60 KVA. Transformer in the Power Car
 Water Pumps: The750V ACcoming fromthe alternators is stepped down to 3
phase415V AC by the 60 KVA transformer. This 415V AC drives two centrifugal
pumps located in a stainless steel casing at the under frame supply the water
to the tanks. Oneof the 415 V pumps is always kept running, while the other is
kept on standby for 4 hours maximum. After 4 hours a microcontroller
switches the operation to the other pump. These supply water in the coaches.

15. 28 Rajdhani Express
Water Pumps set under the coach

16. 29 Rajdhani Express
 The coach configuration of Sealdah- New Delhi Rajdhani Express:
Almost every Rajdhani Express offers three classes of accommodation,
First class AC with 2 or 4 berth lockable bedrooms
AC 2 tire with open berth with curtains for privacy
AC 3 tire with curtains for privacy
The Rajdhani Express contains 20 coaches in total. The coaches are as below,
Coach Number of coach Coach no.
FirstAC 1 H1
AC Two Tire 3 A1 – A3
AC Three Tire 12 B1 – B12
Pantry Car 2 PC
Generator Car 2 EOG
The coach configuration is given bellow,
 Rake/Coach Composition:
LOCO-EOG-H1-PC-A3-A2-A1-B12-B11-B10-B9-B8-B7-B6-B5-B4-B3-B2-B1-PC-EOG

17. 30 Rajdhani Express
 Linke - Hofmann - Busch Coaches: Linke Hofmann Busch (LHB) coaches are
the passenger compartments of Indian Railways that have been developed by
Linke-Hofmann-Busch of Germany (renamed Alstom LHB GmbH in 1998 after
the takeover by Alstom) and produced by Rail Coach Factory in Kapurthala,
India. The coaches are designed for an operating speed up to 160 km/h and
could go up to 200 km/h. However, they have been tested up to 180 km/h.
Their length of 23.54m and a width of 3.24m means a higher passenger
capacity, compared to conventional rakes. The tare weight of the AC chair car
was weighed as 39.5 Tons. They are considered to be "anti-telescopic", which
means they do not get turned over or flip in case of a collision (chiefly head-
on). These coaches are made of stainless steel and the interiors are made of
aluminium which make them lighter as compared to conventional rakes. Each
coach also has an "advanced pneumatic disc brake system" for efficient
braking at higher speeds, "modular interiors" that integrate lighting into ceiling
and luggage racks with wider windows. The improved suspension system of
LHB coaches ensures more riding comfort for the passengers compared to
conventional rakes. The air conditioning system of the LHB coaches is of higher
capacity compared to the older rakes and is controlled by a microprocessor
which is said to give passengers better comfort than the older coaches during
summer and winter seasons. They are relatively quieter as each coach can
produce a maximum noise level of 60 decibels while conventional coaches can
produce 100
decibels. Each
LHB coach costs
between Rs.
15 million to
20 million,
whereas the
power car which
houses a
generator costs
about 30 million.
LHB coach of Rajdhani Express

18. 31 Rajdhani Express

19. 32 Rajdhani Express
 First Class AC coach:
The train has only one first class AC coach.
This may contain 2 berths or 3 berths system.
The coach has controllable music system. The announcement and the music
volume can be regulated in the first class compartment.
The first class coach does not have any bottle cooler or freezer.
 AC Two Tire and Three Tire coach:
The train has 3 AC 2 tier and 10 AC 3 tier coaches.
Each coach gets its own power supply from the transformer below them.
The 3 tier (6+2 berth) and the 2 tier (4+2 berth) coaches have their own
controlling and safety units at the ends of the coaches.
Each coach is provided with music system and announcement system which is
controlled from the panels at the end.
Each coach has its own storageselection for food and water. For this purpose2
deep freezers, 2 bottle coolers and 2 hot cases are provided. This unit is
operated by the compressors and the blower motors of its own mounted
below this unit.
(i) (ii) (iii)
AC (i)First (ii)Two and (iii)Three Tire coach
 Pantry Car: The pantry car is the coach to supply food to the passengers and
the staff members. There are two pantry cars at the two ends of the train after
the power cars. The different components of the pantry car are given bellow.

20. 33 Rajdhani Express
Equipment
Description
Load
(Watt)
Quantity Total load (Watt)
Deep Freezer, 230ltr 400 1 400
Bottle cooler 90ltr 200 1 200
Hot case 140 meals 1600 1 1600
Insectkillers 20 2 40
Oven toaster Grill 1200 1 1200
Water boiler1 2000/3000 1 2000/3000
Water boiler2 2000/3000 1 2000/3000
Water boiler1 2000/3000 1 2000/3000
Electric burner 1 2000 2 4000
Electric burner 2 2000 1 2000
Electric burner 3 2000 1 2000
Electric burner 4 2000 1 2000
Refrigerator, 310 ltr 300 1 300
Electric chimney 1 300 1 300
Electric chimney 2 300 1 300
Electric chimney 3 300 1 300
Total load (watt) with 2000 Wattwater boiler 28540
Total load (watt) with 3000 Wattwater boiler 31540
Due to all these high rating equipments are housed in the pantry car, it
requires more electric supply than other coaches.
Due to the operation of the heater, water
boiler and other high loading elements
there are much more risk for fire hazards.
To deal with this problem the Smoke
Detector is kept mounted in the ceiling of
the car connected with alarm system. The
smoke detector has a simple thermostat
switch that automatically switches on the
alarm under critical conditions.
Smoke Detector and Alarm

