FIELD OF INVENTION
The invention relates to a dual-mode operable rectifier-mounted brushless
synchronous alternator for ballast cleaning machine application including traction
application.
BACKGROUND OF INVENTION
Ballast Cleaning Machine is a two-unit railroad machine used for the cleaning of
the ballast (gravel stones) in the whole profile of the rail bed.
Heavier rails and Pre-stressed Concrete (PSC) sleepers are presently used on
railway tracks in many countries of the world. The heavier track structure thus
adopted is not susceptible to manual maintenance and requires maintenance
through track machines. In such track machines, the brushless alternator
warrants a configuration such that it can simultaneously work in dual mode i.e.
in travel mode (traction application) as well as in working mode (Ballast
cleaning). In the Travel Mode, the alternator supplies DC power to the traction
motors in cooperation with the uncontrolled power output of the rectifier and the
speed governor. The travel speed control is exercised through a stepwise speed
variation of the Diesel engine. The speed range of the alternator is between 700-
1800 RPM. In the Working mode, the alternator runs at a constant speed of 1500
RPM. In the Railways such a cleaning operation is mandatory once in at least 10
years for broad gauge tracks. Hence this is an important maintenance activity to
improve drainage and resilience of the track.

OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a dual-mode operable
rectifier-mounted brushless synchronous alternator, which eliminates the
disadvantages of the prior art.
Another object of the invention is to propose a dual-mode operable rectifier-
mounted brushless synchronous alternator, which is capable to simultaneously
working in travel-mode and in working mode.
A still another object of the invention is to propose a dual-mode operable
rectifier-mounted brushless synchronous alternator, which is enabled to operate
at a varying speed during the travel-mode but at a constant speed in the working
mode.
Yet another object of the invention is to propose a dual-mode operable rectifier-
mounted brushless synchronous alternator, which is configured as a compact,
and light -weighted by providing an improved frame structure and a modified
rectifier assembly mounted on a location hitherto unutilized.
A further object of the invention is to propose a dual-mode operable rectifier-
mounted brushless synchronous alternator, which is capable to realize a split -
winding feature.
A still further object of the invention is to propose a dual-mode operable rectifier-
mounted brushless synchronous alternator, which is reliable and safe.

SUMMARY OF THE INVENTION
Accordingly, the invention proposes a dual-mode operable rectifier - mounted
brushless alternator, in particular for ballast cleaning machine application, which
is further applicable under load conditions on traveling mode. In the Travel
Mode, the alternator supplies the DC power to the traction motors of the
locomotive in cooperation with an uncontrolled power output of the rectifier and
the speed governor. The travel speed control is being exercised through a
stepwise speed variation of the DIESEL engine of the locomotive. The speed
range of the alternator is between 700 -1800 RPM. In the Working mode the
alternator runs at a constant speed of 1500 RPM.
Accordingly, there is provided a dual-mode operable rectifier - mounted
brushless synchronous alternator, the alternator being enabled to operate a
ballast cleaning machine in a working - mode including in a travel-mode, for
maintenance of the railway track, the alternator supplying a D.C. power in
cooperation with an uncontrolled power output of the rectifier including the
speed governor in a travel mode to the locomotive, the travel speed control
being exercised through a step-wise variation of the diesel engine of the
locomotive, wherein a constant running speed of the alternator is maintained in
the working-mode, the alternator comprising; a stator in a capsule shape having
a stator core formed of one-piece low-loss steel lamination stacked together,
copper performer with class-H insulation adapted as stator coils and inserted into
the stator slots in the core and joined together forming a 3-phase winding which

are brought - out for supply through a plurality of connection rings; a light -
weight magnetic frame of tubular construction allows an easy assembly and
dismantling of the alternator; a high power exciter having an armature core and
a stator core each made of sheet steel lamination, and a diode wheel assembly
both together being covered by an end cover in two halves; a modified and
compact rectifier with mounting disposed on an hitherto unutilized space above
the exciter assembly for DC-supply to the traction motor; a rotating rectifier
bridge assembly mounted on a rotor shaft; the rectifier mounting comprising a
dual supply power pack for simultaneous operation in dual modes in a dual-
supply power pack which is catered for by the combination of the high power
exciter and the diode wheel, in that the alternator is provided with a dual
connection characteristics for operating in dual mode including coupling and
aligning with the diesel engine, and in that a split - winding feature is realized by
the high power exciter to cater magnetic field requirement of the alternator
through pre-assessment of the open circuit characteristic and short circuit
characteristic.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig. 1 illustrates a sectional diagram of the dual-mode operable brushless
synchronous alternator of the invention displaying the constitutes components.
Fig. 2 illustrates a long section of the dual-mode operable brushless synchronous
alternator of the invention displaying the constituent components.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
The dual-mode operable rectifier - mounted brushless synchronous alternator
provides a compact arrangement of rectifier mounting. As shown in fig - 1, the
alternator has a dual connection characteristic for operating in traveling as well
as in working mode. The alternator is enabled for coupling and aligning with the
diesel engine. A capsule type design of wound stator, provisions for self start and
many more features are provided in the alternator. A split winding feature has
been achieved as shown through an example by designing and reviewing the
electrical parameters and the new designed exciter (20) introduced to cater pre-
assessment of the open circuit and short circuit characteristics.
As illustrated in Fig. 1, the stator core (3), made of one- piece low loss steel
laminations (2), are stacked together to form a complete stator construction. The
stator coils (1) are class 'H' insulated, using a qualitative insulating material and
inserted in stator slots.
The stator coils (1) is insulated copper which are placed inside the slots in the
core (3) and joined together in the form of a 3-phase winding. The stator coils
(1) which have multiple number of turns, are consolidated together before
insertion in to the slots.

