8 WHEELER DIESEL ELECRIC TOWER CAR WITH UNDERSLUNG TRANSMISSION. OPERATING & MAINTENANCE MANUAL (2019)

CIRCUIT DESCRIPTION

current shall be known from Battery Charging Ammeters provided on the Control Cubicle (Cab-1). 24 VDC

Battery supply is used for cranking the Diesel Engines.

3.3 CIRCUIT DESCRIPTION

Preparing Diesel Electric Tower Car/US for operation: -

All the MCBs (110 VDC & 24 VDC) are in ON position.

Engine Control Switch Mounted on Driver’s Desk is in IDLE position while Diesel Engine(s)

starting.

Motor Cutout switches mounted on control cubicle cabin-1 is in “NORMAL” Position. Depending

on the faulty motor, position of the switch is changed to appropriate condition to isolate the faulty

Traction Motor.

Local/Remote switches mounted on the Control Cubicle-1 are in “Remote” Position when the Diesel

Engine is started from driver’s desk. It is in “Local” position when the Diesel Engine is started

locally from the push button station mounted under the frame.

All the by-pass switches are in OFF position.

Battery Isolating Switch - BIS (110 Volts DC) is in “AA1&2 in CKT” position and BIS (24 Volts

DC) is in ON position.

Driver’s control switch mounted on Driver’s Desk is in “ON” position.

Hydraulic oil level switch (HOLS1 [2]) is in close condition, if the oil level is above the specified

limit.

Diesel Engine mounted water temperature switch (TS11 [12]) is in close condition, if the water

temperature is below set position.

Diesel Engine mounted lubricating oil pressure switch (PS11 [12]) is in open condition before

cranking of Diesel Engine.

Diesel Engine mounted overspeed switch (SS11 [12]) is in close condition, if the speed of the Diesel

Engine is below overspeed set speed.

Cooling water level switch (CWLS1 [2]) is in close condition, if the water level is above set level.

Ensure the Master Controller Reverse handle in “OFF” position and Main Handle position is in ‘0’

position.

MAINTENANCE MANUAL FOR DETC-US

CIRCUIT DESCRIPTION

3.4 CRANKING OF DIESEL ENGINE

Before starting the Diesel Engine, circuit needs to be reset, which bypass the safety system during starting.

The same is accomplished using “Ready to Start” spring loaded switch mounted on the Driver's Desk.

During starting Engine Trip Relay FC21 (FC22) is energised and “Engine-1 (2) Trip” & “Engine-1 (2) OFF”

indications glow. As soon as the switch is operated, Relays R11 (R12), R21 (R22), R41 (R42), R51 (R52)

and R61 (R62) are energised and cut-off supply to Engine Trip Relay FC21 (FC22) & both the indications go

off. Now the circuit is set for Diesel Engine cranking. Press “ON” the Diesel Engine-1 ON” spring loaded

switch mounted on the Driver's Desk. As soon as the contacts of the “Diesel Engine ON” switch is closed,

Engine-1 ON relay S11 (12) get energised though wire no 1654 (1655). Contact of S11 (12) inturn operates

Remote ON/OFF Relay R91 (R92) through wire 225 (226). As soon as the R91 (R92) is energised, 24 VDC

supply is available to timers TR11 (12) & TR21 (22), Idling solenoid valve & hour meter from 209 (210)

through Local / Remote Switch & Diesel Engine ON relay NO Contact. At the same time wire no 213 (214)

is energised from 209 (210) through Engine ON relay contact and supply is available to magnetic switch

provided on the Diesel Engine (wire no 215/216). As soon as the magnetic switch is energised, supply is fed

to starting motor and allows Diesel Engine to start. If the Diesel Engine is not started for set time - say 6 sec

(set value of timer TR11 (12]), the circuit will break and disconnect supply to magnetic switch. During the

Diesel Engine cranking period, lubricating oil pressure switch is bypassed by Timer 21 (22) contact. The

timer is set at approximately 8 sec. (slightly more than the engine cranking time).

3.5 SPEED CONTROL OF DIESEL ENGINE(s)

As Diesel Engine starts running from 0 RPM, speed sensors provided on the Diesel Engine develops

frequency signal and give feedback to Speed & Load Control System (LCC-107B) through wire nos. 21A

(21B) & 22A (22B). Depending up on the speed setting (Notch), LCC-107B controls the speed of the Diesel

Engine. LCC-107B starts pumping current through wire nos. 31A (31B) & 32A (32B) to Actuator provided

on the Diesel Engine till its speed reaches its set value. Once its speed is reached to set value, LCC-107B

maintains the same actuator current.

Switch ON the “CONTROL” provided on the Driver's Desk. This allows wire no. 1602 to get supply &

“CONTROL ON” indication appears. Move the Master Controller Reverse Handle to either Forward or

Reverse direction & Main Handle to Notch 1 in depressed deadman condition. There is no change in Diesel

Engine(s) speed. Move the Master Controller Main Handle to notch 2. Diesel Engine(s) speed changes to

approximately 1000 RPM. Move the Master Controller Main Handle to higher notches. Corresponding

MAINTENANCE MANUAL FOR DETC-US

CIRCUIT DESCRIPTION

speeds are 1200 RPM at 3^rd Notch, 1300 RPM at 4^th Notch, 1400 RPM at 5^th Notch, 1500 RPM at 6^th Notch,

1650 RPM at 7^th Notch & 1800 RPM at 8^th Notch. Depending upon the speed setting / Notch of the Master

Controller, LCC-107B(s) changes the actuator current of Diesel Engine(s).

3.6 TRACTION ALTERNATOR EXCITATION CONTROL

Change the Engine Control Switch to “RUN” position. Ensure that Master Controller Reverse Handle is in

either Forward or Reverse direction & Main Handle is in ‘0’ position with pressed deadman condition.

Switch ON the “EXC ON” switch provided in the Driver's Control Switch Box. This operation set the

control circuit for excitation. Move the Master Controller Main Handle to Notch ‘1’ position with pressed

deadman condition. As soon as the Main Handle moves to Notch 1, LCC-107B (s) get 1^st notch speed

through coded signals. Meanwhile, wire no. 3 get supply through Master Controller, Excitation Control

Relay ECR1 (2) get energised and “Excitation-1 (2) - ON” indication appears in LED indication panel. This

relay opens the reset voltage 24 VDC between LCC-107B terminals 13 & 14 through wires 203E (203F) &

299A (299B). As soon as the reset voltage is released, the excitation current starts build up from terminals 23

& 24 of LCC-107B(s). Within few seconds it reaches to its maximum to match the Diesel Engine output

power (Gross power - Power Consumed by Auxiliaries). Move the Master Controller Main Handle to Notch

2. As soon as the Master Controller Main Handle is moved to 2^nd notch, logic signals through wire nos. 4,5,6

& 7 changes the Diesel Engine speed using LCC-107B to 2^nd notch speed i.e. 1000 RPM and excitation

changes to get the maximum output power to match with Diesel Engine output. Depending upon the V-I

characteristics (Load Conditions) of the Traction Alternator, excitation current varies through wire nos.

1901A (1901B) & 2101A (2101B) at fixed notch. External Resistance 12 Ω keeps the Excitation current

always below 10 Amps. However, the maximum Excitation current required for Traction Alternator is less

than 6 Amps. Same procedure is applicable for higher notches also.

3.7 HEALTHY & FAULT INDICATIONS:

TRACTION CONTROL SUPPLY ON (GREEN): This is a healthy indication of system. When the

“Control” Switch provided on the Driver’s Control Switch Box of Driver's Desk is in ON position, wire no

1602 gets supply and the indication glows. If this switch is in OFF condition, Diesel Engine speed control &

Traction Alternator excitation control are not possible.

MAINTENANCE MANUAL FOR DETC-US

CIRCUIT DESCRIPTION

ENGINE-1 ON (GREEN): This is a healthy indication of Diesel Engine-1. When the “Diesel Engine-1 ON”

spring loaded switch is operated i.e. Diesel Engine-1 cranking operation is performed, Relay S11 energised

through wire no.1654 & 1664 and will remain in energised condition. When the relay S11 is in energised

position, wire no. 1811 gets supply through its NO contact and hence the indication glows. In case of any

protection circuit operates, this relay de-energises and this indication goes off.

