193205603 All About Diesel Loco

5/20/2018 193205603 All About Diesel Loco

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Layout & Special Features Of GT46MAC

1. Lay Out

1 2 3 6 7 21 8 9 10 11 12 13

19 14 5 1620 4 15 17 18

1. DRIVERS CAB 12. COOLING FANS2. #1 ELECTRICAL CONTROL CABINET 13. RADIATORS3. DYNAMIC BRAKE GRIDS & FANS 14. AC TRACTION MOTOR

4. #1 TCC 15. BATTERY BOX5. #2 TCC 16. FUEL TANK6. DUST BIN BLOWER 17. UNDER FRAME7. TRACTION MOTOR BLOWER 18. DRAFT GEAR8. EXHAUST MANIFOLD 19. COUPLER9. ENGINE 20. AIR BRAKE RACK10 EQUIPMENT RACK 21. TRACTION ALTERNATOR11 AIR COMPRESSOR

AC-AC locomotives hitherto manufactured by GM have been only for the

North American market which does not impose any major constraint on thelayout primarily because axle loads are in region of 30t are permitted onNorth American Railroads. Development of the layout for GT46MAC theaxle load for which is restricted to around 20.5 t , was therefore, a majorexercise in locomotive design.

The locomotive has been designed on the platform concept i.e. the layoutand the mounting of equipment is arranged in such a manner thatretrofitment of equipment developed in future on existing locomotives aswell as equipment changes/upgradation of the existing design of the

locomotive can be implemented without any major change in theunderframe, superstructure and even layout.


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2 GT46MAC is provided with the fol lowing special features-

710G3B fuel efficient engine isa low maintenance high fuel efficiencydiesel engine. The fuel efficiency of this locomotive is 11 % better than

the existing WDM2 locomotive. The engine has many modern features like:

Laser hardened cylinder liners,

Unit fuel injectors which eliminate the problematic HP tube

Inconel valves and Hydraulic valve adjuster

Durable crankcase and piston structure

AC-AC transmission has the following features / advantages -

High adhesion and Tractive effort Maintenance-free traction motors

No limitation of minimum continuous speed

High reliability and availability

Lower rolling resistance and higher energy efficiency

Computer Control, a 32 BIT computer control for locomotive controlshaving, following advanced features -

Trouble Shooting and Self -Diagnostics

Alpha Numeric display

Archive memory and Data logging

Radar based super series Wheel Slip/Slide Control system

High adhesion HTSC bogies, which have traction bar arrangement withunidirectional traction motors resulting in low maintenance, longer wheellife and higher adhesion.

Improved mechanical systems, the notable being -

microprocessor based engine cooling system

High lube oil sump capacity Self-cleaning inertial type primary filter

Efficient secondary air filtration

Improved Miscellaneous Electrical Systems, the notables being:

Wide range dynamic brakes effective down to near standstill

Maintenance-free roller suspension bearings having lower rollingresistance

Efficient filtration for electronic cabinet


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5. Locomotive Design

There have been significant changes in locomotive technology duringpast 10-15 years. Modern electric and diesel-electric locomotives havesophisticated control systems that allow precise control for power applicationto the rails. These locomotives, therefore, have the ability to significantly out-perform older technology locomotives. Introduction of AC-AC technologyensures that the locomotives are dispatched to gain the maximum benefit ofthe increased dispatchable adhesion.

The following mechanical principles and mathematical formulasthat govern locomotive power application need to be clearly defined:

5.1 Locomotive Horsepower

There are four different horsepower ratings on a locomotive:

5.1.1 Brake horsepower.

Brake horsepower is measured at the engine crankshaft and is a measureof the TOTAL horsepower available for conversion to electrical energy atthe main generator plus the power required for dr iving accessory loads.

5.1.2 Traction Horsepower

Traction horsepower = Brake horsepower - Accessory l oads

GT46MAC locomotive has the following accessory horsepowerdemands:

Auxiliary Generator.

Traction Motor/Main Generator Blower.

Air Compressor - mechanically driven by engine, but has a zerohorsepower load when unloaded and is disengaged. GT46MAChas a clutch which disengages when no compressed air isrequired.

Inertial Filter Blower Motor.

Radiator Cooling Fans - electrically driven by the companionalternator. GT46MAC utilises two speed-cooling fans to lessenthe horsepower demands for engine cooling when full cooling is notrequired.

AC Inverter Blowers - electrically driven by the companionalternator.


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Traction HP rating is the most commonly used rating when quotinglocomotive horsepower. When railroads dispatch loads on hp/ton basis,they in almost all cases use traction hp for calculations.

5.1.2 Net Traction Horsepower

Net Traction Horsepower = Traction Horsepower x Generator Efficiency

In case of GT46MAC locomotive, 0.94 is the efficiency of the main generator.

5.1.3 Rail Horsepower

Rail horsepower, the power delivered by the locomotive wheels at the rails,can be expressed by Rail Horsepower = Traction Horsepower xTransmission Efficiency

Transmission efficiencyis through:

Main Generator

Switch Gear

Cables

Traction Motors

Traction Motor Axle Gears.

Inverters

5.1.4 Draw Bar Horsepower

The power developed at the draw bar called Draw Bar Horsepower and is theactual horsepower used to pull a trailing load. It is the engine to generatorhorsepower minus electrical transmission losses minus horsepowernecessary to move the locomotive only.

Drawbar Horsepower =

{(Engine to Generator H.P. x Transmission Efficiency) - (Loco weight x locomotiveresistance x kmph)}

270 kg km per hour

Due to the fact that the formula includes "locomotive resistance" and kmph, itis necessary to specify the grade and curve condition as well as the speed ofmovement to obtain draw bar hp value. The resistance for each one percentof grade requires an additional 9.2 kg/t. Each degree of curvature requiresand additional about 0.37 kg/t. The influence of Rolling Resistance on DB


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horse power will be explained later. It should be clear that the Draw barhorsepower decreases with increased speed.

5.1.5 Horsepower Required to Pull a given Train Load

The calculations to find the Drawbar horsepower to pull a given train up aspecified grade and curvature can also be made.

Drawbar HP required =

Resistance X Wt. of Freight Car X No. of Freight Cars X kmph

270

Draw bar horsepower requirements will increase with increased speed.

5.2 Resistance

5.2.1 Rolling Resistance

The rolling resistance of a train can be determined by formula isgenerally is taken from tables and curves based on formula. The most widelyused of such formulae is the "Davis Formula". Rolling resistance isgenerally expressed in kg/t and is summation of Flange Resistance,Journal Resistance and Air Resistance.

Other things being equal, total Rolling Resistance increases as speeds

increase.

5.2.2 Grade Resistance

Grade resistance, expressed in kg/t , is independent of and unrelatedto train speed. It is due to the force of gravity. It is always equal to 10kg/tonne for each percent of grade as illustrated in the calculations below.

1 m rise1% Grade =

100 m distance

when Weight, W = 1 tonne = 1000 Kg

RG = 1/100 x 1000 Kg = 10 Kg

Grade resistance = 10 Kg per 1 % of grade.

Rise in elevation x 100 x RG (10kg/t)Total Grade Resistance =

Distance travelled .

Comment [D1]:


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5.2.3 Curve Resistance

A one degree curve is a curve whose central angle extends to a chordof 30.48 m (100 feet). A 30.48 m (100 feet ) chord is 1/360 of a completecircle, the radius of a 1' curve is 1746.5 m (5730 feet). Curve resistance isexpressed in kg / t / degree.

Degree of curvature = 5730 / Radius in feet or1746 / Radius in m

5.3 Tractive Effort

Tractive effort is defined as the turning force produced at the rails bythe driving wheels. Tractive Effort can be expressed mathematically asfollows for an AC locomotive.

Tractive Effort = Traction Horsepower x 315 mile-Ibs/hr / Speed in miles perhour

orTraction Horsepower x 230 km-kg/hr / Speed in km per hour

a. Tractive effort depends on five major factors:

I. Horsepower of the diesel engine.II. Ability of the main generator.

III. Ability of the traction motors.IV. Gear ratio.V. Adhesion

Weight on driving wheels.

Rail condition.

Wheel Slip Control System.

Inverter System.

b. The effect of the above factors on tractive effort is explainedbelow:

i) Horsepower of the Engine

HP of the diesel engine primarily determines the possible TE alocomotive can develop at the rims of the driving wheels. T.Ecalculations use the Traction HP for calculation purposes.

With an increase in the horsepower of the engine, either T.E. ofthe locomotive will increase for the same speed or speed will beincrease with the same T.E.

ii)Abili ty of the Main Generator


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The main generator is the first step in the transmission of enginehorsepower to the wheels. The main generator converts themechanical power into electrical energy, referred to as kW. Thiselectrical energy is then used by the traction motors to turn thelocomotive wheels. kW are measured by the following formulas :

Main Generator Voltage x Main GeneratorCurrent

Main Generator Kilowatts =1000 W per kilowatt

Tractive Horsepower = Main Generator Kilowatt /0.746 HP perkilowatt

The generator can produce any combination of amperage and voltagewithin the rated power range of the locomotive.

iii)Abi li ty of the Tract ion Motors

Traction motors transform the electrical energy of the maingenerator into mechanical force to turn the locomotive wheels. At lowspeeds, the traction motors must be capable of operating at theirthermal limit. Maximum locomotive speed is limited by the saferotational speed of the armature. In a DC motor, the armaturewindings limit the maximum speed of the armature to approximately2400 RPM. In an AC motor for the GT46MAC, the induction rotorallows the operating RPM to increase to 3600 RPM.

