INTRODUCTION

Locomotives of India

The locomotives of India presently consist of electric and diesel locomotives. Steam

locomotives are no longer used in India, except in heritage trains. A locomotive is also called

loco or engine. The Bengal Sappers of the Indian Army were the first to run a steam

locomotive in India. The steam locomotive named ‘Thomason’ ran with two wagons for

carrying earth from Roorkee to Piran Kaliyar in 1851, two years before the first passenger

train ran from Bombay to Thane in 1853

Rajdhani Express with WAP-5 broad gauge AC electric locomotive.

A passenger train with WDM-3D broad gauge diesel locomotive.

Classification of Locomotives

In India, locomotives are classified according to their track gauge, motive power, the work they are

suited for and their power or model number. The class name includes this information about the

locomotive. It comprises 4 or 5 letters. The first letter denotes the track gauge. The second letter

denotes their motive power (Diesel or Electric) and the third letter denotes the kind of traffic for which

they are suited (goods, passenger, mixed or shunting). The fourth letter used to denote locomotives'

chronological model number. However, from 2002 a new classification scheme has been adopted.

Under this system, for newer diesel locomotives, the fourth letter will denote

their horsepower range. Electric locomotives don't come under this scheme and even all diesel locos

are not covered. For them this letter denotes their model number as usual.

A locomotive may sometimes have a fifth letter in its name which generally denotes a technical

variant or subclass or subtype. This fifth letter indicates some smaller variation in the basic model or

series, perhaps different motors, or a different manufacturer. With the new scheme for classifying

diesel locomotives (as mentioned above) the fifth item is a letter that further refines the horsepower

indication in 100 hp increments: 'A' for 100 hp, 'B' for 200 hp, 'C' for 300 hp, etc. So in this scheme, a

WDP-3A refers to a 3100 hp loco, while a WDM-3F would be a 3600 hp loco

The first letter (gauge)

W – Indian broad gauge (the "W" Stands for Wide Gauge - 5 ft 6 in)

Y – metre gauge (the "Y" stands for Yard Gauge - 3 ft or 1000mm)

Z – narrow gauge(2 ft 6 in)

N – narrow gauge (toy gauge) (2 ft)

The second letter (motive power)

D – diesel

C – DC electric (can run under DC overhead line only)

A – AC electric (can run under AC overhead line only)

CA – both DC and AC (can run under both AC and DC overhead line); 'CA' is considered a

single letter

B – Battery electric locomotive (rare)

The third letter (job type)

G – goods

P – passenger

M – mixed; both goods and passenger

S – shunting (also known as switching engines or switchers in the USA and some other

countries)

U – electric multiple unit (used to carry commuters in city suburbs)

R – Railcars

History of Howrah Workshop

1. The East Indian Railway Company established a Railway Carriage & Wagon Workshop at Howrah in the year 1863. In the year 1900, it was shifted to its present location at Liluah.The workshop is 114 years old and had celebrated its centenary year in 2000.The workshop is located in the industrial hub of Howrah district, by the side of river Hooghly.It is spread over an area of 2.99 lakh Sq m having a covered area of 1.05 lakh Sq M.The total sanctioned staff strength is 10282 (as on 01.01.14).

2. The workshop was established for undertaking Periodic Overhauling of carriage and wagon stock. At present, the main activity of Liluah workshop is Periodic Overhauling and Intermediate Overhauling of AC & Non-AC Coaches.It is one of the 3 pioneer Workshop on IR to do POH/IOH of LHB Coaches. Shop also undertake POH of Wagon and is the only Shop on ER to give POH of BVZI & BLC Wagon.

3. The existing layout of Liluah Workshop does not provide room for further expansion as is bound on two (North & South) sides by water bodies (North and South tanks), by a municipal road on East and Howrah-Burdwan Mainline on West side. The covered area has virtually reached saturation point. As a result, despite the requirement to expand the volume of activities in Liluah, it is no longer feasible to add covered space.

Indian locomotive class WAP-4

The locomotive was developed, after a previous class WAP-1 was found inadequate to haul the

longer, heavier express trains (24 - 26 coaches) that were becoming the mainstay of the Indian

Railways network. It was introduced in 1994, with a similar bodyshell to the WAP-1 class, but with

Hitachi traction motors developing 5,000 hp (3,700 kW) (5,350 hp or 3,990 kW starting).

