19th June to 22nd June 2015

Rajdhani Express

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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 phase AC. 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

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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

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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.ReactorInter Vehicular coupling (known as Z-S coupler ) between coaches.TransformersDisconnecting and Earthing DeviceBattery 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

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alternator shaft for electrical power generation. Each engine produces 496 BHP of mechanical energy.

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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.

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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 present in 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.

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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

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maintenance the coupling is connected to the dummy 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 boost mode (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.

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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.

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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.

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60 KVA. Transformer under the coach 60 KVA. Transformer in the Power Car

Water Pumps: The 750V AC coming from the alternators is stepped down to 3 phase 415V 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. One of 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.

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Water Pumps set under the coach

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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 bedroomsAC 2 tire with open berth with curtains for privacyAC 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.First AC 1 H1AC Two Tire 3 A1 – A3AC Three Tire 12 B1 – B12Pantry Car 2 PCGenerator 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

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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

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First Class AC coach:

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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 storage selection for food and water. For this purpose 2 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.

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Equipment Description

Load (Watt)

Quantity Total load (Watt)

Deep Freezer, 230ltr 400 1 400Bottle cooler 90ltr 200 1 200Hot case 140 meals 1600 1 1600Insect killers 20 2 40Oven toaster Grill 1200 1 1200Water boiler1 2000/3000 1 2000/3000Water boiler2 2000/3000 1 2000/3000Water boiler1 2000/3000 1 2000/3000Electric burner 1 2000 2 4000Electric burner 2 2000 1 2000Electric burner 3 2000 1 2000Electric burner 4 2000 1 2000Refrigerator, 310 ltr 300 1 300Electric chimney 1 300 1 300Electric chimney 2 300 1 300Electric chimney 3 300 1 300Total load (watt) with 2000 Watt water boiler 28540Total load (watt) with 3000 Watt water 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

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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

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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.

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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 refrigerant gas 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(maximum 180 psi). The compression 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 constant pressure , 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.

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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 refrigerant liquid to expand to a lower pressure corresponding 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

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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 pressure drops down below 10 psi gauge. It protects 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 containingSilica 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:

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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-out to shut down 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 pressure switch 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.

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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

Under Frame Hung

Weight 900 Kg 2700KgInstallation Time 4 Hrs 4 daysRefrigerant R-22

monochlorodia fluoro methane

R-134a tetra fluoro ethane

Charge Less than 3.0 kg 15- 20 kgSystem design Hermetically

sealedOpen

Roof leak potential

Nil Enormous

Power supply AC. NilDamage due to Cattle run

Nil Heavy

Damage due to flash floods

Nil Heavy

Performance Excellent Deteriorates quickly due to dust collection under coach

Technology Latest Old and obsoleteWater drop on Nil Passengers at

endFresh air From roof Takes from toiletCapacity control 25%-100% 50- 100%Down time for repairs

4 hrs Very long repair required

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