ENGINE-2 ON (GREEN): This is a healthy indication of Diesel Engine-2. When the “Diesel Engine-2 ON”

spring loaded switch is operated i.e. Diesel Engine-2 cranking operation is performed, Relay S12 energised

through wire no.1655 & 1665 and will remain in energised condition. When the relay S12 is in energised

position, wire no. 1809 gets supply through its NO contact and hence the indication glows. In case of any

protection circuit operates, this relay de-energises and this indication goes off.

ENGINE-1 TRIP (RED): This is a fault indication of Diesel Engine-1. This indication glows in any of the

following conditions.

a. Hydraulic Oil Level

LOW

(Normal Hydraulic oil Level is lower than the specified limit)

b. Cooling Water Level

LOW

(Normal Water Level is lower than the specified limit)

c. Lubricating Oil Pressure

LOW

(Normal Lubricating Oil pressure is lower then 10 PSI.

d. Cooling Water Temperature

HIGH

(Normal Cooling Water temperature is more than 95°C)

Hydraulic Oil Level & Water Level of Diesel Engine-1 is monitored by R21 & R61 Relays respectively.

Similarly, Cooling Water Temperature & Lubricating Oil Pressure is monitored by R11 & R41 Relays

respectively. Any of these operations goes wrong respective relay de-energises and which inturn energises

Engine Trip Relay FC21. When FC21 is energised, wire no. 1807 gets supply through one of its contacts and

“Engine -1Trip” indication glows.

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CIRCUIT DESCRIPTION

ENGINE-2 TRIP (RED): This is a fault indication of Diesel Engine-2. This indication glows in any of the

following conditions.

a. Hydraulic Oil Level

LOW

(Normal Hydraulic oil Level is lower than the specified limit)

b. Cooling Water Level

LOW

(Normal Water Level is lower than the specified limit)

c. Lubricating Oil Pressure

LOW

(Normal Lubricating Oil pressure is lower then 10 PSI.

d. Cooling Water Temperature

HIGH

(Normal Cooling Water temperature is more than 95°C)

Hydraulic Oil Level & Water Level of Diesel Engine-2 is monitored by R22 & R62 Relays respectively.

Similarly, Cooling Water Temperature & Lubricating Oil Pressure is monitored by R12 & R42 Relays

respectively. Any of these operations goes wrong respective relay de-energises and which inturn energises

Engine Trip Relay FC22. When FC22 is energised, wire no. 1673 gets supply through one of its contacts and

“Engine -2Trip” indication glows. Under these circumstances, Diesel Engine shuts down.

MOTOR EARTH FAULT (AMBER): In case power circuit is grounded due to any reason, during

operation it causes Ground Fault Relay (GFR) to energise through wire no E. When the GFR is energised,

wire no. 1624 gets supply through one of its contacts, leaving an indication “TRACTION MOTOR EARTH

FAULT”. Once the GFR is energised, it is mechanically latched. Pressing reset button provided with the

GFR resets mechanical latching.

PARKING BRAKE APPLIED (RED): When the parking brake is applied, wire no 1677 energised through

parking brake governor and “PARKING BRAKE APPLIED” Indication glows.

ALTERNATOR-1 EXCITATION ON (GREEN): This is a healthy indication of system, which shows

Traction Alternator-1 excitation is ON. As soon as the Master Controller Main Handle is moved from IDLE

to Notch 1, depending upon the Reverse Handle position, either wire no.1 (Forward) or wire no. 2 (Reverse)

is energised. These wires inturn feed wire nos. 102A & 109A through reverser interlock, Equipment

Governor, Brake Pressure Control Governor and Parking Brake Governors and energise E.P.Contactors LC1

& LC3 mounted inside the Motor Switch Group Cubicle. As soon as these contactors energised, supply is fed

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CIRCUIT DESCRIPTION

to wire no 1614A and energise Excitation-1 ON Relay ECR1. The moment the Relay ECR1 is energised,

indication glows and excitation starts building up from LCC-107B1.

ALTERNATOR-2 EXCITATION ON (GREEN): This is a healthy indication of system, which shows

Traction Alternator-2 excitation is ON. As soon as the Master Controller Main Handle is moved from IDLE

to Notch 1, depending upon the Reverse Handle position, either wire no.1 (Forward) or wire no. 2 (Reverse)

is energised. These wires inturn feed wire nos. 102A & 109B through reverser interlock, Equipment

Governor, Brake Pressure Control Governor and Parking Brake Governors and energise E.P.Contactors LC2

& LC4 mounted inside the Motor Switch Group Cubicle. As soon as these contactors energised, supply is fed

to wire no 1614B and energise Excitation-2 ON Relay ECR2. The moment the Relay ECR2 is energised,

indication glows and excitation starts building up from LCC-107B2.

HIGH COOLING WATER TEMPERATURE (HCWT) - DIESEL ENGINE 1: This is a fault

indication of Diesel Engine-1. When the Diesel Engine-1 cooling water temperature goes high (more than

the specified limit), the temperature switch provided on the Diesel Engine opens and de-energise the Cooling

Water Temperature monitoring Relay R11 through wire no 235. As a result of this, wire no. 4030A gets

supply through one of the relay contacts, leaving indication “HCWT ENG-1” on the Indication Panel.

HIGH COOLING WATER TEMPERATURE (HCWT) - DIESEL ENGINE 2: This is a fault

indication of Diesel Engine-2. When the Diesel Engine-2 cooling water temperature goes high (more than

the specified limit), the temperature switch provided on the Diesel Engine opens and de-energise the Cooling

Water Temperature monitoring Relay R12 through wire no 236. As a result of this, wire no. 4030B gets

supply through one of the relay contacts, leaving indication “HCWT ENG-2” on the Indication Panel.

AUXILIARY ALTERNATOR-1 FAILURE (RED): Before cranking the Diesel Engine-1, “AUXILIARY

ALTERNATOR-1 FAILURE” indication appears on the LED indication panel (through wire no 1683A)

provided on the Driver's Desk, as no supply is being generated by Auxiliary Alternator-1. As soon as the

Diesel Engine-1 is cranked, Auxiliary Alternator-1 starts generating power and Auxiliary Alternator proving

Relay AAPR1 energised through wire no 301 & 303. This relay AAPR1 is always in energised position.

When the relay is energised, the indication through its NC contact disappears. When the Auxiliary Alternator

- 1 stops generating power on account of a defect in the Auxiliary Alternator - 1 and/or Rectifier and

Regulator, the AAPR1 relay de-energises and Auxiliary Alternator - 1 Failure Indication appears in LED

indication panel.

AUXILIARY ALTERNATOR-2 FAILURE (RED): Before cranking the Diesel Engine-1, “AUXILIARY

ALTERNATOR-2 FAILURE” indication appears on the LED indication panel (through wire no 1683B)

provided on the Driver's Desk, as no supply is being generated by Auxiliary Alternator-1. As soon as the

Diesel Engine-2 is cranked, Auxiliary Alternator-2 starts generating power and Auxiliary Alternator proving

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CIRCUIT DESCRIPTION

Relay AAPR2 energised through wire no 302 & 304. This relay AAPR2 is always in energised position.

When the relay is energised, the indication through its NC contact disappears. When the Auxiliary Alternator

- 2 stops generating power on account of a defect in the Auxiliary Alternator - 2 and/or Rectifier and

Regulator, the AAPR2 relay de-energises and Auxiliary Alternator - 2 Failure Indication appears in LED

indication panel.

RECTIFIER FUSE FAILURE - 1 (AMBER): In case of any one-fuse failure in Power Rectifier-1, Relay

RL1 energises through wire no. 4020. Through one of its contacts, wire no.1612A energised leaving

indication “RECT. FUSE FAILURE-1”. In case, failure of three different phase-fuses in three different

bridges in the same rectifier panel, the same is considered as Single Bridge failure. In this case also “RECT.

