FIELD OF THE INVENTION:
The present invention relates to the field of standard and broad gauge EMU/
metro application in general and to three phase AC traction motors in particular.
More particularly, the invention relates to a frameless, fully suspended, 230 kW
AC traction motor for standard and broad gauge EMU/ metro application.
BACKGROUND OF THE INVENTION:
At present, most of the trains operating in India for various applications e.g.
Main Line passenger & goods, Electrical Multiple Unit (EMU), Underground Metro
etc run on Broad Gauge track which has a distance of 1676 mm between the
rails. Outer dimensions of prior art traction motors employed in broad gauge
application are as per said boundary limits of broad gauge track.
Standard gauge having a reduced distance of 1435 mm between the rails has
been now introduced by the railways for metro and EMU applications. Moreover,
loading level of the trains and speed requirement has also been increased. As the
prior art traction motors of broad gauge application can not be accommodated in
bogie of standard gauge due to space limitation, hence there is a need for a
suitable three phase traction motor with high reliability which has external
dimensions to suit the boundary limits of standard gauge track.

CONSTRUCTIONAL FEATURES OF PRIOR ART TRACTION MOTOR:
1. FRAME AND STATOR CORE:
The exterior of the earlier traction motor is provided with cast steel outer frame
(item1). Inner diameter of stator frame (item1) is accurately machined to ensure
fitting of stator main and end laminations (item 2 & 3). The Stator core is made
from low loss electrical grade sheet steel laminations (item 2) insulated from
each other, stator end laminations (item 3) which are also made from low loss
electrical grade sheet steel laminations provided at both the ends. Stator main
and end laminations (item 2 & 3) are stacked under pressure and shrink fitted in
stator frame (iteml) between stator clamping ring at DE (item 4) and at NDE
(item 5) side. The stator frame (iteml) is provided with nose which is supported
on the bogie. The motor is suspended on the wheel axle with axle suspension
roller bearings at DE side (item 6) and at NDE side (item 7), hence motor is
termed as axle suspended motor. A separate suspension tube (item 8) covering
the axle and bolted with frame (item 1) is provided for housing arrangement of
axle suspension bearings (item 6 & 7).
2. STATOR WINDING:
The stator coils (item 9) are made from polyimide covered copper conductors
and are housed in stator slots using polyimide slot liners. The stator is LAP
wound having single parallel path. The coils are insulated with class 200
insulating materials and are held down in slots with epoxy glass slot wedges
(item 10). The wound assembly of stator is vacuum pressure impregnated with
solventless silicone resin.

3. ROTOR CORE :
The rotor core is also built from low loss electrical grade sheet steel laminations
(item 11) insulated from each other and are directly stacked on shaft (item 12)
under pressure with rotor clamping rings at DE side (item 13) and at NDE side
(item 14).
4. ROTOR WINDING :
Straight copper bars (item 15) having rectangular cross section are inserted in
semi closed radial slots around periphery of rotor core. These rotor bars are
short circuited together at both the ends by Short circuiting rings (item 16) by
silver alloy induction brazing.
5. VENTILATION ARRANGEMENT:
The traction motor is self-ventilated. A separate air inlet chamber (item 17) is
provided at non driving end of motor. A bellow (item 18) is mounted on air inlet
chamber (item 17) and an aluminium fan (item 19) is also mounted on shaft
(item 12) by bolting arrangement inside the air inlet chamber (item 17). At
driving end of motor, one another aluminium fan (item 20) is provided. Axial
ventilation holes are provided in stator and rotor core. Both the fans (item 19 &
20) draw air inside the motor for cooling of stator and rotor. Air enters into
motor through bellow (item 18), air inlet chamber (item 17) due to sucking
action of fans (item 19 & 20), passes through ventilation holes and air gap
between stator and rotor and finally exits from air outlet chamber (item 21)
provided at top of driving end side.

