Electrical Engineering - Rail Transportation
3. Prior Art
3.1 Background
Rail coaches are generally provided with electrical power for lighting and cooling fans.
With the developments in technology and to improve passengers' comforts and
conveniences, provisions are being made .to operate air-conditioners, and pantry
equipment like refrigerators and ovens, as will. Such electrical power requirement are
termed as 'utility or hotel load' and is sourced either from a Captive or Self Generation
(SG) system of the coach or from a Head-on-Generator or an End-on-Generator (EOG),
with such system connected to a group of coaches of the train.
Complete.Patent Application
Invention: - Retrofitting of Self Generating (SG) System of Passenger Coaches
for Energy Conservation and Environment Protection
I ___ __- --= -- -- -
These systems are briefly described - as follows:-
3.1.1 Self generation System: Self Generation (SG) System is a conventional electrical
power generation system and is a captive source of electrical power for the respective
passenger coach. The system has an electrical generator coupled to the Axlels of the
passenger coach, along with complimenting batteries, inverters, pulley, belts, regulator
and battery box etc. Capacity of such system is selected as per the electrical power
requirement (1 x 4.5 kW per standard coach and 2 x 25 kW per AC coach, etc). 'This
system is used on all the conventional mail, express & passenger trains except the fully
AC trains.
3.1.2 End-on-Generation System: End on Generation (EOG) is a system used on air
conditioned(AC) trains of Indian Railways and dates back to 1960's or even earlier. This
system comprised a Diesel Generator (DG) set mounted inside a dedicated coach termed
as Power Car. Such DG set provides electrical power to Air-conditioned Coaches and
Dinning & Pantry cars etc. of such trains. In technical term, the power generated by DG
sets is utilized for hotel load of the train.
Depending upon the requirement of Hotel Load, the number of EOGIs provided to such
trains can be one or two. However, with the increasing popularity of AC trains,
provisioning of two EOGs for each train has become a common practice.
3.1.3 Head-on-Generation System: ~ead-on- en era ti on system is a very much prevalent
system of meeting the utility load requirement of passenger trains in many railways the
world over and has been recently introduced in India too. . .
. . .
Complete Patent Application
Invention: - Retrofitting o'f self ene era tin^ (SG) System of Passenger Coaches
for Energy Conservation and Environment Protection
In this system, utility power is generated on conversion of traction power. This conversion
takes place in a dedicated winding provided in the transformer of the electric locomotive
attached to the rake(group of passenger coaches). In other words, the transformer of the
electric locomotive an additional winding provided for the purpose.
3.2 In context of Indian railways, SG and EOG systems are very much prevalent. The
&
third system, viz. HOG has been recently introduced for mccting the .ulility load
requirement of fully .air-conditioned trains like Rajdhani Express. In an ingenious effort,
surplus capacity of the auxiliary winding of the locomotive has been tapped for the utility
load. These two types of HOGS, are. referred to as 'Rajdhani' and 'Saptagiri' systems
respectively in the subsequent write-up.
As on date, utilization of electrical energy from the two HOG systems needs either an
individual or bulk converter to convert the single phase power to three phase.
3.3 SG System has the following basic components:-
3.3.1 Alternator - to generate electrical energy from the mechanical energy of moving
axles
3.3.2 Rectifiers - to convert AC power from Alternator to DC power
3.3.3 Automatic Voltage Regulator and Ripple Filter
3.3.4 Battery - for storage of electrical energy
3i3.5 Inverter - to covert DC power from Battery to AC power, three phase
3.3.6 Step-up Transformer or Pre-cooling ~ransformer - for stepping the voltage of
electrical power obtained from the inverter
In addition, there are components for safety and controls like switches and fuses etc.
Complete Patent Application
Invention: - Retrofitting of Self Generating (SG) System of Passenger Coaches
for Energy Conservation and Environment Protection
While the components from 3.3.1 to 3.3.4 are common to all passenger coaches, though.
their specifications are different; 3.3.1 to 3.3.6 form the part of utility power supply in
AC Coaches with SG System.