FUSE FAILURE” indication glows.

RECTIFIER FUSE FAILURE - 2 (AMBER): In case of any one-fuse failure in Power Rectifier-2, Relay

RL1 energises through wire no. 4020. Through one of its contacts, wire no.1612B energised leaving

indication “RECT. FUSE FAILURE-2”. In case, failure of three different phase-fuses in three different

bridges in the same rectifier panel, the same is considered as Single Bridge failure. In this case also “RECT.

FUSE FAILURE” indication glows.

RECTIFIER -1 COOLING FAN FAILURE (RED): It is a fault indication of Power Rectifier-1. Before

the Diesel Engine-1 is not cranked this indication “RECT-1 COOLING FAN FAIL” glows, as there is no

supply available to Blower Motor provided inside the Power Rectifier-1. As soon as power is available to

cooling fan motor, blower starts working and pressure switch provided inside the cubicle actuates and

through wire no.1642A Relay RCFR1 energised. Instantly, the indication goes-off. In case Air pressure

switch provided in Rectifier Cubicle-1 fails, Relay RCFR1 will not energise and Rectifier-1 cooling fan

failure indication appears in the LED indication panel.

RECTIFIER -2 COOLING FAN FAILURE (RED): It is a fault indication of Power Rectifier-2. Before

the Diesel Engine-2 is not cranked this indication “RECT-2 COOLING FAN FAIL” glows, as there is no

supply available to Blower Motor provided inside the Power Rectifier-2. As soon as power is available to

cooling fan motor, blower starts working and pressure switch provided inside the cubicle actuates and

through wire no.1642B Relay RCFR2 energised. Instantly, the indication goes-off. In case Air pressure

switch provided in Rectifier Cubicle-2 fails, Relay RCFR2 will not energise and Rectifier-2 cooling fan

failure indication appears in the LED indication panel.

GOVERNOR-1 SUPPLY FAILURE (RED): This is a fault indication of the system. During normal

working conditions, relay ER1 is energised through wire no 1612 & 1612A and there is no indication “GOV-

1 SPLY FAIL” on the indication panel. Either excitation ON/OFF switch is in OFF condition or Engine

Control Switch is in IDLE position, the Relay ER1 is De-energised. Once the relay ER1 is de-energised, the

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CIRCUIT DESCRIPTION

indication glows on the panel. If GOV-1 SPLY FAIL occurs, excitation of Traction Alternator-1 is not

possible.

GOVERNOR-2 SUPPLY FAILURE (RED): This is a fault indication of the system. During normal

working conditions, relay ER2 is energised through wire no 1612 & 1612B and there is no indication “GOV-

2 SPLY FAIL” on the indication panel. Either excitation ON/OFF switch is in OFF condition or Engine

Control Switch is in IDLE position, the Relay ER1 is De-energised. Once the relay ER2 is de-energised, the

indication glows on the panel. If GOV-2 SPLY FAIL occurs, excitation of Traction Alternator-2 is not

possible.

TRACTION MOTOR OVERLOAD (AMBER): Due to any reason any of the Traction Motor overloads

i.e. Traction Motor current is more than 600 Amps, corresponding Traction Motor overload relay energised,

leaving an indication “TR. MOTOR OVERLOAD” on the indication panel. In case of Traction Motor

overload, supply to traction is cut-off by isolating motor contactors on the Motor Switch Group Cubicle. At

the same time, excitation of respective Traction Alternator (In case of Traction Motor 1 or 3 overload,

Traction Alternator -1 excitation cut-off & in case of Traction Motor 2 or 4 overload, Traction Alternator -2

excitation cut-off) is cut-off. To reset the overloaded traction motor circuit, press the “Traction Motor

overload reset” spring loaded switch provided on the Driver’s Control Switch Box. This operation is possible

only when the Master Controller’s Main Handle is in ‘0’ position.

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NOTES

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MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

CHAPETR V

TRACTION ALTERNATOR

1. INTRODUCTION

This Manual comprises chapters, covering `Description', `Insulation',

`operation' and

‘maintenance’ of

alternator. Alternator has been designed and built in accordance with the generally accepted engineering

practices of Indian Railways Loco/DEMU Sheds. In case of improper installation or improper operation or

improper maintenance, machine gives rise to potential dangers which may cause serious personal injuries or

damage.

While designing this Traction alternator, aspects of user-friendly maintenance and easy manufacture were

kept in mind. Technical data have been laid down for the machines in accordance with the specifications.

It is assumed that the planning and execution of mechanical/ electrical installation, transportation, erection

/commissioning and maintenance will be carried out under the supervision of qualified personnel.

In the case of product maintenance / installation / erection / commissioning, it is advisable to take assistance

or services of the competent CG service centres or inform CG works for the assistance.

The direction of rotation is determined from the bearing end of the machine, it is a single bearing machine,

directly coupled with Diesel engine on one side and supported on ball bearing on the other side.

1.1 TECHNICAL DATA

C1009A1 AC Alternators is a Salient pole, revolving field, brush-less, self ventilated & single bearing

Traction machine. This AC generator is available with SEPARATELY EXCITED SYSTEM (with unique

LCC 107B governor of Governors America Corporation).

Description Make & type

CG, C1009A1

Drive-Details of arrangement

Direct coupled through flex plates

of bearing and coupling

No. of poles, phases & connections

8 poles, 3 phase, Star

Maximum permissible design speed

2250 rpm

One hour rating

544 A, 450 V, 245 kW at 1800 RPM

Continuous rating

• High voltage

345 A, 666 V, 230 kW at 1800 RPM

• Low voltage

718 A, 320 V, 230 kW at 1800 RPM

Class and type of insulation

• Stator

Class H

• Rotor

Class H

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Resistance at 20 °C

• Rotor winding

0.74

Ohms

• Stator winding

0.0089

Ohms

(Per phase)

• Resistance per phase exciter rotor

44 mill ohms at 20 °C

• Resistance for exciter stator

7.2 ohms at 20 °C.

Details of bearings

Single Ball bearing

SKF - 6317 C/3

Grease-type,

HP LITHON-3

Capacity

250 GMs

Interval for regreasing

6 months

Repack the grease

2 years

grease requirement in new

210 Gm

Shaft bearing seating diameter

85 mm

Min. permissible radial clearance

0.03 to 0.13 mm

Mountings-Details

Directly coupled to engine

Weight

Traction Alternator

1385 kgs

Fan

kgs

Rotor

605

kgs

Air Filter Assembly

kgs

1.2 IMPORTANT HARDWARES

Bolting place

Size

Quantity

Type

Alternator mounting with main

M24 x 70 lg. P12.9

16 nos.

Socket head

bracket

Flexible coupling with rotor

M20 x 50 lg. P10.9

08 nos

Hex. Hd bolt

shaft

Alternator mounting with

M16 x 70 lg. P12.9

16nos.

Socket head

engine adopter

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2. SALIENT FEATURES OF ALTERNATOR

C1009A1 AC generator is a Salient pole type, revolving field Brush-less type alternator. These AC

generators are available in a SEPARATELY EXCITED SYSTEM (with unique LCC107B of GAC,

Governors America Corporation).

The insulation system of the stator coils has been improved for higher voltage operation of the high-powered

D.E.M.U., D.E.T.C. & shunter. The traction alternator C1009A1 is capable of operation at a top unloading

voltage of 750V DC continuously.

This alternator is especially design for Indian Railways by CG. The class 200 Insulation System with

Polyesterimide Resin provides best protection against moisture, sand, salt, humidity and corrosive

atmosphere ensuring trouble free operations under the most demanding conditions.

Transient voltage dips are lower.

Liberally rated diodes have been used in rotating rectifier assembly to ensure high product reliability

specifically for rotating application.

The rotating diodes are protected by a surge suppresser, which has the ability to chop the transients from

1600 volts to less than 450 volts.