Electricals are traditional DC loco type tap changers, driving 6 traction motors arranged in Co-

Co fashion. This locomotive has proved to be highly successful, with over 800 units in service and

more being produced. Newer examples have been fitted with Microprocessor Controlled diagnostics,

Static Converter units (instead of arnos) and roof mounted Dynamic (Rheostatic) Brakes.

The locomotive can be seen in service across the electrified network of Indian Railways and are

homed at 14 sheds (depots).

It was also designed to eliminate the need for bankers.

Design

The loco has a streamlined twin cab carbody design, with top-mounted headlamps. The first 150 or

so units had the headlamp mounted at waist level, with the lights being mounted in a protruding

nacelle. Some earlier locos, especially from the Erode loco shed have the headlamps placed on the

top. Later on the headlamps were placed in a recessed nacelle, and from road # 22579 onward, the

headlamps were moved to the top. Also they have digital notch repeaters.

The loco features higher power rated silicon rectifiers and indigenously-designed 5400 kVA

transformer coupled with Hitachi HS15250 traction motors. Starting power is 5,350 hp (3,990 kW),

with 5,000 hp or 3,700 kW being supplied continuously.

Original units were weighed 120 tonnes, which was brought down to 112 tonnes through the usage

of lighter material.

Some of the WAP-1 and WAP-3 and all the WAP-6 units were rebuilt to WAP-4 specifications after

replacing the bogies & electricals.

It has different underframe for handling larger buffing loads. Some units are fitted with speed

recorders and some changes to control electronics. Some units also have data recorders for energy

consumption. Some are even fitted with windshield washers. Few were provided with signalling

lamps.

Technical variants include WAP-4E which are probably fitted with electronic sensor for sensing loss

in pressure in pipes.

The Hitachi traction motors are the ones used on freight engines. It was a challenge to put these in a

passenger engine due to weight constraints. So the transformer is aluminum foil-wound and

aluminum chequered plates are used for reducing the weight. These traction motors were more

reliable.

1 Main circuit breaker 2 Potential transformer 3 Pantograph 4 Resistor harmonic filter 5 Surge arrestor 6 Roof line

Performance

The class is used to haul the premier Rajdhani & Shatabdi expresses at 140 km/h (87 mph). In trials,

the locomotive has achieved a top speed of 169 km/h (105 mph), though Indian Railways limits its

top speed to 140 km/h (87 mph).

With a 24 coach passenger train, the acceleration time / distances are (*):

110 km/h - 198 seconds (4.8 km)

120 km/h - 260 seconds (7.5 km)

130 km/h - 445 seconds (13.5 km)

Starting Tractive Effort (Te) - 32000 kg/force

(*) Conflicting data observed in practice, further verification required.

If the average weight of ICF coach is 55 tonnes then it can haul the following capacity in tonnes:

ANALYSIS

Description of loco Equipments

Generally an Electric locomiotive consists of two types of equipments

Power circuit equipments

Axulary circuit equipments

Power circuit equipments

Traction Power Circuit ( WAG-9 & WAP-7)

Auxiliary Machines and Equipments in

Electric Locomotives

Electric locos derive tractive effort from Traction Motors which are usually placed in the bogie of the

locomotive. Usually one motor is provided per axle but in some older generation of locos two axles

were driven by a single Traction Motor also.

However apart from Traction Motors, many other motors and equipments are provided in electric

locos. These motors are collectively known as the Auxiliaries. The aim of this article is to provide an

insight into the various Auxiliary Machines provided in the Electric Locos operational on the Indian

Railways.

But to understand the reasons why these auxiliaries are needed, it is necessary to understand the

manner in which the electric locos operate. An important part of the electric loco is the Power Circuit.

A short description of the power circuit of Electric Locos operational on the Indian Railways can

be seen here. The article referred to describes the main components of the Power Circuit of the

Electric Locomotive comprising of the following parts:

1. Transformer (including Tap-Changer)

2. Rectifier

3. Smoothing Reactor

4. Traction Motors

5. Main Starting Resistances (in DC Traction on Dual Power Locos only)

6. Dynamic Braking Resistance Cooling Blower

Transformer Oil Circulating Pump (MPH)

The transformer tank is filled with oil which serves two purposes. It provides enhanced insulation to

the transformer and its surroundings and the oil absorbs the heat generated in the transformer and

takes it away to the Transformer Oil Cooling Radiator. The circulation of this oil is carried out by the

MPH.