Fig.1 depicts such systems for an AC coach. ~omponentsfo r Non-AC coach identical
though of reduced capacity.
Note :- Sequencing of the components may not he exac.tly3.3.1 to 3.3.6,
4. Drawbacks of Prior Art
4.1 SG system is although the most prevalent utility power sources with the Indian
Railways but this system is highly techno-economically in-efficient in terms of cost of
operation and efficiency and hence there .would have been a quest for an efficient
alternative. -However, being a captive system, it imparts the advantages of flexibility and
versatility.
4.2 The EOG System is the widely used alternative and off late Indian Railways have are
conducting trials with HOG system.
4:3 Sourcing of utility power from HOG System is though the most efficient alternative
but its adoption/utilization needs extensive and/or expensive re-engineering of existing
coaches by way of individual or bulk converter. to convert the single phase power to three
phase before feeding the intended utilities .
Complete Patent Application
Invention: - Retrofitting of Self Generating (SG) System of Passenger Coaches
for Energy Conservation and Environment Protection
5. The Invention
5.1 Patent application submitted here-in is for modification/retrofitting of electrical ,
circuits of the existing SG Coaches of Indian Railways and is titled as :-
'Retrofitting of Self Generating (SG) System of Passenger Coaches for Energy Conservation
and Environment Protection'.
The modificatiodretrofitting suggested will enable the electrical equipments of the
passenger coach, otherwise operating on SG System; to operate on the single phase AC
power supplied by the HOG or TPC. without .any additional phase converterls (bulk or
individual).
Note :- The Traction Power Converter or TPC consists of electrical equipment assembled
tq draw electrical power from the traction line and render it suitable for' operation of , '
utilities of the passenger train to which it is attached withlwithout any further electrical
activity e.g. step-uplstep-down, rectificatiodinversion etc.
5.2 In this invention, characteristics of electrical power's input and output of various
components of the SG System are put to use, so as to yield an optimum system to meet
the Hotel/Load of the passenger coach.
5.3 The Invention c,an be applied in several ways to provide a traction power based
electrical power supply system for the utilities. For example:-
5.3.1 Substitute the electrical power from alternator by that of HOGITPC and this
arrangement will yield a Universal Power System which will work both on. electrified
and non-electrified tracks. This switch-over from Alternator to HOG/TPCYs electrical
power system could be automatic or manual.
Complete Patent Application
Invention: - Retrofitting of Self Generating (SG) System of Passenger Coaches
for Energy conservatidn and Environment Protection .
The single phase AC power from HOG/'l'PC is stepped down to match the specifications
of power output from the alternator and for this purpose a set of suitable transformers is
to be provided to yield 110 V AC. Though this electric power will be single phase but
once rectified, the rectified output will be 1 lOV DC and thus match the rectified output
of the alternator. Ripple content of the rectified single phase AC will be talcen care of by
adding capacitors/RC filters in the circuit.. S11c.h addition and electrical powel cublc
(IVCs) will need investment but this will be just a fraction of the entire SG System.
This arrangement is depicted in Fig. 2.
Such modificationlretrofitting imparts the utmost flexibility in operation as the system
will be suitable to meet the utility power requirement of the.respective coach on the
electrified as well as non electrified (mixed) tracks.
5.3.2 Step down the electrical power from HOGITPC and connect it to the rectifier unit
and proceed as statid in paragraph 5.3.1. Such an airangeme*t will make the alternator
redundant thus making the SG Coach lighter by about 1,500 Kgs.
This arrangement is depicted in Fig 3.1 .and the retrofitted power supply can be.termed as
Practical Power System because of its relevance to the operations.
While such coaches will be good for electrified tracks; their battery backup will take care
of power outages due to operational reasons, as also for short/complementing haulage on
non-electrified tracks.
5.3.3 Subject to the degree of confidence in accessibility'to traction power and its
availability, the .battery too can be replaced by much smaller one thus making the coach
still lighter by another 1,500 Kgs.