6. TERMINAL BOX:
Stator winding is comprising of three phases R,Y & B. Outer terminals of phases
are terminated at terminal box (item 22) welded at top of stator core at NDE
side.
7. SPEED SENSOR AND TEMPERATURE SENSOR:
Speed sensor arrangement (item 23) is provided at NDE side of motor for
monitoring the speed of motor. For monitoring the temperature rise of machine
in service a temperature sensor (item 24) is also provided.
8. END SHIELDS AND MOTOR BEARINGS:
Stator frame (item 1) is machined to ensure alignment of the end shields. End
shield DE (item 25) and End shield NDE (item 26) are spigoted into the frame
with slight interference fit and held in position by means of bolts. Grease
lubricated Roller bearings are provided at driving end (item 27) & non-driving
end (item 28) side of motor. The bearing assemblies are of sealed type provided
with labyrinths to avoid contamination of grease with dirt, moisture etc.
9. ARRANGEMENT OF POWER TRANSMISSION:
The power transmission to the bogie axle consists of a single reduction gear unit,
the pinion (item 29) of which is shrink-fit on to the motor shaft (item 12) and the
gear wheel (item 30) is mounted directly on the axle. The gear wheel is housed
in a gear case (item 31) mounted on the motor which is made in two halves
bolted together.

OBJECTS OF THE INVENTION:
It is therefore an object of the invention to propose new three phase AC traction
motor suitable for standard gauge Metro and EMU application.
Another objective of the invention is to provide a frameless machine with class-
200 insulation system resulting in higher power to weight ratio along with high
temperature rise limits during application.
A further objective of the invention is to provide a machine directly mounted on
the bogie transom which requires less maintenance compared to axle suspension
used in prior art.
SUMMARY OF THE INVENTION :
For standard gauge metro and EMU applications, 230 kW three phase AC traction
motor has been designed which can also be used for broad gauge metro and
EMU applications.
The proposed traction motor also meets increased loading and high speed
requirement in metro and EMU trains. One traction motor transmits power to one
axle of the bogie.
In view of space limitation of the application and to reduce weight of proposed
traction motor ,it is designed without outer frame having high power to weight
ratio.

To further reduce the weight of motor and to make its suspension arrangement
maintenance free, axle suspension arrangement provided in prior art has been
eliminated. The new traction motor is directly mounted on the bogie with the
help of bolts which is termed as full suspension on bogie.
For further reduction in size air inlet arrangement is provided on top of NDE side
end shield while in prior art separate air inlet chamber is provided at NDE side.
The traction motor is designed with class 200 insulation scheme having high
temperature rise limits during application resulting in higher load bearing
capacity.
BRIEF DESCRIPTION OF ACCOMPANYING DRAWINGS:
Figure 1: Shows the Long section of new Traction Motor according to the
invention.
Figure 2: Shows the Long section of prior art Traction Motor.

DETAIL DESCRIPTION OF THE INVENTION
CONSTRUCTIONAL FEATURES OF TRACTION MOTOR
1. STATOR CORE:
The exterior of the traction motor is frameless type. The Stator core is built from
high quality electrical grade sheet steel laminations (item 1) insulated from each
other, consolidated under pressure and are held together between stator end
chambers at driving end (item 2) and non- driving end (item 3). Four rectangular
steel bars (item 4) are welded at 45 ° angle with laminations (item 1) , stator
end chambers at driving end (item 2) and non-driving end (item 3). The stator
core is also welded with bogie fitting nose and fitting seat. Holes are provided in
fitting nose so as to mount the motor on bogie transom with the help of suitable
bolts. As the motor does not suspend on the wheel axle and suspended fully on
bogie hence motor is termed as fully suspended motor.
2. STATOR WINDING :
The stator coils (item 5) are made from heat sealed polyimide covered copper
conductors and are housed in stator slots using polyimide slot liners. The stator
is LAP wound having single parallel path. The coils are insulated with class 200
insulating materials and are held down in slots with epoxy glass slot wedges. The
end portions of stator coil are supported with epoxy rings (item 6) and tightened
with support clamps (item 7) which are screwed to stator end chambers at both
the sides. This supporting arrangement reduces the chances of damage to stator
coils (item 5) due to severe vibration during service. The wound assembly of
stator is vacuum pressure impregnated with high temperature class solventless
silicone resin.

