N KASHINATH
CSTE/P/S.RLY
TPWS PROJECT
Provided on Chennai Central/Chennai
Beach - Gummudipundi section of
Chennai division
Section length- 50 RKMs
Date of commencement- 24.02.05
Date of commissioning- 02.05.08
Total EMU rakes covered- 41 rakes
TPWS BENEFITS
 Ensures safe movement of trains under its
supervision
 Prevents over-running of the movement
authority (MA)
 Automatically brings the speed of train
within permitted limits in case of over
speeding
 Prevents train from entering danger zone
if the driver fails to control while
approaching a ‘RED’ signal.
TRACK-SIDE EQUIPMENT LAYOUT DIAGRAM
Note
JB-Balise Junction Box
LEU-Lineside Electronic Unit
Not to scale
Existing Signal
LEU
Cabinet
Existing
Signal
Location
Box
A
Infill Balise
CO
Data Cable
JB
e
e
JB
Fixed
Balise
e
Switchable
Balise
ON BOARD EQUIPMENT LAYOUT DIAGRAM
OBC-On Board Computer
BTM-Balise Transmission Module
DMI
On BoardCubicle
OBC
BTM
Wheel
Sensor
Brake
Valves
JB
JB
JB-Junction Box
Wheel
Sensor
Antenna
RE-TRAINING OF MOTORMEN
• After commissioning a second round of
training organised for improving their
confidence
• New motormen were also covered
• Operating instructions of TPWS to
motormen revised and made more
comprehensive
PERFORMANCE MONITORING
 Ansaldo staff stationed at both ends of the
section
 To ensure switching ON of TPWS
 Monitoring condition of TPWS at
commencement and end of journey
 Motormen recording en-route failures in the
EMU log book for onward transmission to
TPC.
FAILURE ANALYSIS
• On-board computer logs periodically
downloaded
• Logs analyzed using specially
developed sorting software
• Problem noticed on Track-side and Onboard system solved to the extent
possible
• Track-side system became fully stable
ON-BOARD PROBLEMS PENDING
RESOLUTION
 On-board system sometimes not booting
 System Failure (SF) sometimes while
booting
 SDMI on the run sometimes going blank
 Brake application due to speed bouncing
on SDMI
 Brake application in the non-driving rear
motor coach
MITIGATING UNRESOLVED
PROBLEMS
• Experts called from Ansaldo France,
Australia, Italy and Hong Kong
• They carried out detailed observations
in field
• Error logs of OBC studied
• Error logs sent to their countries for
analysis by specialists
CAUSES IDENTIFIED
 BTM-Antenna communication failure
 Error in Train Interface Unit (TIU)
 Error in Odometric (speed sensing)
system
 Back EMF from Electro Pneumatic (EP)
brake relay and solenoid valve coils
 Bugs in SDMI software and hardware inadequacies
 Rear coach on-board system getting shut
down during run in Sleep Mode
BTM-ANTENNA COMMUNICATION
FAILURE
• Due to antenna impedance mismatch
• Standing Wave Ratio (SWR) found
more than the tolerance limit of 1.2 to
1.4
• Interference from EMI
CORRECTIVE ACTION
• Antenna protection cover modified
• BTM to Antenna Tx/Rx cables shielded
with copper braids firmly connected to
body
• PROFIBUS and CTODL cables between
OBC & BTM shielded with copper
braids
• BTM configuration files modified
TRAIN INTERFACE UNIT ERROR
• Communication problem between
CBOP and MTORE cards in OBC
• Noise/Ripples in the 110V DC supply to
OBC from the EMU battery
• Causing intermittent on-board system
failure
CORRECTIVE ACTION
Cables between CBOP and MTORE
cards changed to screened twisted pair
cables
 Power filter provided at the input of
110V DC to OBC
All OBC rack wiring changed as per
modification plan sent by Ansaldo,
France
ODOMETRIC SYSTEM ERROR
• Interference from EMI
• TPWS traction control relay generating
wide spectrum of noise
• High resistance between EMU body
and the bogie
CORRECTIVE ACTION
Cable between OBC and Speed sensor
shielded with copper braids firmly
connected to body
TPWS traction control relay shifted
outside OBC cubicle
EMU body to bogie firm connection
provided
BACK EMF FROM EB VALVE AND EP
RELAY COILS
• EB and SB relays found affected by
EMI
• Back EMF of EB solenoid valve coil
and EP brake relay coils found high
• Problem became more acute during
braking
CORRECTIVE ACTION
• EB solenoid valve coils terminated with
180/200V MOVRs
• EB & SB relay bodies firmly connected
to EMU coach body
• Surge suppressor provided at the EP
brake coil
BLANKING OF SDMI ON RUN
Basic hardware and software
inadequacies
Residual bugs in SDMI software
Interference from EMI
Ripples in 110V DC input power supply
CORRECTIVE ACTION
 SDMI software upgraded to next higher version
v1.6.4
 OBC-SDMI communication cable connector
cover changed from plastic to metallic
 OBC-SDMI and SDMI power supply cables
shielded with copper braids firmly connected
to coach body
 Power filter provided at the SDMI-110V DC
input point
REAR COACH ON-BOARD GETTING
SHUT DOWN ON RUN
• Due to errors in various subsystems
the on-board gets shut down.
• On-board shutting down activates EB
command
CORRECTIVE ACTION
• Brake interface circuit modified to
bypass EB command in Sleep Mode.
• Prevent the On-Board in sleep mode
from getting shut down by the
modifications discussed earlier.
PLAN OF ACTION FOR
MODIFICATIONS
• One by one motor coach to be taken
OFF service & handed over to Ansaldo
• Initially 4 coaches were got modified
• Their performance closely monitored
for 4 weeks
• Found substantial improvement in
performance of these 4 coaches
PLAN OF ACTION FOR
MODIFICATIONS…contd
Balance coaches also decided to be
modified
Ansaldo initially took 3-4 days for
modifying a coach
Ansaldo asked to reduce it to 2 days by
working in two shifts
17 coaches modified till date
EXPECTATIONS
 Most of the coaches are expected to be
modified by 31.05.2010
 Improved performance levels expected to
meet the operational requirements
 Could lead to acceptance of TPWS for
safe running of EMUs
 Top management requested to be patient
for the results