Complete Patent Application
Invention: - Retrofitting of Self Generating (SG) System of Passenger Coaches
for Energy Conservation and Environment Protection
This arrangement is depicted in Fig 3.2. ... ..
.!
Such an arrangement will yield the best values of savings in cost and environment
protection, and thus is termed as Optimal Power System. However coaches with such
retrofitting can be used only on electrified tracks.
6. Benefits of the Invention
The invention will find application in the SG System based coaches of passenger trains
being operated on electrified as well as electrified-cum-non-electrified tracks; in meeting
the utilitylhotel power requirements. It is expected to provide cleaner and cheaper
alternative source of utilitylhotel power to operate the utilities of passenger coaches and
will provide the following advantages:-
6.1 On electrified tracks with HOGITPC power system in operation:-
6.1.1 Higher energy efficiency vis-a-vis the original SG System; thus imparting the
benefits of reduced operating cost and environment pollution.
6.1.2 No drag on locomotive; thus releasing much needed power, otherwise locked up for
electrical power generation by the SG System.
6.1.3 Negligible or little cost of retrofitting.
6.1.4 Lower operating and maintenance cost of the retrofitted system.
6.1.5 In case of retrofitting for exclusive use on, electrified tracks, the cost of retrofitting
would be more than offset by the realization from disposal of redundant components.
6.2 On electrified as well non-electrified (mixed) tracks:-
Complete Patent Application
Invention: - Retrofitting of Self Generating (SG) System of'passdnger Coaches
for Energy Conservation and Environment Protection I
While on electrified partlsection of tracks,. the Universal Power System, which is
essentially a retrofitted SG System suitable for operation on mixed tracks; will yield the,
benefits stated in paragraph 6.1.1 and 6.1.2.
There will little or negligible additional cost while operating on non-electrified tracks.
6.3 Retrofitted coaches with Optimal Power System (as described in paragraph 5.3.3) are
although suitable only for exclusive deployment on electrified tracks, hut, will yield thc
best .results of savings in operating cost and environmental protection. These coaches
will also impart the advantage of their lighter weight, with savings in haulage cost as
well.
6.4 Retrofitted coaches as described in paragraph 5.3.2 i.e. with Practical Power
'System, although, are suitable for exclusive deployment on electrified tracks but will
permit operational flexibility with deployments involving on short/complementing nonelectrified
tracks as .well. The yields in operating cost and environment protection will
only be little lower than those with Optimal Power System.
7.1 The invention will find application on the coaches of passenger trains being operated
on electrified as well as electrified-cum-non-electrified (mixed) tracks; in meeting the
utilitykotel power requirements of passenger coaches.
7.2 The envisaged retrofitting is simple, quick and inexpensive; and thus can be
implemented quickly without straining the resources.

I claim that Patent application submitted here-in is for modificatiodretrofitting , of
electrical circuits of the existing SG Coaches of Indian Railways and is titled as :-
' 'Retrofitting of Self Generating (SG) System of Passenger Coaches for Energy Conservation
and Environment A.L "1 Protection'. -1 Xf The modification/retrofitting suggested will enable the electrical equiya.lenls of the
passenger coach otherwise operating on SG System, to operate on the single phase AC
power supplied by the HOG or TPC without any additional equipment like phase
converterls (bulk or individual).
APT In this. invention, characteristics of electrical power's' input and output at various .
components of the SG System are put to use, so as to yield ari optimum system to meet the
HotelILoad of the respective passenger coach.
b2.I
9 W The Invention can be - applied in several ways to provide a traction power based
electrical power supply system for the utilities. For example:-
8.3.1. Substitute the electrical power 'from alternator by that of HOGITPC (suitably
stepped down). This arrangement will yield a Universal Power System which will work
both on electrified and non-electrified tracks. The switch-over from Alternator to TPC
could be automatic or manual. This arrangement depicted in Fig 2 imparts the utmost
flexibility in operation .with the retrofitted system capable of meeting the utility power
+\e quirement of the respective coach on the electrified as well as non-electrified tracks.
