traction ohe metro

1. 25 KV Flexible OHE at Viaduct and Yard.
0

3. OHE ASSETS OF MAIN LINE
Sr. No Item
MANSAROVER TO SINDHI CAMP
ROCS SECTION
1 Date of commissioning - -
2 Track KM 18.689246 529.854
3 Contect wire 23.627836 1.067
4 Massenger Wire
24.48162
-
5 OPC 19.54 1.13
6 BEC 19.36 1.13(TEW)
7 RC 18.5 1.13
8 IB 20 2
9 Cantilever 762 -
10 Section insulator 9 -
11 Cross Over 2 -
12 Gas ATD 36 (A-8,B-5,C-23) -
13 BWA ATD - -
14 Over lap 23(IOL-13, UIOL-10) 1(UIOL)
15 Turn Out 3 -
16 Isolator 10 -
17 8X8 Mast 470 -
18 B-series Mast(7.00) 102 -
B-series Mast(8.50M) 10 -
19 PORTAL 9 -
20 RSJ 22 -
21 DA 80 80

4. OHE ASSETS OF DEPOT
Sr.No. Item YBD
1 Date of commissioning -
2 Track KM -
3 Contect wire -
4 Massenger Wire -
5 OPC -
6 BEC -
7 RC -
8 ITL -
9 Cantilev
er 295
10 Section insulator 27(galland11,rail 16)
11 Cross Ov
er 1
12 Gas ATD 0
13 BWA ATD 28
14 Ov
er lap 17(UIOL)
15 Turn Out 21
16 Isolator 19 (SS-15,DM-4)
17 8X
8 Mast 69
18 B-series Mast 39
19 Two Track Cantilev
er 6(TTC)
20 portal BFBU 18
21 FP B-200 24
22 RSJ 8X
6 22
23 DA 6X
6 40
24 Earth Pit 71

5. OHE system adopted in JMRC
• Cantilever Assembly
• Mast & Implantation
• Steady Arm & Encumbrance
• Size of Contact wire and Tension in OHE.
• Droppers and Jumpers.
• ATD
• Section Insulator
• Neutral Section arrangement.
• Earthing and Bonding
• Return Conductor and Booster Transformer.
• OHE Parameters, OHE Sectioning, OHE Spares and T&P, OHE
Inspection & Maintenance Vehicles
• OHE Inspection & Maintenance Schedules
4

6. STAY ARM
Stay Arm comprises of dia 38 mm (Small) size tube and an adjuster at the end to keep the bracket
tube in position. It is insulated from mast by stay arm insulator.
Bracket tube comprises of dia 49 mm and insulated by bracket insulator. Catenary is supported
from this member by catenary suspension bracket and catenary suspension clamp.
Register arm comprises of dia 38 mm tube to register the contract wire in the desired position with
the help of steady arm.
Steady arm comprises of dia 25mm BFB section made of aluminium- alloy to register the contact
wire to the required stagger and to take the push up of contact wire. It is always in tension.
Bracket tube
Register Arm
•Steady arm.

7. ROCS in Tunnel and Underground Section.
6

8. ROCS Cantilever different Part
7

9. Transition element from Flexible to Rigid OHE
The termination of the contact wire coming from the flexible catenary is terminated
in the ROCS through a special come along clamp inserted on the last conductor rail

10. Details of Mast Used in JMRC
SN Type of Mast Dimension Height Remarks
1 BFB ( Broad Flange
Beam )
8’’X8’’ 6.2 m Used in single
cantilever location of
viaduct
2 BFB ( Broad Flange
Beam )
8”X8” 9.5 m Used at Graded
section / Depot.
3 RSJ (Rolled Steel
Joist)
8”X6” 6.2 m Used at BT location
4 RSJ (Rolled Steel
Joist)
8”X6” 9.5 m Used in Depot for
mounting isolators.
5 B – 175 175X300 mm 6.2 m Multiple cantilever
Location, Anchor
location.
6 B – 200 200X300 mm 8.5 m Switching posts for
cross feeders 9

11. Type of Mast

12. Implantation
• The horizontal distance from the nearest face of traction mast to the centre line of
the track . Track gauge =1435 mm
• Centre of track = 717.5 mm Say 71.75 cm
• hence put tape (non metallic) at 71.75 cm at inner edge of track & stretch till it reaches to
the nearest face of the mast. The measured distance at face of the mast is implantation of
the mast Centre Line
of the Track
Face of the
Mast