The 3-phase electrical connection of the stator winding are brought out for
supply by a plurality of connection rings (9) as a shown in Fig. 2.
As shown in fig. -2 a frame (4) of the alternator is of tubular construction, sturdy
and light in weight. The newly configured frame (4), an end shield (6, 7) a diode
wheel (19) exciter assembly (12 & 18) and a rotor assembly (14) allow an easy
assembly and dismantling of the alternator. Lifting lugs (8) are installed on the
frame (4) for lifting the alternator with a conventional overhead hoist. In order to
make the machine compact, the rectifier (20) is mounted on the top of the
exciter (12,18) utilizing the space available over the exciter (12,18) for DC supply
to the traction motors. A removable drip-proof, louvered cover (24) in two halves
encloses the exciter assembly (12 & 18) and the diode wheel (19).
The rectifier-mounted brushless alternator with a compact arrangement (22) for
rectifier mounting is having a dual supply power pack in a single machine for two
simultaneous operations at a time. The high power exciter (12,18) and the diode
wheel (19) in combination caters for the requirement of the dual power supply.
The stator (1, 2, 3) is a capsule type of design. All the electrical performance /
parameters have been achieved by designing and reviewing the required / test
parameters.
A plurality of mid tapping (21) of all three phases are taken out and sent to the
3-phase rectifier (20) to rectify the AC supply into DC supply for DC traction
motors in traveling mode application. The output of the traction alternator is fed
to the Ballast cleaning machine in working mode.

Exciter armature core (18) is made of sheet steel lamination (2) stacked together
and armature coils of enameled copper are placed inside the slots in the core
(18) and joined together in the form of 3-phase winding.
Exciter stator core (12) made of sheet lamination (2), with pole type
configuration (17), are stacked together and filed coils (1) are placed on the
poles. The field coils (1) are joined together in series by brazing the leads.
Rotating rectifier bridge assembly is mounted on the rotor shaft (14) and the
rotating rectifier assembly (20) consists of a full wave rectifier bridge made of six
semi-conductor devices mounted on aluminum heat sinks and are retained in the
heat-sink assemblies with retaining nuts and washers.
This invention constitutes synchronizing of these parameters which have been
developed to achieve the desired power required in traveling as well as in
working mode of service for use on Ballast cleaning application.

WE CLAIM
1. A dual-mode operable rectifier - mounted brushless synchronous
alternator, the alternator being enabled to operate a ballast cleaning
machine in a working - mode including in a travel-mode, for maintenance
of the railway track, the alternator supplying a D.C. power in cooperation
with an uncontrolled power output of the rectifier including the speed
governor in a travel mode to the locomotive, the travel speed control
being exercised through a step-wise variation of the diesel engine of the
locomotive, wherein a constant running speed of the alternator is
maintained in the working-mode, the alternator comprising :
- a stator in a capsule shape having a stator core (3) formed of one-
piece low-loss steel lamination (2) stacked together, copper
performer with class-H insulation adapted as stator coils (1) and
inserted into the stator slots in the core (3) and joined together
forming a 3-phase winding which are brought - out for supply
through a plurality of connection rings (9);
- a light - weight magnetic frame (4) of tubular construction allows
an easy assembly and dismantling of the alternator;
- a high power exciter (12,18) having an armature core (18) and a
stator core (12) each made of sheet steel lamination, and a diode
wheel assembly (19) both together being covered by an end cover
(24) in two halves;

- a modified and compact rectifier with mounting (20,22) disposed
on an hitherto unutilized space above the exciter assembly (12,18)
for DC-supply to the traction motor;
- a rotating rectifier bridge assembly (19) mounted on a rotor shaft
(14);
characterized in that the rectifier mounting comprising a dual supply
power pack for simultaneous operation in dual modes in a dual-supply
power pack which is catered for by the combination of the high power
exciter and the diode wheel, in that the alternator is provided with a
dual connection characteristics for operating in dual mode including
coupling and aligning with the diesel engine, and in that a split -
winding feature is realized by the high power exciter to cater magnetic
field requirement of the alternator through pre-assessment of the open
circuit characteristic and short circuit characteristic.
2. The alternator as claimed in claim 1, comprising a plurality of mid-tapping
(21) of all the three phases which are tapped and sent to the 3-phase
rectifier (20) for converting the A.C. supply into D.C. supply for the DC
traction motors.
3. The alternator as claimed in claim 1, wherein the exciter stator core (12)
is made of sheet steel lamination with a pole type configuration.

4. The alternator as claimed in claim 1, wherein the rotating rectifier bridge
assembly (19) comprises a full wave rectifier bridge made of six semi
conductor devices mounted on aluminium heat sinks.
5. The alternator as claimed in claim 1, comprising a plurality of lifting lugs
(8) installed on the frame (4).
6. The alternator as claimed in claim of the preceding claims, wherein the
speed of the alternator in travel mode ranges between 700-1800 rpm.
7. The alternator as claimed in claim of the preceding claims, wherein the
constant speed maintained for the alternator in working mode is about
1500 rpm.
8. A dual-mode operable rectified - mounted brushless synchronous
alternator, as herein described and illustrated with reference to the
accompanying drawings.

This invention relates to a dual-mode operable rectifier - mounted brushless alternator, in particular for ballast cleaning machine application, which is further applicable under load conditions on traveling mode. In the Travel Mode, the alternator supplies the DC power to the traction motors of the locomotive in
cooperation with an uncontrolled power output of the rectifier and the speed governor. The travel speed control is being exercised through a stepwise speed variation of the DIESEL engine of the locomotive. The speed range of the
alternator is between 700 -1800 RPM. In the Working mode the alternator runs at a constant speed of 1500 RPM.