For D.E.T.C. /U.S. power requirement is maintained constant at different notches.

Voltage X current = constant

Depending upon the load requirement, Constant & rated powers have been achieved through excitation,

which have been controlled with the help governor LCC 107B, which is a special feature of D.E.T.C. /U.S.

Depending upon the load requirements of the multiple unit, Governor provides current input to exciter stator,

which induces power in exciter armature, which then rectified by diode wheel (rotating rectifier) and is fed

into main rotating field, ultimately responsible for the power output of alternator.

The diesel engine in the present case has a gross HP of 340 and input to traction is 310 HP at 38 °C of

ambient and at a speed of 1800 RPM. The higher voltage capability of traction alternator enables the

locomotive to be operated at full field of traction motors. AC Generator armature winding is housed in Stator

and field Winding is placed on Rotor. Brush-less construction of rotating rectifier gives the required amount

of excitation to the rotating field.

The excitation circuit is designed to ensure that the excitation current does not exceed by 6 Amps at any

operating point.

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TRACTION ALTERNATOR

3. ALTERNATOR CONSTRUCTION

3.1 STATOR

Stator consists of stator frame, stator core, armature windings & terminal box.

3.1.1 STATOR FRAME

Stator frame along with terminal box is a fabricated structure using mild steel plate. It is designed to ensure

correct distribution of airflow over the Stator core and windings.

Stator Frame

3.1.2 STATOR CORE

In stator core, Stampings stack is supported with mild steel end plates at both ends & reinforced with landing

bars, which are welded with complete stack & both end plates. Stampings are made of silicon steel with C6

coating for proper welding of stack. These punching are oriented to 90° length one fourth resulting in better

magnetic properties.

Stator core with winding

3.1.3 ARAMTURE WINDINGS

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Winding is designed for 8 pole, 3 phase, double layer diamond winding star connected, housed in a open slots,

single turn ( made up of single conductor having no laminations.)

The Connections are made to the phase rings by gas brazing and phase connectors are taken to the terminal

box by means of BUS BAR. The phase rings are properly insulated between line to line and live to earth

parts.

Armature coils are made from polyesterimde enamelled glass lapped Conductor for class 200 suitable for

VPI formed on special formers.

Overhang is properly tied up with the help of resiglass tape to the epoxy bracing ring so that the electrical

and severe mechanical stress in case of any abnormal event can be resisted by the windings. 5th and 7th

harmonics are mitigated by a 60° winding distribution and should not normally be the major target for

reduction by pitching.

Stator Coil

3.2 WOUND ROTOR ASSEMBLY

Rotor consists of shaft, 8 rotor field coils (4 north polarity + 4 south polarity), diode assy, exciter armature.

The rotor is wet wound for eight poles using epoxy compound and properly interlined to have better

resistance to centrifugal force, then locked with support block to have proper locking. The rotor field coils

are vacuum pressure impregnated with solventless resin of class 200.

Wound Rotor Assembly

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3.2.1 ROTOR HUB:

The shaft is made of forged medium-grade carbon steel IS: 2004 CLASS IV. The shaft is liberally designed

for overload conditions. The rotor shaft is forged and ultrasonically tested to give greater reliability in

performance.

Rotor Hub

3.2.2 ROTOR FIELD COILS

Main field pole is built up of high quality, low silicon, steel sheets, oriented to 180° after every one-fourth

length for better grain orientation and better magnetic properties.

Rotor Pole Brick

For forming the rotor field coil, main field pole is directly wound with rectangular copper conductor by wet

winding process using epoxy compound , which gives better insulation properties and mechanical strength.

The coils are formed by winding directly over the pole body to give better rigidity in service and this also

minimises the loosening of poles in service. While assembling the wound poles utmost care is taken during

the production stage. Field coils are fastened to shaft with high tensile steel bolts with specified torque and

locked through tack weld in position.

The coil to coil strap connectors are individually insulated and brazed to the coil leads. The connectors are

held and braced to support plate of diode wheel several layers of Resi-glass tape is applied on the connectors

(live surface) and cured fully to form a rigid connection.

The fully assembled rotor with field coils and connections is subjected to painting with anti-tracking

insulating paint to avoid trapping of moisture and improved electrical properties.

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3.3 END FRAME:

End frame is fabricated from thick steel plate construction, Spigot to the stator frame and is fixed by easily

assessable high tensile screws. The end frame supports the exciter winding and bearing assembly. It is so

designed to facilitate the easy accessibility of diode wheel for Maintenance.

End Frame

3.4 ROTOR FAN

The rotor fan is manufactured with special Aluminium alloy. Special care is taken to ensure that the fan is

free from any sort of casting defects. All the fans undergo thorough dye penetration and radiographic testing

for highlighting any surface or sub surface defects.

Rotor Fan

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TRACTION ALTERNATOR

3.5 TERMINAL BOX

This alternator stator is having internally 3 phase star connection, brought to the terminal box bus bars.

Phase bus bars are brazed with phase rings, which are supported on the main frame & properly insulated

from earth. The phase bus bars coming out of the frame are properly supported on steel cleats with Resi-

glass tape to minimise the cable tension. Other end of phase cables is fixed on insulating rod through plated

hardware to maintain minimum air gap (creepage) between live to live & live to earth parts. Single holed

Lugs are provided for output power cable connection. RTD terminals have been terminated at elex elements

supported inside the same terminal box.

3.6 DIODE WHEEL ASSEMBLY

Diode wheel assembly is made up of solid iron plate in which insulation discs are bonded together with resin.

Heat sink are specially designed for speed up to 2500rpm. The rotating diodes are protected by a metal

oxide varistor against voltage surges arising due to fault conditions on load side. Diodes are suitable upto

PIV of 1600 volts, and specially designed for high

`g’ application, 3 positive and 3 negative diodes of

Ruttonsha no.

150LMR is used. Each heat sink is specially designed to accommodate one bridge arm and

output is fed into a common copper connector for all the arms to the rotating field.

Details of rotating rectifier

• Mounted on the same rotor shaft of alternator.

• Support plate is made up of mild steel. Its function is clear form the name given to it

• Heat sink is for carrying out the heat generated in the diodes during their operation

3.7 BEARING ARRANGEMENT

The bearing arrangement consists of inner bearing cap, shrink ring, ball bearing, distance collar, outer bearing

cap. Assembly stages of these parts are as shown in fig. All these bearing components are made of forged

carbon steel as per IS: 2004 class 3 & 4. Self-locating, sealed bearing arrangement has been designed to have

better circulation of grease during service. Grease inlet pipe along with grease nipple (1/4 inch BSP) have

been provide in outer bearing cover for topping up grease during routine maintenance

Bearing Assembly

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

4. MAINTENANCE SCHEDULE

At the outset, it may be emphasised that the routine maintenance of Traction Alternator is much simpler due

to the absence of Commutator and its brush-less arrangement.

Routine maintenance of Traction Alternator therefore, mainly includes periodic cleaning and inspection of

the machine.

It is recommended that the period of inspection should be more frequent in the initial period of service, and

schedule can be subsequently relaxed based on experience. The periodic maintenance schedule chart

accompanied with this manual should be filled and should be periodically sent back to the manufacturer.

4.1 CLEANING

Clean all the dust and dirt from the exterior of the Alternator, taking special care at the areas around air

opening and inspection covers. Air Inlet cover is removed from the alternator by taking out the M12 hex

head screw. Then only the air inlet cover can be removed and it is advisable to take care for withdrawal of

small M6 screw while opening the assembly. Air inlet net to be cleaned only with kerosene or and other

solvent. Dirt & dust of the alternator is to be cleaned by vaccum cleaner. In absence of vacuum cleaner, dry

compressed air is to be used for cleaning. During cleaning it is to be ensured that dust is blown out of

alternator or air inlet duct whenever compressed air has been applied for cleaning.

Wipe the dust over the diode and insulation disc and approachable parts of the rotor field coils and

connections. Best way of cleaning is to moist a clean lint free cloth with solvent for wiping. Recommended

cleaning solvents are given in Table.