13. Steady Arm
• In JMRC bent steady arms are used for better
performance in dynamic condition and it
ensures better current collection at register
point of cantilever.
12

14. Encumbrance
• The axial distance on vertical plane between the
Catenary and the contact wire at support the
encumbrance shall normally be 0.90 M
.
Encumbrance

15. Size and tension of Contact and Catenary wire
• Contact wire of 150 Sq mm hard drawn copper conductor is used in JMRC
in contrary to 107 Sq mm Copper in IR.
• The reason behind using of larger cross section area is that 1200 kgf
tension is applied in both contact and catenary wire for better current
collection. Whereas in Railways 1000 kgf tension is used.
• The larger cross section area of contact wire also increases the breaking
load of contact wire.
14
Contact Wire Splice Catenary Wire Splice

16. Droppers
• In JMRC 12 mm bronze flexible cables used as
droppes in contrary to 5 mm hard copper wire
with loops in Indian Railways.
• The risk of dropper breakage due to sparking
in loops in IR has been resolved by using
flexible crimped type droppers in JMRC.
15

17. Droppers in JMRC
16

18. Jumpers
• Fit and Forget Type of Jumpers used in OHE to
maintain electrical continuity and ensure equi
potential within spans, across insulated overlaps,
crossovers and in the sectioning posts.
• The advantage of crimped jumper is that it ensures
good contact thereby reducing contact resistance in
turn reducing the chances of localize heating. Less
maintenance is required.
17

19. Jumpers Arrangement
G Jumper
18

20. In span jumpers
• In JMRC 26 sq mm, in span jumpers are
provided in every 200 m between contact and
catenary for current distribution in contrary to
65 sq mm, jumpers in every 350 m in Indian
Railway.
• By increasing no. of jumpers in each tension
length the distribution of current between
Contact and Catenary improves.
19

21. In span jumpers in JMRC
20

22. Regulating Equipment (ATD)
•
• A device for maintaining the tension of OHE
conductors constant under all ambient
temperature conditions. It has two type.
• 1. Balance weight type
• 2. Gas type
5 PULLEY TYPE
Balance weight ATD

23. Gas type ATD
For critical locations where sufficient room is not available for counter weight
installation , Due to less travelling distance available for movement of counter weight and to
avoid falling of weight on road due to snapping of rope, Gas Type ATDs are used in JMRC
Gas Type ATD is proposed to be used. In gas tensioners (Gas ATD) regulation is
achieved by cylinder piston arrangement filled with the pressurized Nitrogen (N2) gas.
In this arrangement piston is fixed on mast and cylinder is movable and is connected
to OHE wires. Three type of Gas ATD’s are available as per half tension length. Total 41
nos GATD are in service in JMRC
A) Type ‘A’ - Suitable for tension length up to 297 m
b) Type ‘B’ - Suitable for tension length up to 468 m
c) Type ‘C’ - Suitable for tension length up to 721 m

24. Construction and working of GATD
23

25. Section insulators
• In JMRC light weight section insulators are
installed to achieve spark less current
collection in high speed and can be used in
main lines. In Indian Railway generally heavy
section insulators are used in only crossovers.
• Provision of SI in main line give the flexibility
for installing switching posts at will.
24

26. Section insulators in JMRC
25

27. Neutral Section
• In JMRC magnets are used at before and after
of Neutral Section for proper opening and
closing of VCB’s before and after neutral
section. In Indian Railways driver of the trains
normally opened the VCBs at DJ open board
location.
• NSCZ boards also provided to rescue the trains
in case of train stuck at neutral section.
26

28. 27

30. SHORT NS

31. Design of NS(AF design)
R B

32. • PTFE rod gives larger Air gap causing almost
no chance of wrong phase coupling. This
reduces chance of damage to NS and
pantograph both.
• Mid point earthing further minimises coupling
of two different phases.
Advantages of Short Neutral sections

33. Earthing & Bonding System
• All viaduct is non conducting concrete structure. Hence, special earthing
arrangement has been provided.
• Overhead Protection Cable (OPC) on top of OHE network and Buried Earth
Cable (BEC) along track are run to provide complete earthing. All masts are
connected with OPC.

34. Earthing & Bonding System
• Every pier is provided with a non structural earthing bar (T-20). Earthing
terminal is provided at the top of earthing bar.
• All segments and track plinths are interconnected through jumpers.
• Plinth Jumpers are connected to Buried Earth Conductor at every 100 meter.

