Friday, May 31, 2013

What are new developments in locomotives?

Q) Where we got the locomotive technology from?
Ans):-Transfer of technology (ToT) from ABB (Switzerland, Germany & Australia).  Then ToT partners developed in India with an aim to indigenize the major equipments.
Indian Railway obtained Technology from ABB, for indigenous manufacturing of two types of 3Ф electric locomotives   viz. WAG9 freight and WAP5 passenger class through ToT agreement signed in 1993. Based on the know how,  the new variants WAP-7 and WAG9H class locomotives were produced. Serial production of WAP-7 was taken up from 2000 and that of WAG-9H from 2011.
Indigenization of 05 major equipment viz. Traction Motor, Transformer, Traction Converter, Auxiliary Converter and Central Electronics along with other items of the loco has been done.

Q)Why are IGBT based Converters used for in Locomotives?
Ans) 3-phase locomotives in Indian Railways are equipped with GTO based converters. GTO based converters have disadvantages such as poor Slip/slide control due to group drive, higher switching losses, complex snubber circuit and above all obsolescence of GTO. Therefore,  IGBT (Insulated Gate Bipolar Transistor) based converter is being used.
First locomotive with IGBT based Traction Converter was rolled out in December 2009 and first locomotive with IGBT based Auxiliary Converter was rolled out in October 2010. For FY 2012-13, about 40 locomotives with different mix of converters are expected to be rolled out with IGBT based converters. As per Railway Board’s directives 70% of 3-ф locomotives with IGBT based converters have been targeted  to be rolled out in FY 2013-14.

Q)  What is  Open Platform Control System for Vehicle Control with TCN compatibility?

Ans):Present vehicle control system of 3-phase locomotive is based on ABB proprietary protocol MICAS-S2, which is of 1980s vintage. Thus, the system is vendor specific and has disadvantages such as difficulties in modification/upgradation due to specific compatibility of available hardware with software. Further, being an old system hardware architecture is based on old slow processors and components.

Open control VCU works on published protocol based on IEC-61375, also known as TCN (Train Communication Network). Application Software coding is based on PLC languages complying IEC-61131.  Due to use of high speed processors, there are less number of processor cards, faster signal processing and implementation of latest algorithm for signal processing. No special tool is required for downloading the software in locomotive and troubleshooting.

First locomotive with TCN compliant VCU was rolled out from CLW in June 2011.

Indigenous development of TCN compatible vehicle control system has been tried. First locomotive with indigenous TCN compliant vehicle control system has been dispatched to ELS/TKD in December 2012.

Q) What is the status of   Indigenous development of IGBT based 3- Phase propulsion equipment?

Ans):CLW has placed supply orders on M/s Medha Servo Drives Pvt. Ltd. for indigenous development of the 3-Phase propulsion equipment. The prototype supply is expected by May 2013.

Q) What is Hotel load Converter?

Ans):Diesel power cars used in Rajdhani/Shatabdi trains consume ever depleting fossil fuel accompanied by emission of air and sound pollution.

Hotel load converter utilizes pollution free and cheaper power from OHE. It has highest reliability as compared to SG and EOG system due to reduced number of generating equipments.  Cost saving per loco per year on account of fuel only is estimated to be Rs. 50 Lakhs and thus return on investment can be achieved in less than three years.

First locomotive with Hotel load converter is running under commercial service in Kalka Shatabdi since February 2011.

Q) What is Active Speed sensor with Doppler radar on 3- phase locos:
Ans):The 3-ф loco is a group drive system. Slip (Slide) control algorithm is based on comparison of the bogie wise filtered lowest(highest) axle speed with the highest (lowest) axle speed in traction (braking) mode. In case of wheel slip/slide in a bogie this algorithm doesn’t give correct reference speed. The problem is particularly severe in case of slipping/sliding of all axles in a bogie.

Speed sensor with Doppler radar has been developed for 3-phase locomotives. In this system, actual ground speed is measured by radar which is taken as the reference speed. The loco slip/slide is detected with respect to the ground reference speed. This will result in better slip/slide control.

05 prototype units of Speed sensor with Doppler radar Speed sensor with Doppler radar have been installed in locomotives and trials have been conducted under ELS/GMO.