The ratings of the traction motors also affect the "MinimumContinuous Speed" of a DC locomotive, as well as the tractivehorsepower available for transmission to the motors. With an AClocomotive, however, "Minimum Continuous Speed" is not aconsideration. With AC traction motors, the locomotive can be put tofull throttle at standstill without any damage to the motors.

iv) Effect of Gear Ratio

At full load, a given power output will produce a correspondingrotor speed regardless of gear ratio. The effect of changing gear ratiois to change the train speed at which full load can be appliedcontinuously without thermal damage to the motors.

Therefore:

1. Increasing the gear ratio reduces the minimum speed (henceincreases tonnage) at which a given locomotive can operatewithout heat damage to the motors.

2. Reducing the gear ratio, the maximum speed at which a givenlocomotive can operate without mechanical damage to the motors.


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v)Adhesion

Adhesion can be defined by the following locomotive formula:

% Adhesion = Tractive Effort (kg) X 100/ Locomotive Weight

There are three classes of adhesion:

Required (Train Weight and Grade dependent)

Available (Operation under a given set of rail conditions)

Developed (Locomotive capability through enhancements-wheelslip control)

The adhesion rating of a locomotives depends upon confidencelevel. This means that at a confidence level of 98%, the user cancount on the locomotive developing the given adhesion factor 98% ofthe time. This is also termed as "All Weather Adhesion".

There are cases where trains can be dispatched with a lowerconfidence level and a higher adhesion requirement. For example,trains may be dispatched during the summer months at a lowerconfidence level i.e. the user is counting on higher adhesions becauseof good weather conditions. Under inclement weather conditions, thelocomotives can be dispatched at a higher confidence level of makinga successful trip as the rail conditions deteriorate. There is a large gainin dispatchable adhesion as the confidence level drops to say 80 %.This means that if one counts on the locomotive to produce 43%

adhesion, it will probably make the run successfully only 80% of thetime without help.

Weight on Driving w heels

The weight on the driving wheels is that portion of the entireweight supported by the wheels driven by traction motors. The weighton driving wheels is in an important factor in the locomotive's"adhesion". Adhesion is the grip produced by friction between the steelwheels and steel rails. Adhesion is required to keep the wheels fromslipping. In the modern locomotives which allow "wheel creep"(controlled wheel slip), however, the maximum tractive effort can bemuch higher due to the precise control of the wheel creep systems.

Rail Condit ions

With a given weight on rails, adhesion depends on railconditions. Dampness, water, leaves, rust, ice, frost, and oil causerails to be slippery. With GT46MAC locomotive, the adhesion mayTEMPORARILY reach as much as 45% (with ideal rail conditions).Practical year round adhesion factor may be as low as 33 %.

Wheel Slip Control System


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The wheel slip control system used on a locomotive can have a

dramatic effect on the adhesion level achieved. Until the introductionof the "Super Series" wheel slip control system, all wheel slip controlsystems were "corrective" type systems. In other words, they operatedunder the principle that all wheel slip is bad and would reduce power totraction motors to control the slip.

The introduction of "Super Series" improved dispatchableadhesion. The "Super Series" wheel creep control system allows thewheels to exceed ground speed by a certain percentage, depending onrail conditions, to improve adhesion. Super Series is activatedautomatically through the control system.

The introduction of AC technology also improves the wheelcreep control system due to its rapid response. In a DC locomotive,power is modulated by varying the DC field current of the maingenerator. There is an inherent lag time as the main generator'smagnetic field requires time to collapse. With the AC locomotive, thewheel creep corrections are far more rapid as the devices that controlthe power output to the AC traction motors (called Gate Turn OffThrystors, or simply GT0s) can have their switching sequence changedalmost instantaneously. Power corrections are much more rapid andsmoother with the AC traction equipped locomotive.

Inverter System

GT46MAC locomotive utilizes a system called "truck control",where one inverter controls all of the axles within a truck unlike GEwhich uses single axle inverter system i.e. one inverter per axle.

While "truck control" system has less number of physicalcomponents to maintain, this has the disadvantage of the powerreduction in the event of an inverter failure.

5.4 Dynamic braking effort

Dynamic braking effort may be considered as negative tractive effort. It isuseful for controlling train speed. Dynamic Brakes are normally not used tostop a train but are used to assist deceleration.

Dynamic Brakes are the preferred tool to control train speed on, manyrailroads for the following reasons:

i) It saves considerable brake shoe wear, the subsequent reduction inair brake use minimizes the chance of stuck brakes on the train.

ii) It eliminates the fuel inefficient practice of 'Stretch braking' a trainwith air brakes.


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5.5 Brake Effort

Braking effort for a train can be calculated by the Following formula:

Brake Effort = (-GRr+ CR+ CarR) x (Trailing load in tonne + Locomotive Wt.in tonne)

where GR = Grade resistance

CR = Curve resistance

CarR = Car resistance

5.6 Comparison Between Four Axle & Six Axle Locomotive

Six axle locomotive has 50% more Traction Motors than a four axlelocomotive resulting in:

Six axle locomotive has about 50% more tractive effort than a fouraxle locomotive.

Six axle locomotive weighs about 50% more than a four axlelocomotive.

Six axle locomotive's minimum continuous speed is approximately40% more than a four axle locomotives with equal horsepower.

With equal trailing tonnage, six axle locomotive's running time on a givenrun over the railroad is slightly longer than the four axle locomotive. This isbecause of the increased rolling resistance with the additional two motors /axles.

As a general rule, if the locomotive's primary mission is to haul trains athigh speeds (intermodal use), four axle locomotive is better suited. If thelocomotive's primary responsibility is heavy service over terrain with gradesand curves, six axle locomotive is better suited.


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1

Locomotive Design

There have been significant changes in locomotive technology duringpast 10-15 years. Modern electric and diesel-electric locomotives havesophisticated control systems that allow precise control for power applicationto the rails. These locomotives, therefore, have the ability to significantly out-perform older technology locomotives. Introduction of AC-AC technologyensures that the locomotives are dispatched to gain the maximum benefit ofthe increased dispatchable adhesion.

The following mechanical principles and mathematical formulasthat govern locomotive power application need to be clearly defined:

1 Locomotive Horsepower

There are four different horsepower ratings on a locomotive:

1.1 Brake horsepower.

Brake horsepower is measured at the engine crankshaft and is a measureof the TOTAL horsepower available for conversion to electrical energy atthe main generator plus the power required for driving accessory loads.

1.2 Traction Horsepower

Traction horsepower = Brake horsepower - Accessory loads

GT46MAC locomotive has the following accessory horsepowerdemands:

Auxiliary Generator.

Traction Motor/Main Generator Blower.

Air Compressor - mechanically driven by engine, but has a zerohorsepower load when unloaded and is disengaged. GT46MAChas a clutch which disengages when no compressed air isrequired.

Inertial Filter Blower Motor.

Radiator Cooling Fans - electrically driven by the companionalternator. GT46MAC utilises two speed-cooling fans to lessenthe horsepower demands for engine cooling when full cooling is notrequired.

AC Inverter Blowers - electrically driven by the companionalternator.


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2

Traction HP rating is the most commonly used rating when quotinglocomotive horsepower. When railroads dispatch loads on hp/ton basis,they in almost all cases use traction hp for calculations.

1.3 Net Traction Horsepower

Net Traction Horsepower = Traction Horsepower x Generator Efficiency

In case of GT46MAC locomotive, 0.94 is the efficiency of the main generator.

1.4 Rail Horsepower

Rail horsepower, the power delivered by the locomotive wheels at the rails,can be expressed by Rail Horsepower = Traction Horsepower xTransmission Efficiency

Transmission efficiencyis through:

Main Generator

Switch Gear

Cables

Traction Motors

Traction Motor Axle Gears.

Inverters

1.5 Draw Bar Horsepower

The power developed at the draw bar called Draw Bar Horsepower and is theactual horsepower used to pull a trailing load. It is the engine to generatorhorsepower minus electrical transmission losses minus horsepowernecessary to move the locomotive only.

Drawbar Horsepower =

{(Engine to Generator H.P. x Transmission Efficiency) - (Loco weight x locomotiveresistance x kmph)}

270 kg km per hour

Due to the fact that the formula includes "locomotive resistance" and kmph, itis necessary to specify the grade and curve condition as well as the speed ofmovement to obtain draw bar hp value. The resistance for each one percentof grade requires an additional 9.2 kg/t. Each degree of curvature requiresand additional about 0.37 kg/t. The influence of Rolling Resistance on DB


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horse power will be explained later. It should be clear that the Draw barhorsepower decreases with increased speed.