A flow valve with an electrical contact is provided in the oil circulating pipe. As long as the oil is

circulating properly, the contacts on the relay remain closed. However, in case the MPH fails or stops

the relay contacts open which in turn trips master auxiliary protection relay Q-118. This trips the main

circuit-breaker(DJ) of the loco. Thus the transformer is protected.

Transformer Oil Cooling Radiator Blower (MVRH) The MPH circulates the transformer oil through a radiator array on top of the transformer. Air is blown

over the radiator by the MVRH. This discharges the heat from the radiator into the atmosphere. A flow

detecting relay is provided in the air-stream of the MVRH. The flow detector is a diaphragm type

device. The flow of air presses the diaphragm which closes an electrical contact. This relay is known as

the QVRH. In case the MVRH blower fails the the QVRH releases and trips the DJ through the relay Q-

118.

The transformer and its cooling equipment. The small vertical motor on top left is the MPH and the horizontal

larger motor in the top centre is the MVRH and behind it is the oil cooling radiator. Click for a larger view.

Auxiliaries of the Rectifier Block (RSI 1 & 2)

Rectifier Cooling Blowers-MVSI-1 and MVSI-2 One blower is provided for each of the rectifier blocks. As rectifiers are semiconductor devices, they

are very sensitive to heat and hence must be cooled continously. The switching sequence of the MVSI

blowers is setup in such a way that unless the blowers are running, traction cannot be achieved. A

detection relay of diaphragm type is also provided in the air stream of these blowers. However, the

detection relay (QVSI-1 & 2)are interlocked with a different relay known as Q-44. This is a much

faster acting relay with a time delay of only 0.6 seconds. Hence the failure of a MVSI blower would trip

the DJ in less than 1 second.

Diaphragm type air-flow sensing relay. Click for a larger view.

Auxiliaries of the Smoothing Reactors (MVSL 1 & 2)

In WAM-4 locos only one MVSL blower is provided for the cooling of the Smoothing Reactors SL 1 & 2.

However in WAG-5 and other locos two blowers namely MVSL 1&2 are provided for each of the SL's.

Their running is "proved*"by the Q-118 relay.

*In railway parlance Proving means to verify whether an equipment or device is working

properly.

Auxiliaries of Traction Motors (MVMT 1 & 2)

In the course of normal operation the traction motors also generate a lot of heat. This heat is

dissipated by two blowers namely MVMT 1 & 2 which force air through a duct into the traction motors

of Bogie-1 namely TM-1, TM-2, TM-3 and Bogie-2 namely TM-4, 5, 6 respectively. The traction motor

cooling blowers require a large quantity of air which is taken from vents in the side-wall of the loco.

Body-side filters are provided to minimise the ingress of dust into the loco. Their running is detected

by Air-Flow sensing relay QVMT 1 & 2 (Pic-2) which in turn give there feed to the Q-118 relay.

MVMT-Traction motor cooling blower motor and impeller covered by a hood. Click for a larger view.

Other Auxiliaries

Air Compressors (MCP 1, MCP-2, MCP-3) Electric locos need compressed at a pressure ranging from 6 kg/cm2 to 10 kg/cm2. Compressed air is

used for the loco's own air brake system as also for the train brakes, for raising the pantograph, for

operating the power switchgear inside the loco such as the power contactors, change-over switches,

windscreen wipers, sanders, etc.

This compressed air is obtained by providing three air compressors, each having a capacity to pump

1000 litres of air per minute. However depending on the current requirement, more than two

compressors are rarely needed.

Main air compressor. Click for a larger view.

Vacuum Pumps (MPV 1 & 2) In locos equipped to haul vacuum braked trains, two vacuum pumps are also provided of which at

least one is running in normal service and sometimes both may have to be run if train brakes are

required to be released in a hurry.

Dynamic Braking resistance Cooling Blower (MVRF) In locos equipped with internal dynamic braking resistances, MVRF blower is provided for cooling the

resistances during braking. While all the Auxiliary machines run on the power supply provided by the

Arno convertor / Static Convertor / Motor-Alternator set, the MVRF blower runs off the supply derived

from the output of the Traction Motor itself and is connected in parallel to the Dynamic Braking

Resistances.