3~ Remove the alternator, and connect the stepped down single phase electric power
from HOGITPC to the rectifiers as depicted in Fig 3.1. The so retrofitted arrangement, rdd 5 -9 <->
.'. .
. >." l'
Complete Patent Application
Invention: - Retrofitting of Self Generating (SG) System of Passenger Coaches
for Energy Conservation and Environment Protection
termed .as Practical Power System; will make the respective coach lighter and yield even
better numbers on energy conservation and environment protection.
Though coaches with Practical Power System are suitable for electrified tracks but. will
permit limited operational flexibility with deployments involving short/complementing
non-electrified tracks as well.
-4 -.
In addition to doing away with the alternator, substitult: the battery with a smaller
one. The resultant retrofit, termed as Optimal Power System will yield even better energy
1 efficiency and pollution control values: However coaches with such retrofitting could be
i
I used only on electrified tracks.
This arrangement is depicted in Fig 3.2.
ZYb
5 WRetrofitting, envisaged in the Invention, provides Techno-economically viable
alternatives with little or no investment.
Ji4 The invention will yield the following advantages:-
86'1 On electrified tracks with HOGITPC power system in operation:-
I
8 x 1 Higher conversion efficiency vis-a-vis the original SG System with savings in
energy and operational cost and reduced environmental pollution.
8-Tf.2 No drag on locomotive; thus releasing much needed power, otherwise locked up
. for electrical power generation by the SG System.
d . 3 Negligible or little cost of retrofitting and has quick pay-back.
8 p Lower operating and maintenance cost of the retrofitted system.
Complete Patent ~ppiication
Invention: - ~ e t r o f i t t i nof~ S elf Generating (SG) System of Passenger Coaches
for Energy Conservation and Environment Protection
9.1 Patent application titled 'Retrofitting of Self Generating (SG) System of Passenger
Coaches for Energy Conservation and Environment Protection' envisages
modificatiodretrofitting of electrical circuits of the existing SG Coaches of' Indian
Railways so as to yield an optimum system to meet'the Hotel Load or utility Power
requirement of passenger coaches in Indian Railways.
9.2 In this invention, characteristics of electrical power's input and output at various
components of the SG System are put to use and the rnodificatiodretrofing, so
suggested; will enable the electrical equipments of the passenger coach, otherwise
operating on SG System, to operate on the single phase AC power supplied by the HOG
or .TPC without any additional phase converterls (bulk or individual).
Addition of Capacitors or RC filter is envisaged to take care of higher ripple content of
rectified single phase AC power.
9.3 The Invention can be applied in several ways to provide a traction power based
electrical power supply system for the utilities. For example:-
9.3.1 Substitute the electrical power from alternator by .that of HOGITPC and this
arrangement will yield a Universal Power System which 'will work both on electrified
and non-electrified tracks (Fig 2).
9.3.2 Remove the alternator and connect the stepped down single phase electric power
from HOGITPC to the rectifiers (Fig 3.1). The so retrofitted arrangement termed as
Practical Power System; will make the respective coach lighter with even better numbers
on energy conservation and environment protection.
Complete Patent Application
Invention: - Retrofitting of Self Generating (SG) Sfstem of ~ a s s e n ~ e r ~ o a c h e s
for Energy Conservation and Environment Protection
Though coaches with Practical Power System are suitable for electrified tracks but will
permit limited operational flexibility with deployments involving shortJcomplementing
non-electrified tracks as well.
9.3.3 In addition to doing away with the alternator, substitute the battery with a smaller
one (Fig 3.2). The resultant, retrofit, termed as Optimal Power System will yield even
better energy efficiency and pollution control values. However coaches with such
retrofitting could be used only on electrified tracks.
9.4 The invention is expected to help provide cleaner and cheaper alternative source of
utilitykotel power to operate the utilities of passenger coaches.
9.5 Modifications/retrofitting envisaged in the Invention provide Techno-economical .
alternatives with little or no investment and can be implemented quickly.