1.6 Horsepower Required to Pull a given Train Load

The calculations to find the Drawbar horsepower to pull a given train up aspecified grade and curvature can also be made.

Drawbar HP required =

Resistance X Wt. of Freight Car X No. of Freight Cars X kmph

270

Draw bar horsepower requirements will increase with increased speed.

2 Resistance

2.1 Rolling Resistance

The rolling resistance of a train can be determined by formula isgenerally is taken from tables and curves based on formula. The most widelyused of such formulae is the "Davis Formula". Rolling resistance isgenerally expressed in kg/t and is summation of Flange Resistance,Journal Resistance and Air Resistance.

Other things being equal, total Rolling Resistance increases as speeds

increase.

2.2 Grade Resistance

Grade resistance, expressed in kg/t , is independent of and unrelatedto train speed. It is due to the force of gravity. It is always equal to 10kg/tonne for each percent of grade as illustrated in the calculations below.

1 m rise1% Grade =

100 m distance

when Weight, W = 1 tonne = 1000 Kg

RG = 1/100 x 1000 Kg = 10 Kg

Grade resistance = 10 Kg per 1 % of grade.

Rise in elevation x 100 x RG (10kg/t)Total Grade Resistance =

Distance travelled .

Comment [D1]:


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4

2.3 Curve Resistance

A one degree curve is a curve whose central angle extends to a chordof 30.48 m (100 feet). A 30.48 m (100 feet ) chord is 1/360 of a completecircle, the radius of a 1' curve is 1746.5 m (5730 feet). Curve resistance isexpressed in kg / t / degree.

Degree of curvature = 5730 / Radius in feet or1746 / Radius in m

3 Tractive Effort

Tractive effort is defined as the turning force produced at the rails bythe driving wheels. Tractive Effort can be expressed mathematically asfollows for an AC locomotive.

Tractive Effort = Traction Horsepower x 315 mile-Ibs/hr / Speed in miles perhour

orTraction Horsepower x 230 km-kg/hr / Speed in km per hour

a. Tractive effort depends on five major factors:

I. Horsepower of the diesel engine.II. Ability of the main generator.

III. Ability of the traction motors.IV. Gear ratio.V. Adhesion

Weight on driving wheels.

Rail condition.

Wheel Slip Control System.

Inverter System.

b. The effect of the above factors on tractive effort is explainedbelow:

i) Horsepower of the Engine

HP of the diesel engine primarily determines the possible TE alocomotive can develop at the rims of the driving wheels. T.Ecalculations use the Traction HP for calculation purposes.

With an increase in the horsepower of the engine, either T.E. ofthe locomotive will increase for the same speed or speed will beincrease with the same T.E.


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5

ii)Ability of the Main Generator

The main generator is the first step in the transmission of enginehorsepower to the wheels. The main generator converts themechanical power into electrical energy, referred to as kW. Thiselectrical energy is then used by the traction motors to turn thelocomotive wheels. kW are measured by the following formulas :

Main Generator Voltage x Main Generator CurrentMain Generator Kilowatts =

1000 W per kilowattTractive Horsepower = Main Generator Kilowatt /0.746 HP perkilowatt

The generator can produce any combination of amperage and voltagewithin the rated power range of the locomotive.

iii) Ability of the Traction Motors

Traction motors transform the electrical energy of the maingenerator into mechanical force to turn the locomotive wheels. At lowspeeds, the traction motors must be capable of operating at theirthermal limit. Maximum locomotive speed is limited by the saferotational speed of the armature. In a DC motor, the armaturewindings limit the maximum speed of the armature to approximately2400 RPM. In an AC motor for the GT46MAC, the induction rotor

allows the operating RPM to increase to 3600 RPM.

The ratings of the traction motors also affect the "MinimumContinuous Speed" of a DC locomotive, as well as the tractivehorsepower available for transmission to the motors. With an AClocomotive, however, "Minimum Continuous Speed" is not aconsideration. With AC traction motors, the locomotive can be put tofull throttle at standstill without any damage to the motors.

iv) Effect of Gear Ratio

At full load, a given power output will produce a correspondingrotor speed regardless of gear ratio. The effect of changing gear ratio

is to change the train speed at which full load can be appliedcontinuously without thermal damage to the motors.

Therefore:

1. Increasing the gear ratio reduces the minimum speed (henceincreases tonnage) at which a given locomotive can operatewithout heat damage to the motors.


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2. Reducing the gear ratio, the maximum speed at which a givenlocomotive can operate without mechanical damage to the motors.

v) Adhesion

Adhesion can be defined by the following locomotive formula:

% Adhesion = Tractive Effort (kg) X 100/ Locomotive Weight

There are three classes of adhesion:

Required (Train Weight and Grade dependent)

Available (Operation under a given set of rail conditions)

Developed (Locomotive capability through enhancements-wheelslip control)

The adhesion rating of a locomotives depends upon confidencelevel. This means that at a confidence level of 98%, the user cancount on the locomotive developing the given adhesion factor 98% ofthe time. This is also termed as "All Weather Adhesion".

There are cases where trains can be dispatched with a lowerconfidence level and a higher adhesion requirement. For example,trains may be dispatched during the summer months at a lowerconfidence level i.e. the user is counting on higher adhesions becauseof good weather conditions. Under inclement weather conditions, thelocomotives can be dispatched at a higher confidence level of making

a successful trip as the rail conditions deteriorate. There is a large gainin dispatchable adhesion as the confidence level drops to say 80 %.This means that if one counts on the locomotive to produce 43%adhesion, it will probably make the run successfully only 80% of thetime without help.

Weight on Driving wheels

The weight on the driving wheels is that portion of the entireweight supported by the wheels driven by traction motors. The weighton driving wheels is in an important factor in the locomotive's"adhesion". Adhesion is the grip produced by friction between the steelwheels and steel rails. Adhesion is required to keep the wheels from

slipping. In the modern locomotives which allow "wheel creep"(controlled wheel slip), however, the maximum tractive effort can bemuch higher due to the precise control of the wheel creep systems.

Rail Conditions

With a given weight on rails, adhesion depends on railconditions. Dampness, water, leaves, rust, ice, frost, and oil causerails to be slippery. With GT46MAC locomotive, the adhesion may


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7

TEMPORARILY reach as much as 45% (with ideal rail conditions).Practical year round adhesion factor may be as low as 33 %.

Wheel Slip Control System

The wheel slip control system used on a locomotive can have adramatic effect on the adhesion level achieved. Until the introductionof the "Super Series" wheel slip control system, all wheel slip controlsystems were "corrective" type systems. In other words, they operatedunder the principle that all wheel slip is bad and would reduce power totraction motors to control the slip.

The introduction of "Super Series" improved dispatchable

adhesion. The "Super Series" wheel creep control system allows thewheels to exceed ground speed by a certain percentage, depending onrail conditions, to improve adhesion. Super Series is activatedautomatically through the control system.

The introduction of AC technology also improves the wheelcreep control system due to its rapid response. In a DC locomotive,power is modulated by varying the DC field current of the maingenerator. There is an inherent lag time as the main generator'smagnetic field requires time to collapse. With the AC locomotive, thewheel creep corrections are far more rapid as the devices that controlthe power output to the AC traction motors (called Gate Turn OffThrystors, or simply GT0s) can have their switching sequence changedalmost instantaneously. Power corrections are much more rapid and

smoother with the AC traction equipped locomotive.

Inverter System

GT46MAC locomotive utilizes a system called "truck control",where one inverter controls all of the axles within a truck unlike GEwhich uses single axle inverter system i.e. one inverter per axle.

While "truck control" system has less number of physicalcomponents to maintain, this has the disadvantage of the powerreduction in the event of an inverter failure.

4 Dynamic braking effort

Dynamic braking effort may be considered as negative tractive effort. It isuseful for controlling train speed. Dynamic Brakes are normally not used tostop a train but are used to assist deceleration.

Dynamic Brakes are the preferred tool to control train speed on, manyrailroads for the following reasons:

i) It saves considerable brake shoe wear, the subsequent reduction inair brake use minimizes the chance of stuck brakes on the train.


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8

ii) It eliminates the fuel inefficient practice of 'Stretch braking' a trainwith air brakes.

5 Brake Effort

Braking effort for a train can be calculated by the Following formula:

Brake Effort = (-GRr+ CR+ CarR) x (Trailing load in tonne + Locomotive Wt.in tonne)

where GR = Grade resistance

CR = Curve resistance

CarR = Car resistance

6 Comparison Between Four Axle & Six Axle Locomotive

Six axle locomotive has 50% more Traction Motors than a four axlelocomotive resulting in:

Six axle locomotive has about 50% more tractive effort than a fouraxle locomotive.

Six axle locomotive weighs about 50% more than a four axle

locomotive.

Six axle locomotive's minimum continuous speed is approximately40% more than a four axle locomotives with equal horsepower.