3. ROTOR CORE :
The rotor core is also built from high quality electrical grade sheet steel
laminations (item 8) insulated from each other, assembled on shaft (item 9) and
are consolidated under pressure between two rotor end plates (item 10). To fix
the location of laminations (item 8) a key is used.
4. ROTOR WINDING :
Straight copper bars (item 11) having half round rectangular cross section are
inserted in semi closed radial slots around periphery of rotor core. These rotor
bars are short circuited together at both the ends by Short circuiting rings (item
12) by silver alloy induction brazing.
5. VENTILATION ARRANGEMENT:
The traction motor is self-ventilated. An aluminium fan (item 13) is provided at
driving end of motor which draws air inside the motor for cooling of stator and
rotor. Air inlet opening with mesh & top cover (item 14) is provided at top of
NDE side end shield (item 19). Axial ventilation holes are provided in stator and
rotor core. Air enters into motor through air inlet opening due to sucking action
of fan (item 13), passes through ventilation holes and air gap between stator
and rotor and finally exits from openings provided at DE side end shield (item
18).

6. TERMINAL BOX:
Stator winding is comprising of three phases R,Y & B. Outer terminals of phases
are terminated at terminal box(item 15) provided at top of stator core at NDE
side. The terminal box (item 15) facilitates further connections of outgoing
cables of motor.
7. SPEED SENSOR AND TEMPERATURE SENSOR:
For precise speed torque control of the motor an electromagnetic induction type
speed sensor (item 16) is provided at NDE side of motor.
For monitoring the temperature rise of running machine a RTD type temperature
sensor (item 17) is also provided on stator core fitted deep up to the stator tooth
level.
8. END SHIELDS AND MOTOR BEARINGS:
Stator end chambers at driving end (item 2) and non-driving end (item 3) are
machined to ensure alignment of the end shields. End shield DE (item 18) and
End shield NDE (item 19) are bolted to the respective stator end chambers. The
construction of the end shields at both the ends is such that end shields can be
removed without pulling out the inner race of the bearings from the shaft.

Grease lubricated Roller bearings (item 20) and ball bearings (item 21) are
provided at driving end & non-driving end side respectively. Adequate labyrinths
are formed in bearing cap section to prevent escape of lubricating grease or
entry of dirt and moisture. Grease nipples are provided for both the bearings for
periodical lubrication without dismantling the bearings.
9. ARRANGEMENT OF POWER TRANSMISSION:
Power is transmitted to bogie axle through a gear unit. Pinion (item 22) is
connected to motor shaft through a flexible coupling (item 23) which helps in
reducing transmission of vibrations from axle to motor. The gear wheel (item 24)
housed in a gear case (item 25) is directly mounted on bogie axle.

TECHNICAL SPECIFICATION OF THE TRACTION MOTOR IN
ACCORDANCE WITH THE INVENTION:
It is a 3 phase, star connected, 4 pole, self-ventilated, squirrel cage induction
motor without outer frame and mounted directly on the bogie transom. The
traction motor employs class 200 insulation scheme to with stand higher
temperature rise in service.
The traction motor of the invention is an especially designed motor for standard
gauge high power underground metro railway and EMU application which can be
used for broad gauge application also. The motor is supplied with IGBT based
variable voltage variable frequency supply to achieve precise speed and torque
control. Four motors are used per motor car of train.
RATING:
Continuous Rating : 1050 V, 150 A, 2190 RPM, 230 KW
Type of cooling : Self cooling
Class of insulation : Class 200

ESSENTIAL FEATURES:
■ Machine conforms to I EC 60349.
■ Class -200 insulation on Stator coils.
■ VPI of wound stator with high temperature class solventless silicone resin
■ Frameless structure
■ Fully suspended in bogie
■ Support arrangement for overhang portion of stator coils
■ Silver alloy induction brazing of rotor bars with short circuit ring
■ Temperature sensor for monitoring of temperature rise
■ Speed sensor for precise speed control
■ High power to weight ratio
■ Suitable for standard and broad gauge application
■ Stator and rotor core are built from high quality electrical grade sheet steel
laminations.
■ Ventilation holes are provided in stator and rotor core for better cooling.
■ Rotor has only one aluminium fan mounted at DE side and dynamically
balanced.
■ A terminal box is provided to facilitate the cable connections.
■ Power transmission is through a flexible coupling so as to reduce
. transmission of vibrations from axle to motor