While cleaning, look for any defects, hot spots or abnormalities, for taking corrective action consult with

manufacturer.

4.2 PERIODIC INSPECTION

Periodic inspection should be carried out after thorough cleaning and following points should be given

special attention.

Inspect the diode wheel for any damage of knots of resi-glass and cable holdings. Use glass chord of dia. 1.0

to do the needful as per the perception of operating personal. This is only a temporary solution.

Check machine exciter for any collection of grease leakage from the bearing assy. If the leakage appears to

be significant then end frame covers as shown in a figure are to be removed and the leakage should be

cleaned.

Check the Main Terminal box and Exciter Terminal Box for dust and use blower.

Check bus bars and connections for cracks or frayed insulation, ensuring complete security, of operating

personnel.

Ensure that there are no loose nuts or bolts in the machine and securely close the inspection cover. One

should be Very careful while doing the job on the an side (coupling side)

4.2.1 PERIODIC TIGHTENING OF BOLTS

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

To be done every month for the following assemblies in addition to routine inspection check, carry out with

specified torque value. Refer maintenance data for values.

Components

Torque (kgm)

Coupling bolts to engine and fan

8-10

End frame to alternator stator frame

8-10

14- 16

Cable connections to Alternator

Main bracket fixing bolts to AVM

69-83

Air inlet covers.

2-3

Replace any cracked spring/lock washer or any damaged bolt and also check locking of the remaining bolts

in rotor if it is taken out for overhauling or for bearing change.

4.2.2 INSULATION CHECK

In every 3 months, check the insulation resistance of the rotor and stator with a 500 Volts Megger and record

the IR value. The Alternator can be safely operated with a minimum hot insulation resistance of 1 to 2 Mega

ohms. Further fall in IR calls for additional cleaning and re-painting with insulating varnish of stator and

rotor. Sometimes the accumulation of moisture in the machine leads to low Insulation Resistance, then the

machine needs prolonged drying at low temperature of 100-110 °C till the insulation improves. Specially

take care of the deposition of dirt and during the first heavy rains of the season.

WHILE CHECKING WITH 500 VOLTS MEGGER SHORTENS ALL, AC

& DC BUSBARS TO AVOID DAMAGE TO THE DIODES. REMOVE

THE SHORT AFTER MEGGER CHECK.

4.2.3 RELUBRICATION

50 grams grease (see data for grade) is to be topped up in the end frame bearing assembly only after a year of

service or 150000 Kms of run which ever comes first. . This is to be done in addition to all the above checks.

4.2.4 DIODE REPLACEMENT

In the case of damage/failure in diode, diode of same polarity shall be used for replacement. It is

recommended that the make of diode be only of Ruttonsha for product reliability. After assembly, the

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

continuity of replaced diode to be checked with multimeter. Diode to be assembled at specified torque value

. For assembly please see the sketches for the detailed assembly.

4.2.5 PERIODIC OVERHAUL

The Alternator is required to be overhauled, even if the same is working satisfactorily. The period of

overhaul can be varied between 4 to 5 years depending on the conditions of operation and maintenance.

However the first overhaul is recommended before completion of 2 years as it is the first of its type in India

and to have the feed back to the manufacturer.

The routine overhaul mainly consists of

• Dismantling & cleaning

• Inspection & reconditioning

• Replacement & reassembly.

4.3 DISMANTLING & CLEANING OF ALTERNATOR:

Before undertaking dismantling Alternator, examine its OGA & PART drawings submitted to the customer

during the approval stage and follow it in presence of experienced personnel or some one from manufacturer

side.

It is recommended that, as far as possible, reassemble after overhaul, the same components, which have been

dismantled from the machine.

For dismantling refer the figure attached and proceed as follows.

Clean the Traction Alternator externally.

After removing the alternator from the Engine, Put the slot wedges provides in the air gap of pole tips in

armature portion so that sudden load is not transmitted to the bearings.

Remove bolts of end frame while alternator is kept vertical bearing side up

Use eyebolt of M20 in the taps provided and lift it with the help of wire sling slowly. As soon as the centre is

achieved the slot wedges will fall automatically to ground. It is to be replaced while making the alternator

horizontal. Use the torque level as specified in the table of technical data.

End frame is a push fit on the frame. There are three tapped holes provided on the 725PCD. Jack with M12

bolts to remove the end frame from main stator frame.

Removing the Outer Bearing cap:

Unlock and remove the bolts for the outer bearing cap and clean with a cotton waste thoroughly.

End frame can be removed from the bearing by keeping the rotor coupling face on the stand and pulling the

end frame with the help of sling. First remove from the frame as mentioned above.

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TRACTION ALTERNATOR

Remove end covers and inserts the puller bolts of M20, tapped at both the ends in the inner bearing cap. On

the other end put the plate with a hydraulic jack to pull the distance collar, bearing, shrink ring together.

4.3.1 CLEANING

All parts of the disassembled Alternator, including bearing, bearing housing is to be thoroughly cleaned

before examination.

Cleaning should be attempted by blowing dry compressed, low-pressure air followed by wiping with clean

lintless cloth. Even a stiff Nylon brush or fibre scrapper may be used. In severe cases cloth dampened with

solvent can also be used.

CHLORINATED HYDROCARBON TYPE CLEANING SOLVENTS ARE

NOT RECOMMENDED FOR USE ON EQUIPMENT BECAUSE OF

POSSIBILITY OF INSULATION DAMAGE

CLEANING SOLVENTS MAY BE TOXIC AND/OR INFLAMMABLE.

TAKE ADEQUATE PRECAUTIONS AS SPECIFIED BY SOLVENT

MANUFACTURES.

Use following cleaners:

a) For insulation: use non-oil quick drying cleaners.

b) For end bearing fits, shafts, metal surfaces use a cleaner which will not leave an oily deposit on

the finished surface.

c) For bearings use cleaner which will not completely remove the oil film from finished surfaces.

Kerosene, petroleum spirit or petroleum solvents are satisfactory.

Cleaning with steam (alternative method).

d) Heat a washing compound in a steam tank (water and cleaning compound) until the temperature

reaches 100 °C.

e) Place the parts to be cleaned in such a position that the steam can be directed from a hose in all

directions for cleaning.

f) Allow clean parts to cool and blow compressed air for removing moisture.

g) For electrical components heat them in oven till the moisture is removed.

4.3.2 INSPECTION AND RECONDITIONING:

After the thorough cleaning of all parts, inspect and recondition as follows:

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TRACTION ALTERNATOR

4.3.2.1 STATOR

After thorough cleaning of stator examine for any loose wedge or damaged insulation or hot spots. If loose

wedge is found replace them with new ones giving proper packing beneath them.

If any damaged insulation is noticed on end winding portions, the same can be locally repaired with glass

mica tapes and glass tapes.

If a hot spot is noticed on the lead joints, remove insulation and examine the brazed joint. If in doubt re-braze

taking adequate protections for surrounding coils by packing wet asbestos putty all around and carry out

torch brazing with silphos brazing alloy strip and rod. Re-insulate after re-brazing. Check insulation

resistance with a 1000 Volts Megger. IR should be greater than 20 M Ohms. H-V test is to be performed at

1kv for one minute.

If IR is found to be less than the specified limit, when alternator was not in use for a long period of time, for

developing the IR, heat the stator in an oven operating at 100 to 110 °C for 6 hours, and check insulation

resistance and continue heating till IR is satisfactory.

4.3.2.2 ROTOR

Check the rotor for any damaged or loose coils by tapping the coils using a wooden mallet. Check rotor field

coil to coil connections for looseness by tapping.

Rotor insulation resistance to be checked with a 500 Volts Megger. If IR value is more than 20M Ohms no

repair is needed to the rotor otherwise it is to be subjected to the following varnish treatment Once again

clean the rotor and the rotor coil surface and blow over the shaft barrel.

Heat the rotor in an oven operating at 100 to 110°C for 6 hours.

Check insulation resistance and continue heating till IR is satisfactory. Rotor - 150M ohms, Exciter rotor

50M ohms.