With equal trailing tonnage, six axle locomotive's running time on a givenrun over the railroad is slightly longer than the four axle locomotive. This isbecause of the increased rolling resistance with the additional two motors /axles.

As a general rule, if the locomotive's primary mission is to haul trains athigh speeds (intermodal use), four axle locomotive is better suited. If thelocomotive's primary responsibility is heavy service over terrain with grades

and curves, six axle locomotive is better suited.


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15. Locomotive Testing And Painting

15.1 Locomotive Test

General Motors adheres to following concept/philosophy:

All individual assemblies and components are tested during thelocomotive assembly either at the GM works or at the supplier end.

All electronic and air brake equipment are to be left unplugged duringassembly.

15.2 Testing should verify/ audit integration of all locomotive system and sub-system.A very elaborate test procedure for the complete locomotive is followed by EMD beforethe locomotive is put on line. The test procedure is based on the relevant EngineeringTest Instructions, defects found on previous units and reports from the service

department. In case of GT46MAC, which would be a prototype even as it is electricallysimilar to SD70MAC, the procedure for the first locomotive is a more exhaustive andstringent test protocol. After completion of testing, the test records are scrutinised. Astest checks are completed or at the end of the shift, they are to be initialled by the testpersonnel opposite to the test numbers.

After the preliminary inspection, Hi Pot Test for power & control circuits includingDynamic brake is done to ensure that no damage has been done during productionassembly. It is followed by continuity check on various sub-system and installation ofEM2000 modules. All the connections to other electronic system are completed andpower-up & self-tests done. During testing the following safety procedure are taken intoconsideration.

The second stage of testing starts with pre-lube of engine. The engine is startedand all mechanical and electrical checks including Siemens Commissioning checks arecompleted. A pre-load test is done to confirm that other systems are ready for load test,e.g., Inertial blower and also customer specific feature, if any. During the load test, thelocomotive power output is dissipated in the dynamic grids to confirm the integrity of thecabling of Dynamic brake system. The locomotives not having self load Test feature,are connected to external grids. During the Load Test, measurement of cab noise andvibrations at few selected locations are also done.

Finally, in the last stage, the locomotive is prepared for Track Test. Air brakesystem is checked to ensure its integrity, besides any other specific feature whichremains to be checked. The track test is done on a test track of 1/2 miles length approx.with maximum permissible speed of 35 kmph.(located in Diesel Division). it is done forsingle unit as well as multiple unit. The functioning of speed indicator, ground relay andpneumatic controls checked, besides push pull test for Dynamic brake Drag operation.

A pre-delivery inspection is carried out by down-loading all the fault/unusualmessage encountered during testing of the loading and a final inspection carried outbefore dispatching the locomotive.


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On microprocessor units whenever a module is installed or removed, power supplyto the computer is switched off. A wrist grounding strap is used.

All the electronic system should be disconnected prior to megger and hi-pot testing. To check the continuity and test point voltage, only digital type meter should be used

Under open circuit condition, the main generator should not be excited. The meter leads and jumpers should not touch the carbody ground from 15V

circuits. Test points in 15 Volt supply should not be jumpered. Engine blow-out must be performed before starting the engine if the engine has

been down for eight hours or more.

Some preliminary tests like checking of hand brakes, wheels, air compressor,engine oil, dust etc. are done before starting the actual testing. The testing consists ofthe following well defined steps sequentially -

Hi Pot test Trainline continuity Lighting circuit Blower/Fans operation Power contactor operation EM2000 module application and computer preliminary test EM 2000 system integration Dynamic brake signals Sanding TM blower shutter Engine run Engine start AG checks Air compressor control, low air engine speed up & air system safety valve TCC phase module temperature control TCC power supplies, systems and operations test Excitation test Preload Load test Track test Traction inverter cut-out Multiple unit operation Pre delivery test

15.3 Locomotive Painting:

The locomotive after complete testing is brought to specially designed paintingbooth. The painting is done as per the following sequence:

Preparatory booth

The locomotive is washed, degreased and deburring of all external welded jointscompleted. The appropriate areas e.g., consoles in the cab, TG fan, valves & pipes,rubber side bearer etc. are masked.


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Painting Booth

There are two painting booths where the following activity are done:-

The external is coated with the epoxy primer.

The cab and long-hood exterior surfaces are given polyurethane paint coat.

The polyurethane masked stickers as per the painting style ( pertaining to railroad name, road number and longitudinal strips) are affixed at the appropriatelocations. The masks are removed after the final painting.

The external surfaces including underframe & bogies are then given one coat ofpolyurethane paint. Two hours drying time is given before applying another coatof the same paint. The dry & wet gauges are used to measure the paint thickness. Normally the paint thickness is of the order of 6 thou and its uniformity over the

surface is maintained by the experience of the painter.

EMD also have separate painting booth for small piece parts and underframe.The underframe assembly after fabrication is given one coat of epoxy paint before &after piping and cabling. Similarly assembled equipment rack is also given one coat ofepoxy paint.

16. Visits To Various Facilities16.1 Visit To M/S Atchison Castings/Kansas -USA

Atchison Castings Corporation (ACC) was re-organized in 1991 with the purpose

of becoming a broad based foundry company. ACC products are iron and steelcastings ranging in size from 1 to 120, 000 lb. ACC customers are leaders in their ownfield and include General Motors, Caterpillar, General Dynamics, Rockwell International,Westinghouse, John Deere, General Electric, Morrison Knubsen, Bombardier, ABB etc.

The company was founded in Atchison, Kansas in 1872 to supply iron castings tothe Railroads. In 1956, the facility was acquired by Rockwell International. In 1991,

ACC acquired Rockwells Foundry in Atchison, Kansas and Machine Shop in St.Joseph, MO.

All the castings are electronically analysed in the design development process

and create modifications using solidification software techniques, which optimise qualityand cost without adversely affecting functional performance. M/s Atchison Casting isusing their proprietary bonding agent. They have also very excellent sand recoverysystem.

All the casting ranges produced by ACC Castings are machined in fully finishedcondition at St. Joe division (Atchison Castings Machine Shop) which is a separateunit.


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The casting of truck requires one piece thin walled, high integrity, frame

castings. With solidification and mould filling simulation on computer, the company isable to achieve excellent quality. Bogie frame for HTSC truck have been developed asU-section in place of traditional Box-section. This design eliminates use of cores. The

use of cores increase the cost of production and decrease the quality of castings. M/sGM/EMD and M/s Atchison Castings have collaborated for development of this design.

It is learnt that for future supplies of cast steel HTSC bogie frames to DLW, M/sAtchison Casting has entered into a TOT contract with M/s Simplex Engg. & FoundryWorks/Bhilai.

16.2 Visit To M/S Lord Corporation/ Erie/ PA - USA

Lord Corporation have facilities for designing, manufacturing and testing of metalbonded rubber components as per customer requirements.

Main component supplied to EMD is metal bonded rubber spring used insecondary suspension and metal bonded rubber bushes for various joints.

The design of metal bonded rubber spring is done on FEM package to optimisethe profile of rubber to avoid stress concentration.

Lord Corpn. have modern manufacturing facility for manufacture of metalbonded rubber components. Transfer moulding process is followed for moulding therubber. For bonding between metal and rubber, they use special type of chemicaldeveloped for this purpose.

M/s Lord corporation have extensive fatigue testing facilities. Company has setup new testing shop which is equipped modern fatigue testing machines, vibrationshaker which are controlled by computer various data are recorded and analysedfurther. since major percentage of their products are supplied to aircraft industry, sothey have installed three axis machines by which they can conduct all modes of testingsimultaneously. The locomotive components are required to be tested for one millioncycle at varying frequency.

17. Computer Aided Design By Unigraphics

EMD uses Unigraphics package which is a completely integrated software and isused for drawing-drafting and modelling. The underframe, car body, cab, bogie frameand other bogie components such as wheels, axles, axle box, traction motors,suspension and brake rigging components are generated by solid modelling andassembled together. The package is very useful for preparation of layouts and study ofinfringement/clearances between different components of bogie. The package alsoenables calculation of weights, moment of inertia and centre of gravity which arerequired for vehicle dynamics studies. The models prepared by Unigraphics can be


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transferred to ANSYS for finite element analysis. The package is supported by standardlibrary of components such as nuts, bolts, screws, etc.; the components most commonlyused can be generated and can also be included in the library.

Sizing of various cross section was done by keeping section modules of this

bogie frame same with a similar bogie frame with box section. Afterwards optimisationof sections were carried out by FINITE ELEMENT ANALYSIS by applying load cases.

18. Recommendations

18.1 DLW should install Unigraphics system and ANSYS FEM package not only tofully assimilate EMD technology but also develop expertise in design of newlocomotives of horse power ranging from 3000 to 5000 hp with EMD 12 cylinder and20 cylinder engines.

18.2 DLW should follow EMD project management and design review process in

design and manufacture of locomotives and assemblies.