Main Starting Resistance Cooling Blowers (MVMSR) These blowers(four in number)are provided in WCAM-1, WCAM-2, WCAM-3 locos and are used during

DC line working to cool the Main Starting Resistances(MSR). The MSR is used for regulating the

voltage supplied to the Traction Motors during DC line working and carry the whole current of the

traction motors which results in a lot of heat generation which must be continously dissipated. The

working of the MVMSR's is also proved by respective sensing relays(QVMSR's) of the diaphragm type

which in turn are interlocked with the relay Q-118 in the manner described later in this article.

Switching and operational sequence

The auxiliary machines mentioned above are energised as per the requirements in the loco. Some of

them are run continously while some may only be required intermittanly while in rare cases, some

may not be required at all during the whole run of the loco. Also the working sequences of the same

auxiliary machines may differ across different models of locomotives as also in different working

environments. For the purpose of this article, I've described the switching sequences of the WAG-5

loco except for the case of dual power locos such as the WCAM-1, WCAM-2, WCAM-3 which will be

described seperately.

It should be kept in mind that all the above mentioned machines are of large horsepower and hence

consume a lot of power and draw a lot of current from the power supply. In addition when any motor

starts, initially it draws a current which may be up to 3-10 times its normal current. Hence, if all the

motors or even a few motors are started simultaneously, it would cause a tremendous demand on the

power supply in terms of the current drawn. This might also cause the power supply to trip because

the supply is only equipped to deal with the normal running current of the machines and not such a

huge current. To prevent such a situation, the starting of some of the motors is staggered which

prevents heavy load currents from being drawn.

Power Supply

Depending on the locomotive, power for the auxiliary machines is obtained through three different

methods. A separate power supply arrangement is needed because the motors require three phase

supply while the OHE supply is of the single phase type. So the main requirement of the power supply

for the auxiliary machines is for a device which can convert single phase AC into three phase AC. It

becomes a little more complicated for the dual power locomotives such as the WCAM-1, WCAM-2,

WCAM-3.

The three main types of equipments used to supply power to the auxiliaries are discussed below.

Arno Convertor This is a rotary convertor which has a combined set of windings and is used to convert the single

phase supply from the Tertiary winding of the Loco transformer to Three-Phase AC which is fit for use

by the various Auxiliary machines in the loco.

Arno Converter. Click for a larger view.

Schematic diagram of Arno Convertor circuit. Click for a larger view.

The Arno is basically a split-phase induction motor with an additional winding on the stator for the

generating phase. In an induction motor the rotating field of the stator creates a corresponding field in

the rotor squirrel cage too which causes the rotor to start rotating at "slip" speed which is slightly less

than the speed at which the stator field is rotating. However, this rotating field of the rotor is

additionally utilized in the arno to create power in the generating phase winding which gives the three

phase output of the arno convertor. In the stator winding of the arno, the motoring phases carry the

load as well supply currents of the arno in opposite direction which causes a net reduction in the

actual current carried by the windings in the stator but the generating phase carries only the load

current which causes a voltage drop in the generating phase. To counteract this, up to 20% more

turns are provided in the generating phase winding.

Precautions during arno starting

The Arno starts as a split-phase induction motor by inserting a resistance momentarily in the

generating phase winding as shown in the diagram above. This starting resistance must be removed

as the rotor approaches 90% of its normal speed. If this resistance is left in the circuit, it can cause

heating of the generating phase winding and excessive vibrations. If the starting resistance is

removed prematurely it can take longer for the arno to reach synchronous speed. Hence, to maintain

proper timing two methods could be employed-either measure the speed of the arno by attaching a

tacho-generator or measure the output voltage of the generating phase.

The voltage measurement method has been found to be more effective and is used in this system. The

voltage between the generating phase and the neutral of the arno convertor remains at a low value till

just before the arno reaches its synchronous speed when it reaches its full value and is measured by

the relay named QCVAR. It picks up when the voltage rises to near maximum value. The energisation

of the QCVAR causes the starting contactor C-118 to open which disconnects the starting resistance.

The normally open (NO) contacts of the QCVAR are also interlocked with the Q-118 relay. This

interlock is used to ensure that if the QCVAR fails to operate within 5 seconds, the Q-118 interlock

trips the DJ. A bypass switch named HQCVAR is also provided which can be used to bypass the

HQCVAR relay in the Q-118 branch so that DJ tripping does not occur but in such a case the Arno

must be monitored continuously to ensure that its not overheating.