35. 34

36. 35

37. Return Current and Booster Transformer
 Simple 1x25 kV ac traction systems can produce inductive
interference in telecom lines and other equipment.
 Booster transformer system reduces that inductive interference.

38. Return Current and Booster Transformer
 Single system (ST): Return current system made by rails and buried
earthing cable (if it exists).
• The overhead catenary is fed electricity at 25kV AC (single-phase) from
traction substations which are positioned at frequent intervals
alongside the track. Current supplied by substations flows through
catenary to the rolling stock and returns through rails. In some cases,
this system also uses one buried earthing cable located along the track
and connected to the rails at regular intervals. In this way, return system
is made by rails and buried earthing cable.

39. Return Current and Booster Transformer
 Booster Transformer (BT) System: Return conductor close and
parallel catenary wire. Return conductor is connected to the rails.
• In this system there is a return conductor that is close to and parallel to the catenary wire.
• Return conductor is connected to the rails (and earthed).
• Periodically (every 2.5 km), there are breaks in the catenary where the supply current is forced to
flow through one winding of a booster transformer. The other winding is in series with the return
conductor. The 1:1 turn ratio of the BT means that the current in the catenary will be very nearly the
same as the current in the return conductor.
• Current that flows through the rolling stock goes to the rails but then up through a connecting wire to
the return conductor and through it back to the substation.
• Insulated rail joints are also provided -- this ensures that current flows in the rails only in the
particular section where the train is present. At all other places, the inductive interference from the
catenary current is nearly cancelled by that from the return current, thus minimizing the interference
effects. The problem of stray earth currents is also reduced.

40. Return Current and Booster Transformer

41. • A special rail bond
used to bridge an
insulated rail joint
in ac track circuited
sections in areas
equipped for
electric traction
.

42. Parameters of OHE in JMRC
SN Items Values
1 Height ( Elevated ) 5 m No Variation
2 Height ( Under Ground ) 4.318 m No Variation
3 Stagger (Straight) +/- 200 mm No Variation
4 Stagger (Curve) +/- 300 mm No Variation
5 Min. Clearance betw live parts
and structure (UG)
270 mm (Long time)
170 mm ( Short time )
Within limit
6 Min. Clearance betw live parts
and Bodies of vehicle (UG)
290 mm ( Long Time )
190 mm ( Short Time )
Within limit
7 Min. Vertical Clearance betw live
parts and Earthed structure or
Bodies of vehicle (Elevated)
320 mm ( Long Time )
270 mm ( Short Time )
Within limit
8 Min. Lateral Clearance betw live
parts and Earthed structure or
Bodies of vehicle (Elevated)
320 mm ( Long Time )
220 mm ( Short Time )
Within limit
41

43. Sectioning of OHE
SN Type Quantity Location
1 Total RKM 9.7 km ( El -9.438 km,
UG – 0.262 KM )
2 Elementary Section 14
1 Sub Sectioning (SS) 2 Mansaovar, Sindhi
Camp
2 Sub Sectioning and
Paralleling (SSP)
1 Vivek vihar
3 Feeding Post (FP) 3 Mansarovar, Depot,
Sindhi camp
4 Sectioning and
Paralleling (SP)
1 Civil lines.
42

44. Spares and T&P for OHE maintenance
SN Wing Major spares Major T&P Additional requirement
1 OHE All OHE spares like
different types of
conductor, jumpers,
cantilever assemblies,
Isolators, Masts, SIs,
etc. already procured
by JMRC.
T&P items like Earth
tester, multimeters,
Tirfors, pull lifts,
meggars, tool boxes,
crimping tools, slings,
D- sackles, discharge
rods, safety belts,
helmets, Contact wire
dia measuring devices,
height and stagger
gauges etc already
procured by JMRC.
Some items which was
left out in contract like
Gas ATD, BWA ATD,
Short neutral Section,
PG clamps, all nut bolts
etc and few spares and
T&P’s felt less in
quantity in contract are
under procurement.
43