GT46MAC LOCOMOTIVE

Specification

Track Gauge 1676 mmTotal Weight on Rails 126 tDesign Speed 100 kmphWheel Arrangement Co-Co Height

(top of rail to top of cooling fan) 4,120 mmOverall Length Over Buffers 21, 245 mmFuel Capacity 6,000 LCooling Water Capacity 1144 L

Performance Specification

TCV 4,000Starting Tractive Effort 540 kNBraking effort capability 270 kN

Engine 16-71OG3B


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Turbocharger High EfficiencyFuel Injection Unit Fuel Injection

Traction Technology AC-AC

No. of invertors One/truck

EM2000 Advanced Computer

32-bit microprocessorReduction in modules and components compared to Dash-2 series controlsImproved reliability and performanceInformation can be downloaded to a laptop computerFlexible and expendable to accommodate future system enhancementsComplete self-diagnostics

Archived unit history data,

HTSC Bogie

No wearing surfaces extends bogie overhaul intervals to 1.6 million kmDual high adhesion and high speed

Available gear ratios for heavy haul and passenger operation

Cab Features

Air operated windshield wipers

Dual desk type control console - optionalMulti-resettable vigilance controls - optional

Air System Direct drive air compressor

Brake System Electronic Air Brake System

Reliability and Serviceability

90-day maintenance intervalsAC motors doubles traction motor life

No running maintenance required* No brushes, commutator, or rotor insulation* No flashovers

Bogie Inverter Control* High level of reliability with fewer parts

1.6 million kilometre overhaul with HTSC Bogie6-year engine overhaul period


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Safety Aspects

Increased CrashworthinessProvision of Anti-climber


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WDG4 locoDESCRIPTION OF BOGIE

1. WDG4 loco is provided with HTSC (High Tensile Steel Cast) Bogies.2. This is a three-axle bolster-less bogie with two-stage suspension with helical coil springs in primary

stage and rubber compression springs in secondary stage of suspension.3. The locomotive car body weight is transferred directly to the bogie frame through four rubber

Compression spring assemblies.

4. The lateral stiffness of rubber springs is utilized to provide lateral guidance at the secondary stageand provide the yaw stiffness for stability.

5. Lateral spacing of rubber springs affords stability of locomotive on curves and damping provided byrubber springs and yaw dampers prevents nosing at high speed.

6. The bogie frame is supported on axles through soft primary suspension consisting of twelve

single helical coil springs, two springs mounted on each axle box, to provide ride quality andequalization of wheel-set loads.

7. Shims of different thickness are provided above the outer and inner rubber compression springassemblies for axle load equalization.

8 Centre pivot does not take any vertical load and is used only for transfer of traction and brakingforces.

9.. The bogie is fitted with lightweight asynchronous, axle hung, nose suspended traction motors.

10. All traction motor nose positions are oriented to the same side of each axle within the bogie frame.

11. The relatively stiff secondary suspension, uni-directional arrangement of traction motors and lowcenter pivot limits the weight transfer between axles during adhesion.

12.. For wheel-set guidance in longitudinal mode, guide link fitted with rubber bush is provided betweenaxle box and bogie frame to cushion the longitudinal thrust.

13.. Traction and braking forces are transmitted from wheel-set to bogie frame through these guidelinks.

14. Axle boxes are fitted with tapered roller bearings with integrated bearing adapter.

15. Six vertical hydraulic dampers are provided in primary stage between axle and bogie frame, onewith each nest of primary springs on the axle box.

16. Two hydraulic yaw dampers are provided in secondary stage between bogie frame and the locounder frame to supplement the damping provided by rubber springs.


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17. The yaw dampers are oriented in such a way that they provide damping both in lateral and yawmodes.

18 Safety links are provided at the lateral stop locations between bogie frame and the under frame.

19 These links serve to prevent separation of the bogie from the locomotive car body in case ofderailment and also provide means of lifting the bogie along-with the locomotive car body.

20 Safety hoops are installed between each axle interlock bracket.

21. The locomotive is provided with conventional brake gear arrangement with single composition brakeshoe per wheel.

Ride Characteristics of WDG4 locomotive

Designed for 110 km/h Axle load of 21.0t Maximum Lateral force 4t Derailment coefficient


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Basic design is similar to that of WDG4 bogie the differences are highlighted Axle load 19.5t AA1 (B1) wheel arrangement Lighter bogie frame (reduction of section of end transom).

Softer Primary helical springs. Axle size is smaller of axle 3 & 4. Secondary rubber lateral stiffness made softer Different shimming due to difference in axle load. Stiffer guide links. Use of happy pads. Different Damper capacity.

Performance observed

Tested at Pueblo USA On standard gauge Tested up to Max speed of 180km/h Lateral force, Derailment coefficient, Acceleration/RI (Vertical & Lateral) were measured. Curving performance was checked.Design parameters

Speed potential of 180 km/h Lateral force 3t Derailment coefficient < 1

RI Vertical & Lateral < 4.0 Acceleration Vertical & Lateral mode < 0.35g For track standards maintained to C&MI Vol-1Ride Characteristics of WDP4 locomotive

Oscillation test was carried on at Pueblo(USA) speed of 180km/h Max. Lateral force observed was 1.5t Derailment Coefficient was 0.18 RI Vertical at 180 km/h was 3.66 RI Lateral at 180 km/h was 3.42 Acceleration in Vertical and Lateral mode were within limit(lessthan 0.19g/0.15g)


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LUBE OIL SYSTEM

INTRODUCTION

The complete engine lubrication system is a combination of four separate systems. They

are the main lubricating system, the piston cooling system, the scavenging system and thesoak back or turbo lube system.

Each system has its own oil pump. The main lube oil pump and piston cooling oil pump

(although individual pumps) are contained in the same housing and driven from acommon drive shaft. There are separate pumps for scavenging and turbo lube oil system

also.

The main lube, piston cooling and scavenging pumps are driven mechanically fromengine through accessory gear train at the front of the engine. The turbo soak back pump

is driven electrically by an AC motor.

System lube oil capacity: 950 Litres/ 1450 Ltrs, The oil level is checked by an oil gauge

(Dip Stick). The oil level should be between low and full marks when the engine is at idle

and the oil is hot (66C)The system lube oil pressure is 125 psi. (LOPS setting: 8-12 psi at idle and 25-29 psi at

full speed)

The filter by pass valve is set at 40 psi.The turbo soak back oil pressure is 50 psi.

Main lubricating system

The main lubricating oil system supplies oil under pressure to most of the moving parts

of the engine. It takes oil from strainer housing and sends it to main oil manifold, locatedabove the crank shaft. System oil pressure is limited upto 125 psi by a relief valve

situated in the passage between the pump and the manifold.

Oil tubes at the center of each main bearing A frame conduct oil from the main

manifold to the upper half of the main bearings. Drilled passages in the crankshaft supplyoil to the connecting rod bearings, torsional damper and accessory drive gear at the front

of the crank shaft. Leak off oil from adjacent main bearings lubricates the crank shaft

thrust bearings.Oil from manifold enters the gear train at the rear of the engine, at the idler gear stub

shaft. Oil passages in the base of the stub shaft distribute the oil. One passage conducts

oil upward to the left bank camshaft drive gear stub shaft bracket through a jumper, anddownward to the lower idler gear stub shaft and bearing. Another passage conducts oil to

the right bank camshaft drive stub shaft bracket and on to the turbocharger oil filter

supply line. After passing through the filter, the oil enters the return line, returning to theupper idler gear stub shaft bore and bearing. Filtered oil enters the turbocharger oil

system from upper idler gear stub shaft. An oil pressure line connects to the top of

turbocharger oil manifold, adjoining the filter. This oil pressure line goes to the low oil

pressure device in the governor.Oil enters the hollow bore camshafts from the camshaft drive stubshafts. Radial holes in

the camshaft conduct oil to each camshaft bearing. An oil line from one camshaft bearing


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at each cylinder supplies oil to the rocker arm shaft, rocker arm cam follower assemblies,

hydraulic lash adjusters and injector rocker arm button. Leak off oil returns to the oil pan.

Passages in the turbocharger conduct oil to the turbo charger bearings, idler gear, planetgear assembly and auxiliary drive bore.

Piston cooling oil system

Piston cooling oil system pump receives oil from a common section with the main lube

oil pump and delivers oil to the two piston cooling oil manifolds extending the length of

the engine, one in each side. A piston cooling oil pipe at each cylinder directs a stream ofoil through the carrier to cool the underside of the piston crown and the ring belt. Some of

the oil enters the grooves in the piston pin bearing and the remainder drains out through

holes in the skirt to the sump.


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Scavenging oil systemThe scavenging oil system pump takes oil from the oil pan sump through the scavenging

oil strainer. The pump then forces the oil through the oil filters and cooler, which are

located at the equipment rack near the engine. Oil then returns to the strainer housing tosupply the main lube oil pump and piston-cooling pump with cooled and filtered oil.

Excess oil spills over a dam in the strainer housing and returns to the oil pan.


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Soak back oil system

To ensure lubrication of the turbo bearings prior to engine start, and the removal ofresidual heat from the turbo after engine shutdown, a separate lube oil pressure source is

provided, called soak back system. The working of this system is controlled

automatically by the locomotive control system.