21. 34 Rajdhani Express

22. 35 Rajdhani Express
 Various Pantry Car Equipments:
1. Deep Freezer 2. Bottle Cooler 3. Hot Case 4. Insect killer 5. Water Boiler
6. Refrigerator 7. Electric Burner 8. Electric Chimney
 Air Conditioning system:
 Principle of Operation of the AC System: The air-conditioning process
maintains a constant climatic condition by controlling temperature, humidity,
cleanliness, noise and air motion. The air-conditioning system includes both
refrigeration and heating.
The refrigerating system depends for its action of the following principles,
 Latent principle: Any substance in passing from the liquid to gaseous state
absorbs at constant temperature s specific quantum of heat known as the
latent heat of evaporation and gives up latent heat on passing from gaseous to
liquid state.
Application: Evaporator and Condenser.

23. 36 Rajdhani Express

24. 37 Rajdhani Express

25. 38 Rajdhani Express
 Expansion principle: When a gas expands without external heat exchange it
temperature falls and when it is compressed without external heat exchange
its temperature decreases.
The air-conditioning system adopted in air-conditioned coaches work on
mechanical compression system and consists of the following,
 Evaporator unit consisting of cooling coil(heat exchanger), heater and
motor-driven blower unit.
 Thermostatic expansion valve.
 Motor-driven compressor.
 Air cooled condenser (with cooling fan driven by motor)
 Liquid receiver and dehydrator.
 Refrigerant piping for conveying the refrigerant(R-134A).
 The Refrigeration Cycle: A typical refrigeration cycle in an air-conditioned
coach can be represented also in a pressure enthalpy diagram as in figure. The
refrigerantgas at low pressure(represented by point C) is compressed to point
D. The compression process elevates the pressure from 37 psi(maximum 46
psi) to 150 psi(maximum180 psi). Thecompression of the gas also heats up the
gas to a superheat condition. The gas at the compressor outlet is superheat
and latent heat are removed at constantpressure, the refrigerant reaching the
point A at the end of this part of the cycle. The line A-B represents the
expansion that takes place in the expansion valve while the line B-C represents
the refrigeration effect that is obtained in evaporator.
Apart from cooling, the air conditioning equipment is also required to provide
heating when the outside temperature varies from 400
C to 200
C .The cooling
and heating will nave be necessarily automatic by means of thermostatic
controls incorporated in the unit. RDSO specification also lays down that the
equipment shall admit fresh air at the rate of 0.35 metro cube per minute per
passenger in the non-smoking area and 0.7 meter cube per minute per
passenger in the case of compartments where smoking is permitted.

26. 39 Rajdhani Express
 Description of various components of Air -Conditioning System:
 Evaporator unit: The evaporator unit consists of a thermostatic expansion
valve, a heat exchanger, a resistance- heating unit and a centrifugal blower
driven by a motor. The function of the thermostatic expansion valve is to allow
the compressed refrigerantliquid to expand to a lower pressurecorresponding
to the load demand. The expanded refrigerant passes through a heat
exchanger; the heat in the air is transferred to the refrigerant causing the
cooling of the air and the evaporation of the refrigerant inside the tubes. The
cooled air is led through the ducting to the various compartments and diffused
by means of air diffusers. Fresh air is drawn through filters to eliminate dust
and is mixed with the return air in the plenum on the inlet side of the
evaporator. Similarly, the return air filters so that the dust contained air in the
return air is extracted. When the outside ambient is very low and when the
refrigeration is not required, the heater is switched on according to the setting
of thermostat.
 Expansion valve: The primary function of the expansion value is to control
the quantity of liquid refrigerant admitted into the cooling coils of the
evaporator.. The expansion valve admits more refrigerant when the air
conditioning load is high, and reduces it to the minimum when the load is
low.If the airconditioning load varies greatly the superheat may be set
between 101 O
F to 150O
F.
 Compressor: The refrigerants vapour drawn from the evaporator is
compressed by means of a multi cylinder reciprocating compressor. The work
done due to compression raises the temperature of the refrigerant vapour.
 Condenser: The condenser serves the function of extracting the heat
absorbed by the refrigerant vapour in the evaporator and the heat absorbed
during the compression process. The condenser consists of a heat exchanger,
which is force-cooled by means of two or three axial flow blower fans. The
refrigerant vapour is cooled at constant pressure by means of the air blown
over the finned tubes and liquefied. The refrigerant liquid leaving the
condenser is led into the liquid receiver from where it proceeds to the
expansion valve on the evaporator. The liquid receiver is a cylindrical container
which contains a reserve of the refrigerant liquid. A dehydrator and filter are