45. Maintenance and Inspection Vehicles
Tower Wagon Emergency Vehicle

46. OHE Inspection & Maintenance
SN Activity Schedule Checking points
1 Foot Patrolling Fortnightly Foundation ( At Grade )
OHE mast and portals
Anchor
Bracket Assembly
Section insulator
Regulating Assembly
OHE Span
Isolator
RC & BT
Earthing
2 Section Insulator Monthly Cleaning of core insulators
Tightness of all nuts and bolts
Checking of Runners
Panto movement checking and balancing
3 Neutral Section Monthly Cleaning of PTFE rod.
Checking of Runners
Checking of balancing

47. OHE Inspection & Maintenance
SN Activity Schedule Checking points
3 Section Insulator
( Other than
Polluted Zone )
Quarterly Cleaning of core insulators
Tightness of all nuts and bolts
Checking of Runners
Panto movement checking and balancing
4 Gas ATD Half Yearly Tightness of all nuts and bolts
Measurement of X value and ramp extension
Cleaning of Ramp
Checking of Gas pressure.
5 BWA ATD Half Yearly Free movement of balance weight
Greasing if required
Checking of SS rope
Measurement of X-Y value and adjustment if
required.
6 Current collection Half yearly The points detected during current collection to
be attended on priority basis.

48. OHE Inspection & Maintenance
SN Activity Schedule Checking points
7 ST ,BT Insulator Half Yearly Cleaning of ST, BT insulator of polluted zone.
8 Cross over/TO Yearly Checking of height and stagger of mainline
OHE and T/O OHE.
Checking of sag in section insulator
Panto movement checking
Check bracket of obligatory mast.
9 Overlap Yearly Check height and stagger of IR and OR.
Check clearance of OHE.
Check jumper and PG
Check panto movement.
10 Cantilever Yearly Check and tight all nut bolt.
Cleaning of insulator.
Measurement of height and stagger.

49. OHE Inspection & Maintenance
SN Activity Schedule Checking points
11 Contact wire dia
measurement
yearly Contact wire dia should be taken in different
locations where wear rate is high. A register to
be maintained to check wear rate. Marking to
be done on locations for future reference.
12 Tree trimming Yearly Every year in January joint inspection to be
carried out with P Way to identify the trees
nearby OHE.
13 Kite, Thread / Bird
nest removal
Yearly Should be attended on priority basis as
observed during Foot plating and patrolling.
With special emphasize in bird nesting season
from April to September

50. OHE Inspection & Maintenance
SN Activity Schedule Checking points
14 POH 4.5 yr Cantilever : One complete cantilever in identified
polluted zone is to be replaced and its thorough cleaning
and detailed examination is done of its moving parts for
free movement and its rusted parts to take decision for
level of maintenance. Check all the Cantilever
component for cracks, rust and thread damage with a
magnifying glass. The crack fittings and damage threads
fittings should be discarded. Deteriorated GI fittings and
pipes should be repaired by using cold galvanized paint.
ATD : All regulating equipment(ATD) should be replaced
with the overhauled ATD. SS rope should be closely
examined for any damage to its strands. Ends of SS rope
is also to be reversed. X & Y values to be adjusted as per
temperature chart either by wire cutting or by adjuster.
Removed ATD is to be taken to workshop and petrol
cleaned and check for any rubbing mark on pulley block,
if any replacement to be done. All lubricating holes
should be free for passage of grease. Check for free
movement of bearing of pulley block. Grease should be
applied in the bearing by grease gun.

51. OHE Inspection & Maintenance
SN Activity Schedule Checking points
14 POH 4.5 yr Jumpers: Dismantle all jumper
connections. Check for broken/ damage
strands. Overheating or corrosion specially
at suspension clamps & BM flange
connection.
Contact and Catenary :a) Dismantle all
Jumper connections
b) Clean the conductors by emery paper, if
there is a sign of over heating.
c) Remove kink, if noticed
d) Check the height and gradient of contact
wire.

52. Inspection Schedule of Officers of
OHE installation
Inspection Supervisor Manager DGM GM ED
Foot patrolling
(full section)
Monthly Quarterly 6 monthly Yearly As & when
required
OHE Gang
(each gang)
With gang Monthly Quarterly 6 monthly Yearly
Cab/ Foot
plate
Daily Weekly Monthly Quarterly 6 Monthly
Tower Wagon Fortnightly Monthly Quarterly 6 monthly Yearly
Emergency
vehicle
Fortnightly Monthly Quarterly 6 monthly Yearly
OHE Depot Fortnightly Monthly Quarterly 6 monthly Yearly
Current
Collection
6 monthly 6 monthly Yearly Yearly As and when
required
51