The motor is timed to operate 35 minutes after each time it is started. Oil circulation

through the turbocharger is necessary prior to starting the engine and during the period

when the engine oil pressure is building up to provide proper lubrication.


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Turbo lube pump timing after shut down is based on the throttle position. Throttle

position is logged by the computer. If throttle remains in position for 2 minutes or more

the timing is as follows:

Throttle position Time

1

15 Mins2 20 Mins

3 25 Mins

4 30 Mins5 (or higher) 35 Mins

An AC motor driven pump draws lube oil from oil pan, pumps the oil through a filter and

head of the turbocharger oil filter directly into the turbocharger bearing area. The motor

driven pump and the filter are mounted on the side of the oil pan on the Right Bank of theengine.

A 55 psi relief valve, located in the head of the filter, controls the system pressure. A

bypass valve set at 70 psi is also located at the filter head. This valve will open to permit

oil from the soak back pump to bypass the filter element, if clogged. So that, lubricationcan be supplied to the turbocharger to prevent turbo damage.

SYSTEM COMPONENTS

Lube oil strainer housing

Lube oil strainer housing is situated at the accessory end of the crank case It contains onestrainer (coarse) at the suction side of the scavenging pump and two strainers (fine) at the

suction side of the main lube and piston cooling pump.

An oil level is maintained in the strainer housing up to the bottom of the overflow

opening by the scavenging system. This oil serves as the supply for the main lube andpiston cooling system. Excess oil not used by these systems returns to the engine sump. A

spring-loaded valve is provided to drain the oil from the strainer housing into the engine

sump for strainer maintenance. Both of these valves are located under the filler cover.Normally oil is added to the engine by strainer housing.

STRAINER


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The scavenging oil strainer (coarse) is installed in the housing at the suction side of

scavenging pump. All oil for the scavenging system is drawn through it. Its duty is to

protect scavenging pump from foreign materials.Main and piston cooling oil strainers (Fine): They are two in numbers, installed within

the housing by a crab and hand wheel on the stud between the holes. Each strainer is

sealed at the top by a O ring seal to arrest leakage. Each strainer consists of an elementof pleated perforated metal core covered with mesh screening, and a metal cylinder that

encloses the element. Cylinder prevents collapse of the element in the event of high

pressure drop. The element is attached to the cylinder by a through bolt in the cylinder,which runs through the base of the element and is secured with a lock nut. The

unperforated outer cylinder provides a constant head of oil since suction is from the

bottom only and not through the entire length of the screen. Oil flow is from the bottom

of the strainer between the cylinder and the mesh screen, through the mesh screen and theperforated metal core into the center of the element, then out the top of the strainer.

Main Lube Oil and Piston Cooling pump

The main lube oil and piston cooling pumps are positive displacement helical gear typepumps contained in one housing. A spacer plate separates the two pumps between the

sections of the pump body. Each has individual oil inlet and discharge opening. The lubeoil and piston cooling pump assembly is mounted in the center of the accessory drive

housing, and driven by the accessory drive gear.

Discharge capacity of main lube oil pump: 229 GPM at 900 rpm

Discharge capacity of piston cooling pump: 109 GPM at 900 rpm

Scavenging Oil Pump

The scavenging oil pump is a positive displacement helical gear type pump, exactlysimilar to main and piston cooling pump except for the spacer between them. The

scavenging pump is mounted on the accessory housing in line with, and to the left of thecrankshaft, and is driven by accessory drive gear. The pump body, split transversely forease of maintenance, contains sets of mated pumping gears. The driving gears are

retained on the pump drive gear shaft by woodruff keys. The idler shaft is held stationary

in the housing by a setscrew, and the driven pump gears rotate on this shaft on bushings

pressed into the gear bores. The drive shaft turns in bushings pressed into the pump body.Pump discharge capacity: 405 GPM at 900 rpm.


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Lube oil Filter Tank

Lube oil filter tank is situated at the equipment rack in the front side of the engine. It

consists of 05 Nos. pleated paper type filter elements. Filter elements must be renewed if

filter tank pressure reaches 25 psi. at 8th

notch and 7 psi at idle.at 66C lube oil

temperature. A bypass valve is provided in the filter tank to bypass the filter during coldstart or plugged filter element. The bypass valve works at 40 psi differential pressure.

Lube Oil Cooler

The lube oil cooler assembly is positioned at an angle in the equipment rack at the frontside of the engine. The external construction of the cooler consists of a fabricated steel oil

tank surrounding the oil cooler core.

The cooling water returning from the radiators enters the cooler through flangeconnection at the top side, flows down through the cooler tubes and is discharged through

flanged connection at the bottom of the cooler.

The lubricating oil enters the shell space through a flanged connection near one end of

the cooler, flows transversely around the tubes and around the end of the baffles, andleaves the shell through a flanged connection near the opposite end of the cooler.

The coolant and the oil flow through the cooler in opposite directions to produce the

maximum cooling effect.

LUBE OIL COOLER


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Lube Oil Pressure Relief Valve

The lube oil pressure relief valve is installed on the lube oil cross over manifold, inside

the accessory gear train housing on the left side of the engine. This valve is accessible forinspection and service by removing the Engine Protection Device.

The purpose of the valve is to limit the maximum pressure of the lube oil entering the

engine oil system. When the lube oil pump pressure exceeds the spring tension on thevalve, the valve will be lifted off its seat and relieve the excess pressure. This oil drains

into the accessory housing and then into oil pan.

Turbocharger oil filter

The turbocharger oil filter provides additional protection for the high speed bearings andother lubricated areas of turbocharger, by filtering the oil just before it is admitted to the

turbocharger.

Oil enters the filter through a cast manifold and, after passing through the filter, returns tothe upper idler gear stubshaft and into the turbocharger. The filter element is of pleated

paper construction, and is disposable. The filter is mounted on camshaft drive housing at

the right bank of the engine. Some engines have disposable spin on type turbo lube filter.

The filters should always be filled with clean oil before installing on the engine.


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FORCED AIR SYSTEM

This is a centralised system for storing and providing clean air for all-purpose engine

requirement like cooling, combustion air and pressurisation of compartments etc. Itslocation is in between the TCCs and engine compartment. It is properly sealed so that

unfiltered air should not rush into it. Entry of air is done through inertial filters located ateither side of the locomotive car body and dirt blower expels separated dirt, out to the

atmosphere through the roof of the locomotive.Air that is drawn into the compartment is primarily to supply:

Combustion air for the diesel engine

Cooling air for MG, companion Alternator and rectifier bank

Cooling air for Traction Motors

Cooling air for Traction Inverter equipments

Pressurisation of engine room and electrical cabinets

BLOWERS

Various blowers used in this system are:1. M G BLOWER

Mounted on Aux. Generator on the front side closest to the Main Generator. Both MG

Blower and TM Blower are mounted on the same housing separated by a partition.It supplies air for:

Cooling Main Generator Rectifier bank, Main Generator, Companion Alternatorand finally to Engine Room.

Maintain slight positive pressure in the engine room

Part of this air is used by Air Compressor and thus reduces the load of its filter

assembly

2.

TM BLOWERMounted on Aux Generator on the front side away from the Main Generator. Itsupplies air for:

Traction Motor cooling

Generator pit operator operation

Main electrical cabinet pressurisation

Traction computer cooling

3. TCC ELECTRONIC BLOWERMounted at Central Air compartment. It is driven by AC motor powered by

Companion Alternator. This air is further filtered by paper filter located under each

filter cabinet. Used for:

Cooling and pressurising a part of the Inverter Cabinet containing DC LinkCapacitors, gate units and Traction Computers

4. TCC BLOWERS

There are two TCC Blowers, one for each cabinet. Its a 3 phase AC motor drivenblower powered by Companion Alternator. Initial command for blower operation

comes from TCC Computer and finally executed by EM 2000. They draw air directly

from the ambient across the modules and expel it across the R-2 snubber resistor.

They are used for supplying air for cooling phase module and cabinet.


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ENGINE AIR INTAKE FILTER (FIBER GLASS BAG)

Additional filtration is required for the air used by the engine. For this a fiberglass

bag filter element is used for engine intake air filter. It is equipped with pressureswitches to sense the pressure difference between turbocharger inlet and ambient. The

switches are located inside the electrical cabinet and connected by tubes to the turbo

inlet side of engine air filter and to ambient. They work as follows: If pressure difference exceed 356 mm/ 14of water column Filter Vacuum Switch

(FVS) will trip closed and display message will read (FILTER VACUUM

SWITCH TRIPPED)

If pressure difference reaches 610 mm/ 24of water column Engine Filter Switch

(EFS) trip close and EM 2000 will reduce engine speed and load to 6th

notch withthe display message (ENGINE AIR FILTERS ARE DIRTY- CHANG OUT

REQUIRED, POWER MAY BE LIMITED TO 6TH

NOTCH).

Hose stems are provided on the front of the electrical cabinet to take the manometerreading of pressure drops across the inertial air filter, the engine plus inertial air filters

and the electrical cabinet filters.