27. 40 Rajdhani Express
also provided to ensure that the refrigerant is free from moisture and dust
particles.
 High Pressure cut-out: The high pressure cut-out is essentially a safety
device against build up of excessive delivery pressure and protects the
compressor and piping system from damage. I t is a pressure operative switch
which switches off the compressor drive motor when the pressure exceeds a
preset valve.
 Low Pressure cut-out: This is also a pressure operated switch similar to the
high pressure cut-out switch, but is shuts down the compressor if the suction
pressuredrops down below 10 psigauge. Itprotects the system against unduly
low evaporator temperatures and formation of frost on the evaporator.
 Dehydrator and Filter: Water vapor or moisture will cause trouble in any
refrigeration system. The moisture may freeze and block the expansion valve
orifice, and. also cause corrosion in working parts. This is best achieved by
subjecting the system of vacuum for 2 or 3 days. The dehydrator is another
drying device containing
Silica gel or other similar drying agent inserted in the refrigerant load for
removing moisture from the refrigerant while in operation. It should be
provided atleast temperature when the installation is brought into operation
to remove any moisture in the piping system.
 Refrigeration piping: The refrigerant piping consist of the suction line(from
the evaporator outlet to the compressor inlet) and the discharge line(from the
compressor outlet to the condenser inlet), and liquid line(from the liquid
receiver to the inlet side of the expansion valve). Connections to the gauge
panel from the compressor delivery side(high pressure side), low pressure side
and from the compressor crankcase, the lubricating oil connections, are also
part of the piping system, only copper pipes are used for refrigerant piping.
 AC Control Panel: The control of the airconditiong system is achieved by
means of Air conditioning Control Panel.
 AC Control Panel Components and their functions:

28. 41 Rajdhani Express
 Evaporator Fan Motor Proving Relay: The prevents energisation of the
compressor motor and condenser motor or Heater till trio evaporator motor
(16) comes ’ON’ and blows air into the duct through the evaporator coil. This
relay works in conjunction with a “Vone Switch” provided in trio air circuit. If
the evaporator blower motor supply fails or the motor does not run, the
compressor motor and the condenser motors/Heater will get switched ‘OFF’ by
this relay.
 Low Voltage Relay: This will trip to stop the compressor motor and
condenser motors/heater, and prevent them from starting by cutting off the
supply to their control circuit if the voltage of the battery is below 100 and
reset when battery voltage rises to 102 V. The relay is provides with a build-in
time delay f 5 seconds, to avoid nuisance – tripping.
 Cooling Pilot Relay: Acts as an electrical link between the cooling
thermostats and the control circuit of the compressor and condenser. This is
energized by electronic triggering set off by heat thermostat.
 Heating Pilot Relay: Acts as an electrical link between the heating
thermostats and the control circuit of heater. This is energized by electronic
triggering set off by thermostats.
 Main Control Switch: This is the control switch for starting or shutting down
the plant. This has got provision to select blower only, LOW, MEDIUM and
HIGH temperature setting.
 Oil pressure Cut-out Switch: This protect the compressor against lubrication
failure either due to lesser oil oil pump failure or blocking of oil piping, and acts
in conjuction with thermal cut-outto shutdown the compressor only if the low
oil pressure persists.
 Low pressure cut out: A pressure switch to protect against working of
compressor with low suction pressure due to loss of Freon gas or other
reasons. This switch has been connected by means of copper piping to the
suction header of the compressor.
 High pressure cut out: A pressureswitch to shut down the compressor when
compressor discharge pressure is too high. The switch has been connected to
the compressor discharge header by means of copper piping.

29. 42 Rajdhani Express
 Pilot lights: These lights indicate respectively normalcy oh the mains , blower
fan motor, compressor motor, heater and normal voltage. Indications are now
by LEDs.
 Comparison of roof mounted A.C system with conventional under frame
Hung:
Basis of comparison Roof mounted AC
system
UnderFrameHung
Weight 900 Kg 2700Kg
Installation Time 4 Hrs 4 days
Refrigerant R-22 monochlorodia
fluoro methane
R-134a tetra fluoro
ethane
Charge Less than 3.0 kg 15- 20 kg
System design Hermetically sealed Open
Roof leak potential Nil Enormous
Power supply AC. Nil
Damagedue to Cattle
run
Nil Heavy
Damagedue to flash
floods
Nil Heavy
Performance Excellent Deterioratesquickly
due to dust collection
under coach
Technology Latest Old and obsolete
Water drop on Nil Passengers at end
Fresh air From roof Takes from toilet
Capacity control 25%-100% 50- 100%
Down time for repairs 4 hrs Verylong repair
required

30. 43 Rajdhani Express