WE CLAIM:
1. A frameless, fully suspended, self-ventilated three phase AC traction motor
for EMU and metro application, comprising :
- a stator core built from steel laminations insulated from each other, held
together under pressure between stator end chambers at both sides and
welded with four rectangular steel bars;
- a plurality of double layer LAP wound stator coils, having single parallel path,
housed in slots of stator core;
- a rotor core built from steel laminations insulated from each other assembled
under pressure on shaft between rotor end plates;
- multiple copper bars of half round rectangular cross section, inserted in each
slot of the rotor core and brazed together at both the ends with
short circuit rings.
- an aluminium fan mounted on shaft at driving end of the motor;
- a terminal box welded at top of the stator core at non-driving end side;
- end shields spigoted and bolted to said stator end chambers at both the
ends; and
- roller bearings at driving end and ball bearings at non-driving end provided
with labyrinths to prevent contamination of lubricants by dirt and moisture.
2. The AC traction motor as claimed in claim 1, wherein the stator is provided
with bogie fitting nose and fitting seat, opposed to prior art mounting on
wheel axle, and having holes for mounting the motor on bogie transom with
bolts.

3. The AC traction motor as claimed in claim 1, wherein the dimensions of the
motor matches the boundary limits of standard gauge traction applications.
4. The AC Traction Motor as claimed in claim 1, wherein class 200 insulation
system is employed in stator winding and temperature rise limits of the stator
and rotor are in accordance with IEC-60349.
5. The AC Traction Motor as claimed in claim 1, wherein star connected, four
pole stator windings are employed along with heat sealed polyimide covered
copper conductors.
6. The AC Traction Motor as claimed in claim 1, wherein overhang portion of
stator coils is supported with epoxy rings at both the ends to prevent damage
to the stator coils due to vibration in service, the epoxy rings being tightened
with support clamps screwed to stator end chambers at both the ends.
7. The AC Traction Motor as claimed in claim 1, wherein axial ventilation holes
are provided in the rotor as well as in the stator laminations for cooling.
8. The AC Traction Motor as claimed in claim 1, wherein air inlet arrangement is
provided on top of said NDE side end shield and openings are provided in the
DE side end shield for air exit.
9. The AC Traction Motor as claimed in claim 1, wherein the motor exhibits
continuous rating of 230 kW at AC power supply of around 1050 V, 150 A
and speed of approximately 2190 RPM.

10. The AC Traction Motor as claimed in claim 1, wherein the motor is enabled
to variable voltage variable frequency controlled traction application.
11. The AC Traction Motor as claimed in claim 1, comprising temperature sensor
and speed sensor for monitoring of temperature rise and speed control of
the train.
12. The AC Traction Motor as claimed in claim 1, wherein the pinion is
connected to rotor shaft through a flexible coupling.

ABSTRACT

The invention relates to a frameless, fully suspended, self-ventilated three
phase AC traction motor for EMU and metro application, comprising : a stator
core built from steel laminations insulated from each other, held together
under pressure between stator end chambers at both sides and welded with
four rectangular steel bars; a plurality of double layer LAP wound stator coils,
having single parallel path, housed in slots of stator core; a rotor core built
from steel laminations insulated from each other assembled under pressure
on shaft between rotor end plates; multiple copper bars of half round
rectangular cross section, inserted in each slot of the rotor core and brazed
together at both the ends with short circuit rings; an aluminium fan mounted
on shaft at driving end of the motor; a terminal box welded at top of the
stator core at non-driving end side; end shields spigoted and bolted to said
stator end chambers at both the ends; and roller bearings at driving end and
ball bearings at non-driving end provided with labyrinths to prevent
contamination of lubricants by dirt and moisture.