When the rotor is above the room temperature, apply two bricks coats of solvent less resin, all over the rotor

pole coils, pole body face and connections ring.

Rotor to be cured at 160

c for 10 hours.

Once again check IR value it should be greater than 40M Ohms.

Apply anti tracking insulating varnish and then rotor is to be cured at 160

C for 6 hours

FIELD CONNECTOR REPLACEMENT:

If any field connector or stator overhang is to be replaced or repaired due to damage or failure, follow the

procedure as below:

Cut the Resi-glass binding Tape on the field connector ring at the affected pole coil and remove Resi-glass

tape to the extent required. Un braze the coil to coil connector and if the coil to coil connector is damaged,

replace it with a fresh one, while replacing ensure the connections are made according to the diagram. See

Fig. Stator connection diagram. The bare connector is to be insulated as below:

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

One layer half lapped with 0.13mm x 19mm wide kapton mica tape.

Followed by one layer half lapped 0.038mm x wide P.T.F.E tape.

Followed by one layer half lapped 0.10mm x 25mm wide Glass tape.

On the lead to lead insulation between poles use one layer of kapton mica, one layer half lap of

glass mica, one layer half lap of glass tape used above.

Double the above quantity for stator overhang and 3cms on either side of damaged area.

The Resi-glass taping requires curing at 135 °C for 6 to 8 hours and the entire connector ring portion is to be

resin treated as mentioned in` rotor reconditioning. During this process remove the diode heat sink as it is not

designed for such a high temperature.

RECONDITIONING OF ROTOR FIELD COIL

REPLACEMENT:

If a particular rotor coil is to be dismounted, adopt the following procedure:

a) Mounting of field coil on rotor.

1.0 Place rotor vertically (Bearing end up)

2.0 Open coil to diode wheel connections.

3.0 Unlock and open mounting bolts.

4.0 Remove the coil support by hammering the wedge.

5.0 Isolate the faulty coil leads by removing the insulation and de brazing the joints.

6.0 Remove the tack weld of the mounting bolts.

7.0 Hold pole and coil assembly with a Nylon sling and open pole bolts. Torque required will be

around 80 kg-m.

8.0 As pole is directly wound on pole the whole new assembly. Pole is to be replaced in case of

faulty pole. Pole is subjected to VPI after forming and consolidation with epoxy resin.

9.0 Check the IR value of the coil it should be more than 150 mega ohms.

MOUNTING OF FIELD COIL

Clean pole body and paint with anti-tracking insulating varnish.

Hold pole assembly vertically up and bring near to shaft barrel. Assemble with pole bolts. Conduct HV test

on changed coil at 1.0kV for one minute and then tighten pole bolts with specified torque and tack weld to

lock it.

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TRACTION ALTERNATOR

TORQUE IT WITH 80 KG-M

BOLTS M24, CLASS 12.9

LENGTH 140 mm

DO NOT INTER CHANGE ROTOR STRIPS PLACED BELOW THE

EACH POLE WITH ONE ANOTHER. AS THIS GOVERNS THE ROTOR

DIA VARIATION.

After the field coils are installed, the coils connections are to be completed and the rotor needs to be resin

treated in line with the instruction under reconditioning.

Dynamically balance rotor, after the final assembly of diode wheel components. Balance weight can be

added on support plate and on coupling face where provision is specially made for this. Balancing should be

done at 1100 rpm within 5 GMS of residual unbalance.

4.3.2.3 BEARING COMPONENTS

Examine outer bearing cap, shrink ring, bearing cap for any dents, score marks. If they are of minor nature

attend with a oil stone and rinse. If the damage is considerable same are to be replaced with new

components.

Examine the followings:

1. Flaking or cracks in the ball path. If found, reject the Bearing.

2. Heavy electrical pitting. If found, reject the bearing.

3. Raised craters around the edges. Stone off (do not file).

4. Mottled distributed pattern of dirt denting. Scrap the Bearing.

5. Evidence of rubbing or turning on the shaft. Look for loose Spacers or interference of the

housing parts. If rubbing is Heavy or if there is wear on the shaft, reject the bearing.

Examine the outer race as follows:

Slide the outer ring by hand and if the ball drags, scrap the bearing.

Scrap the bearing if any of the following conditions are discovered on any of the bearing parts.

Severe scoring caused by inadequate lubrication.

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

Corrosive pitting caused by moisture or electrolytic action.

3. Break or crack (possibly caused by striking the shafts with a hammer during removal).

4.4 REASSEMBLY OF TRACTION ALTERNATOR

1. Fit the distance collar onto the shaft, if removed, ensuring that it is solidly up to the shaft abutment

face.

2. Fit the bearing by heating it to 100 to 110 °C and shrinking onto the shaft (if already removed),

when cold. Tap the race to ensure that it is solidly up to shaft abutment face. Put identification marks

on both the distance collar and shrink ring.

Rest of the procedure to be followed in reverse as described in clause no

9.1, and of course any other best practices can also be adopted depending

on the requirements.

STANDARD REFERENCE CONDITIONS

TEMPERATURE

These alternators are designed for an ambient temperature of 55°C. For marine and other applications where

the ambient temperature is greater than 55 °C, the alternators must be derated to ensure that the actual

temperature does not exceed the specified maximum, Outputs are normally quoted at 55 ° C. These outputs

must be multiplied by the following factors for higher ambient temperatures.

TEMPERATURE

MULTIPLIER

(°C)

0.95

ALTITUDE

Above 1000m the effectiveness of the air is reduced sufficiently to make derating necessary. For altitudes

above 1000m outputs must be multiplied by the following factors.

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TRACTION ALTERNATOR

ALTITUDES

MULTIPLIER

1,500

0.97

2,000

0.94

2,500

0.91

3,000

0.88

3,500

0.85

4,000

0.82

HUMIDITY

Machines are tropicalised and can successfully operate in high humidity levels. Correct choice of the

insulating materials and careful assessment of the impregnation varnish system and methods achieve this.

5. ALIGN MENT PROCEDURE OF ALTERNATOR WITH DIESEL ENGINE

1. Rotate the engine freely one or more round complete before alignment.

2. Check the engine crankshaft endplay and note down the end play (x). This should be measured with help

of dial bore gauge. Once the measurement is done keep the crankshaft towards vibration damper end.

3. Check the TIR(Total Indicative Reading) of flywheel housing. The check is mandatory if the engine was

taken for rebuild and housing was removed.

4. Record dimension “a” by using vernier calliper.

5. Apply little grease on flywheel pilot bore, as the rotor slides in the pilot bore during assembly as a guide.

Preparing the alternator for alignment: -

1. This alternator being a single bearing alternator Never ever attempt to rotate the alternator rotor when it is

in uncoupled condition as this may damage the windings of rotor/ stator. Alternator is shipped with rotor

locked by shipping bracket.

2. Remove the shipping bracket and mount the flex plates comprising of 8 nos.(1.2 thk) on the rotor by 8 nos

hex head bolts M20X55 long and torque them to 100 lb-ft torque. Engage alternator fan with outer diameter

of coupling.

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

3. Place the hand-operated jack properly to lift up the rotor and measure the distance between the rotor and

stator frame. This should be considered to be accurate when measurement in all the directions is equal. This

exercise should be made with a view to make the rotor shaft horizontal to axis of the alternator/rear bearing.

4. Now measure the endplay of rotor by playing the rotor shaft

from rear end, note this play as “y” and

finally keep the rotor pushed to the rear end.

5. Measure the dimension “b” with the vernier calliper and note.

Dim “a” stand for distance between alternator stator spigot face &

flex plate face, which is fixed on rotor shaft.

Dim “b” stands for distance between engine adopter spigot face &

flywheel face.

Shim selection:

1. if a> b then add up the shims between flex plate & Rotor shaft. These shims must have

thickness as, 0.1 mm, 0.25 mm, 0.5mm, 1.0mm, and 1.6mm.