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14. Electrical Systems & Traction Alternator Design & Aux. SystemDesign

14.1 Locomotive Electrics - Basic AC-AC System:

The system basically uses diesel engine, alternator, rectifier, d.c. link,invertor(s) and asynchronous motors. The alternator is directly coupled to thediesel engine. The frequency of the alternator output varies with the speed ofdiesel engine. The voltage is rectified and the power is fed through a d.c. linkto the invertor of the tractive system. Drive system uses asynchronousmotors. Asynchronous motor when used on railway vehicle has to besupplied variable alternating voltage of variable frequency (VVVF). This isaccomplished by the invertor the input to which is d.c. voltage through d.c.link. All AC-AC diesel locomotives employ this principle. The number ofinvertors and the size of the alternator depends on the amount of energy to beconverted.

ENGINE GENERATOR INVERTOR TRACTIONMOTOR

G = M3 ~ 3~ 3 ~

The electronic control system ensures that the correct control inputs

are given to the invertor. It also controls and monitors the diesel engine, thealternator and the other auxiliaries of the locomotive. It is the central controlunit which ensures that the locomotive operates optimally.14.2 MainAlt ernator and Companion Alternator

Alternator is foot mounted with flange coupling with the engine.Alternator TA17 is a 3 phase, 10 pole machine equipped with twoindependent and interwoven sets of stator winding. It is basically twogenerators in one - two sets of stator windings, permanently connected inseries, work with a rotating field common to both the windings in order toprovide a higher generator output voltage, which is a basic requirement of alow current high voltage generator used on AC-AC locomotives.

The main alternator has a companion auxiliary generator CA 6 forpower supply to large auxiliaries. It is also the main excitation source for themain alternator. The companion alternator is an electrically independentmachine and is mechanically coupled on the main shaft of the tractionalternator. The companion alternator rotor field is excited directly by auxiliarysupply of the locomotive (74+4 VDC). It receives the excitation current fromthe auxiliary generator through slip rings located adjacent to the slip rings ofthe main generator. The output voltage is directly proportional to the speed ofrotation but varies to some extent with change in alternator temperature andload.


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Both these alternators are forced air cooled. A dedicated blower

coupled to the engine crankshaft provides cooling to the Alternator / Rectifiersystem. The air flow pattern has been depicted below.

Axial & Radial Cooling In EMDAlternator

AIR FLOW

STS CORESTACKS

AIR FLOW

COMPANION ALTERNATOR

RECTIFIER

ALTERNATOR MAIN WINDING

14.3 Rectifier

AC output from the main alternator is supplied to air cooled rectifier.The rectifier assembly consists of high current, high voltage silicon diodesconnected in 3 phase full wave bridge rectifier circuits. RC circuits areconnected to suppress the transients signal.

14.4 Traction Motor

The asynchronous motor with a squirrel cage rotor is the simplest ofall electrical machines. When fed by a 3- phase alternating voltage, amagnetic field rotates in the stator. The speed of rotation of this field is directlyproportional to the frequency of the A.C. voltage. The rotating magnetic fieldcauses the rotor to turn at a slightly lower speed due to electric slip. Thisdifference in speed is responsible for the development of the torque.

The only winding fed with voltage in the asynchronous motor is housedin stator. To prevent hot-spot developing in winding overhang, it is directlyventilated. The winding is impregnated under vacuum. There are no exposed


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metallic parts, so that excellent protection is assured. The rotor is squirreltype, i.e. it consists of un-insulated copper bars joint to sturdy short-circuitingrings. There is no commutator, sliprings, Brushgear or anything similar.

Following aspects are given primary importance while designing ACtraction motors :

Vibrations and shocks from track

Envelope dimensions - more torque packed in small space

Reliability - TM subjected to different elements like movement oflocomotive, dirt heat & humidity

Presence of transients

Requirement of starting and road characteristics

14.5 Electrical Contro l Cabinet No. 1 (HVC)

Electrical control cabinet is for mounting of the following mainequipment :-

Main Control Panel

DC Link switch gear

Braking contactors

Circuit breakers

EM2000 computer chassis

EM2000 support hardware

GFC, GFD & IMGF

SCR bridge Power supply for GTO1 & GTO2

TCC blower contactors - six numbers

IB1 ,IB2 , IBKBL1 , IBKBL2 transducers

Display Screen on ECC#1 door

Engine Control Panel

TMA transducer

74 V receptacles

The routine testing of HVC is an elaborate process . There is adedicated test station which is microprocessor controlled andhas the facility to check the important aspects related withperformance and reliability, viz., continuity of all the wires on the

cabinet and actual operation of the relays, switches andcontactors. All the test data is logged, abnormalities identifiedand a printout is taken for undertaking the rectification work.

The software for the test station is written in HP Basic. EM2000 Modules, which are not mounted at this stage, aretherefore not tested at EMD. The cabinet complete isdespatched to DD , London, OT.

14.5.1Design Aspects Of ECC#1


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Ventilation Engineering of the cabinet has been done based on

the cooling requirements of major components, e.g. powerchassis , EM2000 , SCR Bridge Assembly. Main duct has beenconstructed along the wall sided which branches to supply air tothe components.

The panel is modular so as to facilitate quicker assembly.

The cabinet is pressurised to avoid ingress of dust etc. Apressure of 2 to 3 of water gauge is maintained.

No electro pneumatic contactors are used on this cabinet.

Components and cables of a common electrical circuit aregrouped together (e.g. GFC, GFD, RE2 , RE32, CA32 and theSCR Bridge) in order to reduce EMC interference.

14.5.2 Electrical Cabinets 2 & 3

Electrical cabinet number two and three are smaller cabinets than theHVC. These cabinets consist of the following components:

Cabinet# 2.

Auxiliary Generator circuit breaker ST & STA contactors - for starting of engine. RE11 & RE12 BCASM - Battery Charging assembly Provision for Shunt DC DVR - Digital Voltage Regulator Inductor L4,5,6

Air Filter

Cabinet# 3 (AC Cabinet)

Cooling fan contactors -six numbers Terminal Boards MRPTs- Main reservoir pressure transducer DIP80 - Diode Panel and CMUX hardware for multiplexing Air Filter

146 EM 2000

EM2000 is a modern locomotive computer control system. Thesystem, has effectively replaced the outdated electronic and IC-basedcontrol systems used earlier. Some of the basic features of the system,

inter alia, are-

Significant reduction in number of control modules

Better fault detection of components

Self diagnostics and self tests to aid in troubleshooting

Memory archive and data snap shot

The main computer chassis contains the follow ing modules


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One CPU module which uses a 32 bit Motorola 68020 16 Mhzmicroprocessor

Three Digital Input/Output (I/O) modules ( DIOs)

One communication module (COM)

One Analogue to digital and digital to analogue module ( ADA)

One memory module ( MEM )

The computer chassis is split in the middle by a metal partition.The right houses the high speed data modules, CPU, MEM and COM.The left side houses the I/O handlers, i.e., ADA and DIOs. On the frontof all the above modules, Fault LEDs are mounted on the face plate.These LEDs illuminate for a couple of seconds as part of the power updiagnostic routine. These are tripped by watchdog timer faults,

database errors or through certain other conditions satisfied in thesoftware.

14.6.1CPU Module

CPU Module is the brain of the entire computer system. whichprocesses all incoming locomotive parameters and controlslocomotive responses to derive the operating characteristics. Itcontains the following hardware

32 bit Motorola 68020 16.5 Mhz microprocessor with a math co-processor for enhancing the speed and efficiency of informationprocessing

Motorola 68881 floating point co-processor running at 16.5 M Hz

512 KB flash prom memory storage which can be easilyreprogrammed in the field with the aid of laptop computercommunicating through an RS 232 port or through special modulecalled MMB. While the time required to load a programme fromMMB is approximately 15 seconds, the same through laptopcomputer is 15 minutes. The programme storage can be upgradedto 1 MB.

128 KB static RAM for data storage, which can be upgraded to 1MB

64 K B static dual port RAM for inter processor communication .

6840 Programmable timers which are use for periodic inputs andout puts.

RS232 Serial port with programmable baud rates.

RS422 Serial port with programmable baud rates. One of theseport is dedicated to the display unit.

CPU module plays a very active role in SCR gating sequence as itsends the weak gate signals to the FCD and receives information from thezero cross detection circuit on the FCF so that it knows what phase angleto fire at to achieve desired alternator excitation.

14.6.2Digi tal Input /Out Put (I/O) Modules

Comment [D1]:


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The digital inputs and output to and from EM2000 are handled bythree such modules. Each module has 24 input channels and 26 outputchannels. This module works as an interface between locomotives 74VDC control system and the computers 5 VDC system.

The DIO input channels are either +74 VDC or 0 VDC signalsdepending upon the relay/contactor status, picked up or dropped out. TheDIO output channels, in turn, depend upon the logic built-up, either +74or 0 VDC, so as to pickup or drop out the relay/contactor by supplying thegating power to the field effect transistor.

Multiplexing is a selective monitoring process through which severalinputs may be monitored through the use of only one input channel. Inother words not all inputs need be monitored constantly.