Q)    What is wireless remote control of slave locomotives In a long haul train:

This system, popularly known as Locotrol, has been developed to handle heavier and longer trains with locomotives distributed over the length of the train. The Master locomotive (one which has the loco pilot) controls other locomotives through the RF wireless link in distributed power (DP) consists. This enables optimized distribution of traction and braking action, faster acceleration and deceleration leading to improved throughput and faster cycle times, reduced crew need and increased overall tonnage hauling capabilities.

The first pair of 3-phase WAG-9 locomotives with RRCS (Radio Remote Control System) is running in commercial service under ELS/Tata. CLW has also developed wireless MU coupler system for microprocessor based AC tap changer locomotive. The first pair of locomotives with this system is running under ELS/KZJ.

Q)   What is  Hurth Coupling (Alternate Drive Gear Assembly for WAP5) ?
Ans) :There were reliability issues of the presently used Hurth coupling by way of improved design of the transmission system.  Hurth coupling has a rubber membrane where as Alternate Drive Gear system has combined curved tooth coupling/ring disc    coupling, having no rubber membrane. First locomotive with alternate drive gear system for 160 kmph service speed has been dispatched to ELS/Vadodara in Decemder 2012.
First locomotive with alternate drive gear system for 160 kmph service speed.

Q)Can we operate WAP-5 in multiple consists?

Ans): Yes !This  enables running of 24 coach trains at a speed of 160 kmph. WAP-5 Multi Locomotive enables operation of slave loco, without raising its pantograph, taking OHE power from master locomotive through HV cable.

Successful trial with modified loco software has been carried out under NR. WAP-5 loco Nos. 30059 & 30060 with MU system has been dispatched to ELS/BRC in February 2013.

Q)Can we operate WAP-5 in multiple consists?
Ans):   Other developments are:

  • Composite Converter: There are space constraints in WAP-5 locomotive for installation of hotel load converter. As the IGBT based traction converters have smaller size vis-à-vis GTO converters, CLW has planned to develop the composite converter housing both IGBT traction and hotel load converter in the same cubicle for WAP-5 locomotives. The hotel load inverter shall be fed through common DC link.
  Development of drive gear system to increase the speed potential of WAP-5 up to 200 kmph is in its advanced stage and is likely to be installed by September’13.
  Development of common software across all the variants of locomotives.


  Turning out first Electric loco with IGBT based Traction Converter in December 2009.
  Turning out first Electric locomotive with IGBT based complete Propulsion system in July 2012.
  Turning out first locomotive with Hotel Load Converter in June 2010.
  Turning out first Electric loco with Open Control VCU in October 2010.
  Turning out first 3-Phase Loco with Locotrol system in January 2011.
  Turning out first Microprocessor based conventional locomotive Locotrol system in July 2012.
  Turning out first locomotive with indigenous VCU in December 2012.
  Turning out first WAP-5 locomotive with advanced alternate gear drive system in December 2012.
  Installation of prototype Doppler radar based slip/slide control system for improvement of slip/slide performance of 3-Phase locomotive in December 2012.
  Porting of existing MICAS-S2 based loco software into IEC 61131 compliant Functional Block Diagram based PLC Language for TCN compliant VCU.
  Completion of 3-D modeling of 3-Phase locomotives.
  Development of Improved 10.4” Color Driver Display Unit.
  Development of Remote Diagnostic System.
  Development of Active speed sensor.
  Indigenous Development of GUL ASIC for Gate drive unit of traction converter.


  1. What is HV Cable? As far as i know UIC cable does the job of MU ing two loco's.

    1. HV cable essentially means High Voltage cable here. UIC cables only carry low voltage control signals. HV cable will carry 25 kV AC for powering the slave locomotive and thus avoid the need of having the slave locomotive use a pantograph. This is important for high speeds where multiple pantographs will introduce heavy turbulence in the catenary, leading to failures.

  2. Amtrak uses two AEM7 electric locomotives in NE corridor for Acela Regional. They travel at 125 mph, i.e. 200 kmph.

    At that speed, there is no known issue about turbulence in OHE.

    European TGV travel at significantly higher speeds where turbulence becomes an issue.

    IR is nowhere near 200 kmph as of now.

  3. From your post i got answers of many questions,some concepts are also clear now..thank you for posting..
    coupler manufacturer in India

    1. Thanks. Railways is committed towards adding value.

  4. IGBT is an effective device for all types of power supply device it can be brought from various buyers.

  5. Does the new igbt technology use snubber circuits..? If no..why?? Thanks in advance!