2. Thickness of shims to be added :- (a-b) + (x+y)/2

3. Choose the thickness of shims nearest in multiples of 0.1mm so that both rotor and crankshaft

are at the centre of the travel in their bearing.

4. Two studs 5/8” unc x 100 mm long are to be fixed diagonally opposite in flex plate mounting

hole of engine flywheel.

5. Move/Tilt the alternator to locate studs that are fixed in flywheel, visibly with the holes in flex

plate.

16 nos socket head cap screws M16X70mm to be used for holding stator frame of alternator

with adopter plate of engine with standard bolt tightening practice (diagonally opposite bolts).

7. Cummins supplied 2 nos out of 8no’s hex head bolt 1/2” unc x 3.5 inch to be inserted through

alternator fan, flex plate to flywheel. These bolts are to be partly tightened.

8. Both the studs are taken out safely through alternator fan.

9. Remaining all the 10 bolts are to be placed at vacated fixing locations. All the 12 bolts are to

be tightened at specified torque value followed by the standard tightening practice.

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TRACTION ALTERNATOR

After assembly of alternator match the load characteristics.

If there is an abnormal change in the characteristics, then

attention is to be paid on the root cause.

6. PROTECTION OF BALL ROLLER BEARINGS

6.1 GENERAL

The ball bearing incorporated into CG Traction machines is of high quality and adequate capacity as

supplied by the leading bearing manufacturers. Every care is taken during assembly to ensure that

the correct fitting-tools are employed, and strict cleanliness observed, to achieve long and trouble-

free operation of bearings in service.

It is essential that equal care is taken of bearings, which may be subject to removal and replacement

during normal overhaul procedures, and of new bearings to be fitted when renewal is necessary.

Bearings seldom break down as a result of normal usage; the most common causes of bearing failure

can be traced to mishandling, damage or stress set up during fitting or removal, dirt, corrosion, and

over or under lubrication.

ALWAYS CLEAN BEARING COVERS, CAPS AND HOUSINGS BEFORE

REMOVING BEARINGS, AND USE CORRECT WITHDRAWAL AND

REFITTING TOOLS.

The following information is a general guide to the care and use of roller bearings. More detailed

literature is obtainable from the appropriate bearing manufacturers.

6.2 FITTING AND REMOVING BEARINGS

1) The use of a press or extractor is preferable than to a hammer and drift whenever possible. It is

also preferable to immerse bearing in oil at a temperature of 100 °C for 25-30 minutes, or place in an

oven under the same conditions.

2) If it is necessary to hammer the tool when removing a shaft nut or bearing retaining nut, always

firmly support the shaft, to avoid shock-loading the rolling elements or races.

3) Never strike a bearing directly with a hammer; a mild steel or brass drift or tube should be

interposed between hammer and bearing. The end of the drift or tube in contact with the bearing

should be squared off and free from burrs.

4) Check bearing housings for signs of race creepage.

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

5) When using presses, extractors or drifts for the fitting/removal of bearings it is essential that no

load be transmitted through the rolling elements of the bearing.

6.3 INTERCHANGEABILITY OF BEARING COMPONENTS

Roller bearing components must not be inter changed.

NOTE: Bearing failure can occur as a result of accidental or indiscriminate interchanging of bearing

components. The component parts of individual bearings must be kept together at all times and not

mixed with other, similar, bearings and bearing components.

6.4 CLEANING AND ANTI-CORROSION TREATMENT

A. General Treatment

Avoid the temptation to spin a bearing after it has been removed from an assembly, and before

cleaning; this is to avoid compressing hard particles, which may be present in the lubricant, thereby

initiating track defects.

B. Bearings which should not be cleaned

Do not clean bearings, which are to be returned to the manufacturer for defect examination; such

bearings should immediately be wrapped in grease-resisting paper and boxed.

C. Cleaning the bearings

The importance of cleanliness when dealing with bearings cannot be too highly emphasised. The

parts must be scrupulously clean to enable accurate assessment of serviceability to be made and, if

found to be serviceable, it is of equal importance that they be maintained in a clean condition for

subsequent build into the assembly.

To minimise the risk or corrosion by handling, it is recommended that, so far as is possible,

operators should wear protective gloves during and after the cleaning process.

Bearings or components incorporating bearing surfaces, must in no circumstances be left in a dry

condition, or unprotected against corrosion.

Tri-chloro-ethylene, carbon tetrachloride, or paraffin should not to be

used for cleaning bearings, as any of these agents can promote corrosion.

D. Cleaning Equipment

Where large numbers of bearings are to be processed it may be advisable to provide separate

cleaning, rinsing and inhibiting tanks of a size appropriate to the volume of work. Each tank may be

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

constructed of mild steel and should be equipped with a drain plug. Wire mesh baskets or platforms

should be provided to hold the bearings clear of sediment in the bottom of the tank. The inhibiting

oil tank should be heated to 90 ° to 100 °C (194 ° to 212 ° F).

1) Initial cleaning tank

The tank should contain an adequate quantity of white spirit / gasoline and should be drained,

cleaned out, and refilled with fresh liquid whenever approximately 100 bearings per gallon of liquid

have been processed, or when excessive contamination is suspected.

2) Second-wash tank

Also to contain white spirit / gasoline and to be topped up with fresh, clean liquid to replace drag-out

losses.

3) Inhibiting oil tank

The tank to contain inhibiting oil such as shell Ensis 100.

4) Mineral jelly tank

The mineral jelly must be maintained at 80 ° to 90 °C

(176 ° to 194°F) and be periodically topped

up to replace drag-out losses.

The tank should be cleaned out and refilled with fresh mineral jelly whenever contamination is

suspected.

E. Cleaning and temporary inhibiting

To minimise the possibilities of corrosion on the bearing surfaces during cleaning and subsequent

inspection, it is recommended that bearings should not remain unwrapped for more than 4 to 5 hours

while temporarily inhibited. Bearings should always be immersed in a horizontal position in the

cleaning and inhibiting fluids to avoid the retention of air pockets. Rotate the bearings during the

cleaning operation.

The following sequence of operations is recommended and should be carried through with the least

possible delay between each

operation.

1) Wash the bearings in the initial wash tank using a bristle brush to remove all dirt or old lubricant.

2) Remove the bearings from the wash tank and allow draining for 5 minutes.

After the initial wash, carbonised bearings may be soaked in hot mineral

oil (90 ° to 100 °C, 194 ° to 212 °F); agitating the bearings slowly, from

time to time. Badly carbonised bearings may be cleaned in a strong

alkaline solution; see the appropriate manufacturer's instructions.

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

3) Completely immerse and wash the bearings in the second wash tank.

4) Remove the bearings from the tank and allow draining for 5 minutes.

5) Immerse the bearings in the inhibiting oil tank for temporary protection against corrosion.

6) Remove the bearings from the oil and allow thoroughly draining and cooling in still, dry, dust free

air.

At this stage, the bearings should be examined for Defects; however, if

some delay between cleaning and examination is unavoidable, the

components should be wrapped in grease resisting paper.

F. Treatment of new bearings

New bearings should not be removed from the package until immediately before fitting. It is

preferable to remove the preservative from the rolling members and race surfaces by immersion in

the inhibiting oil tank as in E5 and 6.

G. Treatment after inspection

After inspection, again wash and inhibit the bearings as described.

If the bearings are not immediately required for fitting they must be wrapped in grease-resisting

paper or unsealed polythene envelopes. Bearing may be stored in this condition for up to 14 days.

Bearings to be stored for longer periods should be treated as follows: -

1) Totally immerse the bearings in the mineral jelly tank for approximately 10 minutes.

2) After cooling, dip the bearing a second time into the mineral jelly, remove immediately and wrap

the bearing In grease-resisting paper. Store in a dust tight box.

6.5 INSPECTION

After cleaning, bearings should be thoroughly inspected together with associated components, such

as seals. The housings and shafts from which the bearings have been removed should also be

examined. Thoroughly examine each bearing for visual defects such as rust and discoloration,

cracks, wear, indentations and bruising, and track defects. Bearings associated with electrical

machines may sometimes be found to contain craters or pits caused by electrical arcing. The craters

will

have a centre of black, fused, metal. Unless the damage to the rolling element or track is

slight, bearings should be rejected.