14.6.3Communication Module

All the computers on board i.e. EM2000, Sibas 16, electronic brakecomputer etc. need communication with each other. The two tractioncomputers SIBAS 16 communicates to each other and to EM2000. Thelink carries all sorts of the information which, inter alia, could be dataranging from torque requests, feed backs to contactor requests andacknowledgements to fault annunciation etc.

14.6.4Analogue To Dig ital And Dig ital To Analogue Module

It is responsible for converting analogue input signals to digital signal

for processing the data and digital information from the CPU into ananalogue signal that is required by the receiving device (externalammeters). It has within it -

Differential analogue inputs

Hall effect transducer current inputs

General purpose frequency inputs for period & frequencymeasurements

14.6.5 Memory (Archive Memory) Module

This module holds dynamic locomotive parameters and archive datathat are required to remain intact even in case of power failure. It has one

128 KB battery backed static RAM . which can be upgraded. The amountof data stored with each fault is substantial. For selected faults such asground relay, data is stored from each of the 5 seconds before theoccurrence of the fault.

14.6.6 Panel Mounted Modules

Many other modules, called panel mounted modules, belonging to theEM2000 control are directly mounted to the rear panel of the HVC. Thesemodules are-


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Analogue signal conditioner modules- ASC 300- scales and filters

analogue signals.

Firing control driver - FCD 300 - amplifies SCR gate signals to controlthe CA6 output for main alternator field.

Firing control feedback - FCF 300 - scales three phase companionalternator frequency feedback

Voltage amplifying module- VAM 300- trainline 24 T interface for slowspeed pace setter control ( optional for GT46MAC)

Trainline filter - TLF 300- scales and filters digital data from trainlinesignals.

14.7 Power Supply

EM2000 control system requires different power supply and conditionermodules which are mounted in the Power Chassis. These modulesare-

PSM 300 module for Power supply of +5V DC - the main power supplyfor EM2000

PSM310 module for +12VDC -

PSM 320 module for Power supply of +15VDC - for feed back circuitslike hall effect transducer devices & analogue circuits viz. magneticspeed pickup

PRG300 power regulator is the power conditioner for the PSM modulesand functions properly even with the voltage variation within 20-95

VDC. It regulates the output voltage between 64-77 VDC when theinput voltage is between 25-68VDC. If the input is beyond this range,there is a variation in the output within the acceptable limit.

14.8 Development Of Software

The software for EM2000, or any sophisticated computer system, isdeveloped by EMD in the following steps-

Development of Sales SpecificationFinalization of System SpecificationDevelopment of Software SpecificationActual Software Code WritingSoftware Test

A locomotive characterisation report, which identifies the exact type ofthe equipment used, defines all the functions and indicates the value of all theparameters, is issued by the Product Engineering group. This report formsthe basic locomotive document and the foundation on which the entiresoftware of the locomotive is built up.

14.9 Locomotive Performance & Train Run Simulation


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EMD has developed versatile computer simulation programme for trainrun simulation and offers this service to all its customers on commercial basis.

14.10 Thyristors, GTOs And AC Motor Control

The thyristor offers immense advantages like compactness, highreliability, excellent time response and low loss. An added advantage of usingthyristors in power converters for drive control is the easy manner in whichthey can be adopted for sophisticated feed-back schemes. As a result,microprocessor control of thyristor-drive systems can provide greatoperational flexibility.

GTO thyristor or the gate turn-off thyristor is referred to briefly asGTO. Itis a four-layer silicon semiconductor device and is an improvement

over the normal, slow devices used in line commutated converters intoincreasingly faster devices with better dynamic characteristics by refining thegate geometry.

GTO allows fast turn-off with a negative current impulse by means ofthe gate alone, which is not possible with the conventional thyristor. Thisresults in simplification of the converter circuitry.

A three-phase inverter system with variable voltage and frequencyoutput, is achieved by using GTOs for speed/torque control of 3-phaseasynchronous motor.

14.11 Pulse-Width Modulation

Six load carrying thyristors and six free wheeling diodes are thebasic ingredients of three phase bridge inverter circuit. A DC-link capacitor isadded for stabilising the DC-link voltage and supplying of magnetisingreactive power required for induction motor.

+ + +

+ + +

I N P U T C O N V E R T E R

V O L T. - S O U R C E I N V E R T E R

DC

LIN

K

C AP.

M

3 ~


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PWM INVERTER CIRCUITFIG-7

Amplitude and frequency setting take place solely by the principle ofpulse width modulation (PWM). The max. possible amplitude of the phase-to-phase output voltage Uv depends on the magnitude of the DC link voltageUd such that,

Uv = 0.78 Ud

This method of voltage control of an inverter is known as pulse-widthmodulation.

14.12 Locomotive Cables, Wire Running And Layout

GT46MAC locomotive employs mainly the Exxon cables. The cables used onthis locomotive are classified into following categories:

Category 0 - These are used in the circuits with extremely highpotential requiring increased creepage distances.(DC link cables)

Category 1- These are used in the circuits of high potential and highcurrent levels ( Generator , Traction Motors and Battery Trunk Lines to berouted through cleats)

Category 2 - These are used in the circuits of AC voltage and highcurrent DC voltage (conductors larger than AWG#12, not including tractioncircuit)

Category 3 - These are used in locomotive control logic wiring

(typically 74 V DC including all electro mechanical devices) Category 4 - Low voltage and energy control signal lines ( shielded

multi conductor cables, and signals below 24 V)

Category 5 - Specific conductors requiring independent routing(communication radio antenna cabling, or high energy unfusedconductors)

14.13 Locomotive Cabling:

All the cables which are to be laid out on the underframe are performedwith end lugs, connectors, sockets provided. For this purpose there is aseparate section consisting of the wire measuring and cutting table, endshearing machine for preparing the ends and crimping of the lugs. The

bigger size lugs are made in house using metallic tubes on a lug makingmachine, others are bought out from trade.

The cabling on the underframe is done in the belly up position (in the over-turned position)

The cable layout has been so planned that all the cables are planned torun on only one side of the underframe i.e. on the left side in the belly upposition looking from the short hood side.


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Brackets for the rubber cleats are welded to the underframe before thelaying of cables is started and are located through out the length of theunderframe.

The power cables are laid first followed by the control cables. For thecontrol wires running between EM2000 and Traction Control Cabinet useis made of special channel having EMI protection and runs on the topcorner through out the length of U/frame.

The cleats used are of BUNA-N rubber. Special clamps for smallerdiameter cables are used which have a rubber lining to prevent thedamage of insulation of cable due to vibrations and prevention fromgrounding.

Splicing of the power cable going into the traction motor is done to avoidrunning of large number of cables from TCC and the exposed joints are

covered using heat shrinkable silicon rubber boots. Cutouts on the underframe are already provided for the cables and no oxy

cutting of the underframe is done at all during the cabling stage.

A separate wire running list as per zone, wire category and wire tag isprepared and circulated to the shop to give details of wire running from sourceto destination. The wire running list is derived from the locomotive schematicas soon as the same is ready.

14.14 Electrical Schematics

The schematic of GT46MAC consists of two major parts - EMDschematics and Siemens schematic. The schematic conventions followed byEMD and Siemens are different.

The major equipment covered by the two sections of schematic are asunder-

EMD schematic - EMD manufactured or vendor supplied equipmentviz. alternator - rectifier, locomotive computer, electrical control cabinetsincluding all switches, contactors and relays, auxiliary machines, safety andalarm circuits, third party equipment like radar etc.

Siemens schematic - Siemens manufactured equipment viz. inverterand inverter control equipment, traction computer and traction motors.

The EMD schematic is built around the main block diagram of the

electrical equipment of the locomotive. Theschematic is a representation ofthe hard wiring along with the connection/termination details of the equipment.All the computer/microprocessor modules, which control the operation of thehardware like relays, contactors etc., have been represented as a block. Thelogic used by EMD is not known.

All the electrical sub-assemblies like ECCs, control consoles etc. havebeen allocated a zone identification. This schematic also explains the variouswiring nomenclature used in the EMD schematic. For locating any item, theequipment locator chart provided in the schematic can be used which


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identifies location based on the zone in which the equipment in question lieson the locomotive and schematic sheet no. along with the location on theschematic sheet. Similarly, the circuit for any function like engine coolingcontrol, engine governor control, traction motor bearing temperature probeetc. can be located easily in the schematic by using an alphabetical index. Inaddition, locator charts based on digital & analogue input/output functionsemployed on EM 2000. A chart detailing the location of various switches andcircuit breakers as well as the sequence of operation of main interlock contactof the switches is also provided in the schematic.

The schematic is very versatile and the category, size and specificationof any wire can be read straightaway from the connecting points. In addition,details of all plugs and receptacles are also provided clearly indicating theused & potential free pin numbers. Details of terminal boards are also givenwith internal & external connections with locomotive wire numbers.

The schematic can be divided into three strings of control viz. Battery(i.e. on battery side & past battery knife switch), local control (PA / NA string)& control (

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