Static Invertor The Arno convertor suffers from various disadvantages chief of which is output voltage imbalance

which can cause heating up of the auxiliary motors, varying output voltage because of the variations

in OHE voltage, problems related to starting of the Arno, etc. To overcome these shortcomings and to

improve loco reliability, the Indian Railways have started providing Static Invertor power supply for

auxiliary machines in locomotives.

The Static Invertor comprises a force commutated rectifier, a DC link and an Invertor which is usually

composed of six IGBT switches.

The Static Invertor broadly works in the following manner:

The supply from the transformer tertiary winding is fed into the rectifier of the Invertor which is force

commutated and is usually composed of IGBTs. The rectified supply is fed into the DC link which is a

large capacitor and is charged by the DC supply. The DC link also has an inductor to suppress the AC

ripple left over from the rectification cycle and harmonics generated by the invertor. Additionally the

DC link maintains the supply to the invertor in case of temporary supply failure and also absorbs

transient voltages generated during switching heavy loads. In some models if the Static Invertor, an

IGBT type switch is provided which is used to switch the DC link in and out of the circuit as per

requirement.

The DC from the rectifier/DC link is converted into three phase AC by the Invertor module by

switching the IGBTs in proper sequence which creates a near sine wave AC displaced by 120 degrees.

Voltage control is achieved by the Pulse Width Control (PWM) method. This ensures that the output

voltage of the Static Invertor is near constant irrespective of the input voltage from the transformer.

Apart from improving the reliability of the power supply system, one of the most important

advantages of the Static Invertor is that it has considerably reduced Auxiliary Motor burnouts due

drastic improvement in the power quality in terms of voltage.

Additionally the Static Invertor also detects earth faults, single phasing and overloading hence these

functions are no longer needed to be monitored by external devices.

An electronic control system is provided which monitors the complete functioning of the Static

Invertor. The control system gives the gate firing impulses to the various IGBTs and also controls the

phase angle of the firing pulse to ensure proper phase sequencing. In addition it monitors the Static

Invertor for internal and external faults.

Motor-Alternator Set (used only in the WCAM-1 and the WCG-2 locos)

Motor-alternator set provided in WCAM-1 locos. The MA set is the green machine to the right. The silver box to the

top left is the FRG (Frequency Regulator). Click for a larger view.

The MA set is used to generate power for the Auxiliary machines in both the AC as well as DC sections

because the Arno cannot run in DC line supply. The MA set comprises of a DC motor coupled to an AC

alternator by a mechanical coupling. When the loco is under AC line supply the DC motor of the MA

Set is fed by the tertiary winding of the transformer via an auxiliary rectifier known as RSI-3. While

running in DC line sections the DC motor of the MA Set is supplied directly by the OHE line supply. The

switching between the AC and DC modes is determined automatically by the position of the Panto

changeover switch ZPT which in turn determines the position of the Change-Over switches.

A stable AC supply output consists of two main parameters namely the frequency and the voltage. The

frequency of the output supply is directly dependent on the speed at which the alternator is running

and the output voltage is dependent on the field excitation voltage of the alternator. Generator speed

tends to fall as the electrical load on the generator increases and vice-versa. To keep the speed of the

alternator near constant a frequency regulator is provided which continously monitors the frequency

and as per requirement controls the speed of the alternator by reducing or increasing the field

excitation of the DC motor. A bypass switch for the frequency regulator is also provided in case the

FRG becomes defective.

Power circuit equipments Roof- equipments

The HT current for feeding the locomotive is taken from the catenary line by means of pantographs.

The locomotive is equipped with two pneumatically controlled pantographs PT1 and PT2.

Each of these two pantographs can be put out of operation and earthed by means of a hand-operated roof bar HPT1 and HPT2.

For ensuring safety of the operators during the maintenance work, to be carried out in the locomotive, a hand-operated earthing switch HOM is provided which makes it possible to earth simultaneously the entire roof line and the HV input terminal of the locomotive after lowering the pantographs. When earthed, the earthing switch HOM cuts off the compressed air supply to the pantographs, locks the electric control handle of the pantographs, release the keys in the key box for opening the HV compartment and the ladder leading to the roof.

Voltage regulating equipment

The main transformer comprises of an auto-transformer with 32 taps (TFWR) and a step-down transformer (TFP) with two separate secondaries.

The primary of the step-down transformer is connected to one of the 32 taps of the auto transformer by means of the 32 step tap changer GR, which is driven by a pneumatic servo-motor.

The passage from one tap of the transformer to another takes place on load.