Rust and corrosion

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

Rust on the rolling elements is not acceptable and the bearing should be rejected. Very light

corrosion pitting on the races may be accepted, depending upon the speed and loading of bearings.

B. Discoloration

Slight discoloration of the rolling elements or tracks is acceptable, but if the components turn blue or

brown, indicating excessive heat, the bearing must be rejected.

C. Cracks and fractures

In all cases, the bearing must be rejected

D. Flaking

Flaking appears when fragments of material have broken away from the bearing track. Subsequent

wear in the bearing due to increasing stresses is accelerated. Then bearing must be rejected.

E. Smearing

Smearing is the result of the balls or rollers sliding rather than rolling in relation to the tracks ocage,

causing incipient seizure. The bearing should be rejected.

F. Wear

Excessive wear does not occur during normal operation of the bearing. It is generally the result of

misuse in fitting, external vibration when the machine is stationary - causing local shock-loading via

the rolling elements of the bearing, or the ingress of dirt, inadequate or incorrect lubrication is also a

contributory factor.

Non-operating surfaces

(a) Light rust may be removed with fine abrasive cloth, and the bearing thoroughly re-washed as

described Shafts and housings The shafts and housing associated with bearings undergoing

inspection should be examined for defects. Pick-up or scoring on surfaces, which make contact to the

bearing must be rectified by stoning or dressing.

Surfaces, which are worn below the drawing limits, should be built up if possible or the shaft or

housing renewed.

MAINTENANCE MANUAL FOR DETC-US

TRACTION ALTERNATOR

NOTES

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MAINTENANCE MANUAL FOR DETC-US

POWER RECTIFIER

CHAPTER VI

POWER RECTIFIER

1. BRIEF SPECIFICATIONS

The Rectifier Unit Conforms to Crompton Greaves Specification No. TE 10002 R0 27.05.2016 and ICF

specification ICF/MD/SPEC - 300 R0 DATED 16-04-2016 as per following brief specifications.

1. Rectifier Type

3 Phase Bridge type

2. No. of Bridge in Parallel

Three Nos.

3. Max. continuous current

750 Amps. D.C.

4. Max. one hour rating

1000 Amps. DC

5. Starting Max. current for 5 Min

1200 Amps. D.C.

6. Max. output voltage

900 V.D.C.

7. Max. Ambient Temp.

47°C

8. Cooling

Forced Air

9. Cooling Blower Supply

110 Volts D.C.

10. Mounting of Rectifier

On Board

11. Dimensions mm. (H x L x W)

1695 x 800 x 450 without side panels

12 Weight

330 Kgs. Approx

The On-Board mounted Rectifier Unit has been designed to feed the Traction Motor load of the 700 HP DETC.

It has been designed to work on 660 Volts max, 3 Phase, 3 Wires AC Input supply derived from underslung

alternator. The Rectifier Unit has been designed to withstand shocks and vibrations encountered in service of a

rolling stock. It rectifies the three-phase AC voltage into a DC voltage. The equipment meets the requirement of

IS: 7788.

2. FUNCTION OF THE RECTIFIER UNIT

The function of the Rectifier is to convert a three-phase supply into DC Voltage, for driving Traction Motors

connected in parallel across the Rectifier. Each of the three bridges are protected by Semiconductor grade Fuses

at the input. In case of a diode failure, the particular bridge is isolated by its fuses. The other two bridges

continue to supply the full load current to the Traction Motors. Hence, n-1 redundancy is built-in. Each of the

Main fuses have a smaller fuse called trip-fuse connected across it. When the Main fuse blows the fault current

is diverted to these trip fuses. These in turn clear the fault current and in the process operate a plunger, which

hits a Micro-switch. This condition stays latched and can be reset only by replacing the Main Fuse and the Trip

Fuse. The potential free N/O & N/C contacts of the Micro switches in turn operate a Contactor to give an

indication in driver’s cabin that a Fuse has blown. In a similar manner failure of a second bridge is indicated by

the operation of a second Contactor. In this condition the Control Circuit of the DETC must reduce the

maximum load current. A single bridge will no longer be able to carry the full load current of the Traction

Motors. Suitable corrective action must be taken. The Rectifier is protected at the input and the output by

suitable Damping Circuits.

The Rectifier is cooled by forcing air through the fins of the Heat Sink. Force cooling is achieved with the help

of a Axial fan arrangement. The Axial Fan operates from 110 VDC Auxiliary Power Supply. The fan, while

working, generates a positive pressure inside its casing. This pressure is sensed by a Pressure Switch. In case of

MAINTENANCE MANUAL FOR DETC-US

POWER RECTIFIER

failure of the Axial fan this pressure will drop and is sensed by the Pressure Switch and the information is

transmitted to the Control Circuit through its NO & NC potential free contacts.

3. DESCRIPTION OF THE RECTIFIER UNIT

The Rectifier has an AC Input and the DC Output terminals are on front bottom side. The Fan draws air from

the engine compartment from top and pushes down through the fins of the Heat Sink and is discharged to the

atmosphere through bottom floor.

The side panels of the rectifier unit are made of MS with backup of FRP sheet on inner side for creating higher

creepage path with live terminals of the unit. These are bolted to main frame.

AC & DC Power Terminals (busbars) are accessible by opening front lower panel and Auxiliary Terminal

Board and CT & PT Terminals are accessible by opening rear lower panel.

The Diodes and Fuses are accessible by removing front upper panel. The arrangement is as shown below.

D10

D11

D12

FR1

FY1

FB1

BRIDGE - 1

FR2

FY2

FB2

BRIDGE - 2

D13

D14

D15

D16

D17

D18

FR3

FY3

FB4

BRIDGE - 3

Diodes D1 to D9

- Type OSD 595 N36SQ (With Red cover sleeve)

Diode D10 to D18

- Type OSD 595 P36SQ (With Blue cover sleeve)

FR - Fuses 725 A, 1000 V

MAINTENANCE MANUAL FOR DETC-US

POWER RECTIFIER

4. PRE INSTALLTION CHECKS AND COMMISSIONING

4.1 RECEIPT INSPECTION

To facilitate transportation, the rectifier unit should be packed thoroughly in wooden crate. On receipt the crate

shall be checked for any damage. Any visible sign of damage should be reported to us. After unpacking check

the unit internally & externally for any visual damage. Any damage if found, should be reported to us.

During the period of unpacking and inspection it must be seen that the unit is not damaged. After unpacking

Insulation Resistance and HV Breakdown tests may be performed if necessary.

4.2 INSTALLATION

The Rectifier Unit should be lifted and placed in position using the 4 lifting eyebolts that fitted on top side of the

unit. Rectifier Unit should be fixed by the 4 mounting bolts and nuts.

Then connect

a. Input and output cables to the respective terminals

b. 110 VDC supply and Control cables to the control terminal board

4.3 COMMISSIONING

The unit must be subjected to routine checkup including checking of the relevant connections. One has to go

through the technical particulars and general feature sections. After checking all the details the Rectifier Unit is

ready for use.

Before applying Main AC Power to rectifier, following procedure to be followed.

Axial Fan: The fan speed has been set to give required air flow through rectifier heatsink duct. However it

should be checked for air flow from 90 VDC to 125 VDC supply. A potentiometer control has been provided to

set fan speed. It can be accessed by opened by removing left side panel.

The fan speed should be set such that at 90 VDC supply it gives minimum 5 mts./sec air velocity through

rectifier heatsink duct and should not trip at 125 VDC because of its internal O/L trip mechanism.

Now unit can be energized with 3 Phase AC Supply.

Initially the load may be at half the value for few hours. Check all the components and joints for any abnormal

heating or temperature rise or failure. The Load may be gradually increased, in steps till full load is reached. It

is suggested to report any abnormal behavior to the manufacturer.

MAINTENANCE MANUAL FOR DETC-US

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