The main transformer comprises moreover of an auxiliary winding (TFWA) for feeding the auxiliary circuits. The circuits for auxiliaries are connected to 380 V±22.5% V AC supply from terminal al – a0 of the tertiary winding of main transformer. The circuits are protected by capacitors CAPTFWA 1-2 against over voltages, and by 2 RC networks.

The secondary windings of the step-down transformer TFP (a3 - a4, a5 - a6) are protected against excess voltage by means of surge arrestors ETTFP 1-2, condensers CAPTFP and RC networks for each of the two secondaries.

Silicon Rectifiers

Conversation of alternating current supplied by the secondary (a3 - a4, a5 - a6) windings of the main transformer into direct current takes place by means of two silicon rectifiers.

The undulation of the current thus rectified is reduced to a value acceptable for the traction motors by means of two smoothing reactors (SL) to two separate groups of three traction motors. In case of any one silicon rectifier is defective can be cutoff.

Traction motor equipment

The traction motor double reverser Jl-2, is pneumatically controlled and connects the field windings

of the motors in such a way that these carry current in one direction or in the other thus enabling the

locomotive to run in either directions. are used to prevent the ripple components of the current from

passing into the field windings.

The traction/braking switch CTF 1-2 with pneumatic control connects the power circuits of motors for traction or braking.

In traction position all the 6 motors Ml to M6 are supplied by the two silicon rectifiers in two groups of 3 motors each connected in parallel through contactors L-l to L6.

Traction motors are connected in parallel, each rectifier unit catering to three motors.

For electrical braking, the motors are disconnected from the silicon rectifiers and the armatures are connected to the braking resistances by means of the traction braking switch CTF 1-2 . Braking resistances are cooled by blowers MVRF. The field windings of all the traction motors are connected in series and fed by the braking excitation transformer ATFEX and RSI1

THE PROTECTION RELAYS

1 HIGH VOLTAGE OVERLOAD RELAY (QLM)

The relay QLM is fed by means of the current transformer TFILM (250/5 A) which causes the high voltage circuit breaker to trip out, if the current taken in by the main transformer exceed the setting value of the relay (300 A).

2 OVERLOAD RELAYS FOR SILICON RECTIFIERS (QRSI-1 & QRSI-2)

The relays QRSI 1-2 are fed by means of the rectifier current transformer RSILM-1 and 2 (4000/5 A) which cause the high voltage circuit breaker to trip, of the current taken in by the rectifiers exceeds the setting value of the relays (3600 A).

3 BRAKING EXCITATION OVERLOAD RELAY (QE)

The relay QE is fed by means of the excitation current transformer ELM (1000/5A) which causes the braking excitation contactor C-145 to trip out, if the current taken by the excitation winding of the motors exceed the setting value of the relay (900 A).

4 BRAKING OVERLOAD RELAY (QF-1 & QF-2)

The relays of QF 1-2 are connected to the shunts SHF 1-2, which cause the braking excitation contactors C-145 to trip out, if the current taken by braking resistance RF-1 & RF-2 exceeds the setting value of the relays (700 A)

5 MAIN CIRCUITS EARTHING RELAY (QOP 1-2)

In case of failure of insulation of traction power circuit to earth, the battery supply available to the relay trips the relay through the earth and it turn opens the HV circuit breaker DJ.

The switch HQOP 1-2 makes it possible to isolate the relay QOP 1 or 2 and replaces it through a resistance RQOP in order to limit the fault current. With HQOP in OFF it is possible to switch again the circuit breaker DJ in order to bring the locomotive to the shed.

6 TRACTION MOTOR OVER VOLTAGE RELAY (Q20)

Relay Q20 which is connected via resistance RQ20 across rectifier output causes buzzer SON 1-2 to work, if voltage exceeds 865 V. When voltage falls to 740 V, buzzer stops working.

7 NO VOLTAGE RELAY (Q30)

The relay Q30 drops out if the single phase auxiliary winding voltage drops below 215 volts. Its contacts switch off relay Q44, thereby tripping DJ. Relay Q30 is switched on directly via the contacts of the relay Q45 and is fed via resistor RQ30 after the relay Q45 opens/ drops.

8 ARNO STARTING RELAY (QCVAR)

Relay QCVAR has been put across 'W' phase and neutral of Arno to ensure its starting. This cuts out Arno starting contactor Cl18. This is English Electric Relay. It picks up at 155-160 volts AC.

9 BATTERY CHARGER SIGNALING RELAY (QV-61)

This relay which is provided across the battery charger CHBA, indicates the working of the charger. This relay is English Electric make and operates at a voltage of 68-136 V. D.C.

MEASURING INSTRUMENTS IN POWER CIRCUIT

TRACTION MOTOR VOLTMETER (U 1-2)

The meter indicates the voltage applied to traction motor armature during traction. During rheostatic braking also the generating voltage can be read through the meter. It is a moving iron type having range of 0-800 V.

TRACTION MOTOR AMMETER (A 1/1, Al/2 & A 2/1, A2/2)

These ammeters are provided to read the traction motor currents during service. These are moving coil type instruments having a range of 1000-0-1500 Amps. Braking currents can also be read on 0-1000 A range.

AUXILIARY EQUIPMENTS

Voltage stabilizer for headlight (RTPR)

The voltmeter UA-1, UA-2 are fitted in the control desks and have double scale on which the auxiliary voltage and the catenary voltage can be read .

The circuit is protected by fuse CCRTPR. This is meant for maintaining constant voltage for the headlights of the locomotive to ensure that these provide a uniform level of illumination and also to protect the lamps from fusing. It also feeds 24 V supply to the measuring instruments through switch BL1LF and BL2LF. This is also provided with a 16 V tap for dimming the headlight.

TFS

The transformer supplies 115 V AC supply to the system which transmit the position of the tap changer GR to the control desk for indication after stepping down 230 V AC supply.

Static Battery Charger CHBA

The static battery charger is fed from the supply of Arno converter. The unit comprises of a stepdown

transformer, magnetic amplifier and rectification unit. The charger is able to give an output voltage of

110V DC and a load 20 Amps.

Traction Motor:

There are total 6 traction motors provided in WAG-9 / WAP-7 loco. TM 1-2-3 are mounted in bogie-1 and fed from traction converter -1 where as TM 4-5-6 are mounted in bogie -2 and fed from traction converter -2. In case of WAP-5

there are 4 traction motors in which, Traction converter-1 fed to TM-1-2 where as

traction converter-2 fed to TM3-4.

Stator and Rotor of Traction motor

Unlike conventional WAG-5 /7 individual TM cannot be isolated in this loco only a group isolation is possible. For isolation of TM group one rotating switch No. 154 is provided in SB-1, its normal position is ― Norm‖. In WAP-7 & WAG-9 , the traction motor is forced—air cooled and intended for transverse installation in a 3—motor bogie. The power transmission is effected via a spur—wheel gear. In WAP-5 the TM is fully suspended and connected with gear by hurth coupling by which power is transmitted. Traction motor is suspended on axle, by axle cap at one end and on link at another end.

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Technical Data Of Traction Motor

Auxiliary Power Circuit

Conclusion Attending this 14 days training in electric traction Howrah division eastern railway, we conclude that in this overall training, I put my greatest effort to understand & explore more & more about the loco and electric traction. But the loco is such a complex machine which has so many function & components which need so much time to understand. But I tried my best to utilize this short span of time to make out the valuable knowledge about the loco and electric traction.

ACKNOWLEDGEMENT I am thankful to the Organization ―LOCO SHED HOWRAH‖ For providing necessary facility to carry out my training successfully .It is our duty to record our sincere thanks and gratitude towards the institute staff, who helped us bringing this project to its present form .The valuable guidance and interest taken by them has been a motivator and source of inspiration for me to carry out the necessary proceedings for the project to be completed successfully. Also ,we are extremely thankful to all the employees of ― ELECTRIC LOCO SHED(HOWRAH). We are thankful to them ,all of them………

Sr.DEE/TRS/NWH . Sir M.K.Sinha Sr.SE(M)/TRS/ELS- Sri S.Bandyopadhyay ELS- Sri A.K.Mukharjee

E-1 Section-in-charge-Sir B.C.Pal E-2 Section-in-charge-Sir M.K.Das E-3 Section-in-charge-Sir S.Das E-4 Section-in-charge-Sir S.K.Yadan M-3 Section-in-charge-Sir I.Nag

LIST OF REFERENCES LITERATURE CITED:

Traction Rolling Stock – Maintenance by Institution of Railway Electrical Engineers (IREE)

HAND BOOK ON 3-PHASE ELECTRIC LOCO

WEB HELP :

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