Traction distribution

2. PLANING OF LAY OUT OF OVERHEAD
EQUIPMENT
Types of Overhead Equipment:
1- Conventional type OHE - Contact + Catenary
wire, Tension
1000 Kg. + 1000Kg
2- Tramway type OHE - Single wire without
Catenary, Tension
1250Kg.
[[1- Regulated OHE - 160 KMPH
2- Un-regulated OHE - 60 KMPH

3. Contact Wire: Hard Drawn Copper
Area/dia/condm dia -107 Sq.mm/12.24/8.25
Catenary wire: Cadmium Copper
Area/dia - 10.50Sq.mm/65mm
Droppers: In Span/Register arm/RRA /
Adjustable near Sec. insulator
• 7/5mm copper wire
• Inclined dropper – to hold register tube with
bracket tube -7 mm dia .
• First droppers from cantilever at 4.5 meters. Dia-
5 mm.

4. Jumpers:
• Cu stranded wire of 160/105/50 Sq.mm
• Carry current / equalize potential
“G” Jumper (105 Sq.mm) annealed copper
wire - In Un-isulated O/L.
“C” Jumper (50 Sq.mm) stranded copper wire
– To distribute current bet. Con. & Cat. wire
“F” Jumper (50 Sq.mm) stranded copper wire
– Provided on either side of isulated O/L.

5. Masts:-
• BFB - Good in resisting bending moment but
weak in twisting (6X6, 8X8)
• RSJ - Good in resisting bending moment as
well as in twisting 8X6
• Fabricated (K type) – Used where adequate
track center available
(K-100, K-125, K-150, K-175, K-200, K-225 & K-
250)
• TTC mast
• Concrete Mast

6. Portals:
• N type 10m to 20m Span Max 4 tracks
• O type 20m to 30m Span Max 6 tracks
• R type 30m to 40m Span Max 8 tracks
• P type In place of “N”type where track separation
is less.
• G type In place of “O”type where track separation
is less.
• BFB uprights and 3 leg special BFB portals can
also be used in exceptional cases where
track separation is less.

7. Foundations:
Side
bearing
Used in good consolidated hard soil,
Bearing prr. > 10000 kgf/sq.m
Side gravity Used where shoulder width is not
sufficient
Pure gravity Used in un-consolidated filled up soil,
Bearing prr. < 10000 kgf/sq.m
Pure gravity
for block
cotton soil
Used in black cotton soil
Dry BC-16500 kgf/sq.m
Wet BC-8000 kgf/sq.m
Portal foundations

8. Insulators:-
By type
• Porcelain Insulators / Hybrid insulators /
Composite insulators
By Usage
• Stay tube insulator / Bracket tube
insulators / 9-tonne insulator/ Suspension /
Disc Insulator / Pedestal insulator /
Polymn Long creepage insulators

9. Neutral Section
Provided to separate OHE of two adjoining
feeding post.
Conventional Neutral Section
• 41 meters in lengths.
PTFE type Neutral Section
• 5.163 meter ceramic beaded type
• 9.4 meter PTFE sleeve type .

10. Overlaps:
• Insulated overlap 500 mm gap
• Un Insulated overlap 200 mm gap
Clearances:
• Short time clearance 200mm
• Long time clearance 250mm
Schedule of dimensions:
• Normal Implantation 2.8(where formation
level
3.425m)/2.5 m
• Minimum Implantation 2.36 meters
• Implantation on platforms 4.75 meters.

11. Survey Before Electrification
Techno-Economic Survey:
• Assess the feasibility of Electrification on a
particular route.
• Availability of power supply.
• Suitability of the terrain and of the over line
structures.
• Availability of terminal / yards for change of
traction.
• Cost of the project.
• Financial viability of the investment based on
discounted cash flow method.

12. • Foot by foot survey
• Reconnaissance Survey
• Precautions during new wiring
• Final Checking
• Safety Checks
• Safety Certificates

13. Energizing New Line
• Clearance certificate from the contractor
regarding all men and materials removed.
• Joint Certificate by Sr.DEE’s of RE and open line
that all staff has been removed and warned.
• Certificate from S&T officers that their work has
been completed and OHE can be charged.
• Sanction of EIG for energisation is taken.
• Sanction of CRS is obtained.
• Certificate of clearance of DOT.

14. • After all formalities, the new line is charged in
presence of a senior electrical officer in following
sequence step by step
25 kV feeders from substation to feeding post.
Busbars of the feeding posts.
First sub-sector.
Second sub sector and so on
Confirmatory tests for proper operation of
protective relays should be carried out.

15. Principles of preparation of Layout
Plan
1-Electrical Clearance – A short time clearance
of 200mm & working clearance of 2m.
2-Wind pressure – Considered for design of
masts and determination of spans.
3-Span - Between 27 meters to 72 metes in steps
of 4.5 m as per requirement.
4-Masts, Portals, Heads spans and foundations
- Should be selected according to Employment
schedule

16. 5-Contact wire height –
 Standard contact wire height of 5.6 meters.
 Near over line structures minimum 4.92M. In
loco sheds 5.8M.
 At level crossings not less than 5.5M.
6-Stagger – + 200mm is maintained on
straight line and up to 300mm on curves.
7-Encumbrance – 1.4 m is adopted. Near
over line structures reduced up to 0.3M.
8-Droppers- As per droppering schedule for
a given span and encumbrance.

17. 9-Section Insulators- Axial distance between
the catenary and contact wire at section
Insulator location should not be less than 600
mm (450mm in case of single wire section
insulators)
• Stagger of the section insulator should normally
be zero. In no case it should exceed + 100 mm.
• Section Insulator should be located where
distance between centre line of two tracks is
more than 1.65m. If free end of the runners is
away from centre of turn 0ut, it can be reduced
to 1.45m .

18. 10-Jumpers - Different types of Jumpers to be
provided as discussed earlier.
11-Tension length
• The half tension length should be more than 750
meters. On curves, it should be reduced to
600M.
• Termination of anti-creep anchor avoided inside
the tunnels on bridge masts.
• Unregulated OHE, tension length of up to 2000
meters can be adopted on main lines as well as
curves .

19. 12-Anchor Restriction –
• Crossing of OHE of different elementary
sections in the anchoring span.
• Crossing of regulated and unregulated
equipments.
• Vicinity of signals, water columns.
• Back to back anchoring of two OHE on the same
mast.

20. 13-Location of overlap-
• Overlaps should be so located that ATD does
not come on platform.
• Insulated overlaps should be protected by stop
single.
• Feeding overlaps should be sufficiently away
from the stop signal.
• Span of the overlap should be such that at least
2 meter parallel path is available for smooth
changeover by the pantograph.

21. 14-Neutral Section
• Conventional 41 meters overlap neutral sections
are normally used.
• In suburban and heavily graded sections, short
neutral section is used.
• On main line PTFE neutral section should be
used in place of short neutral section.
• Neutral section should be located at sufficient
distance from the stop signal. 400 m after & 200
m before the stop signal in case of PTFE).

22. 15- Cantilever arrangement
• Swiveling type bracket assembly is used on
OHE.
16- Setting Distance of Masts
• Normal setting distance for BG is 2.8/2.5m. It
can be reduced to 2.36 m only in special
circumstances with the approval of CEE.
• Setting distance of masts on platforms should
not be less than 4.75m .

23. Maintenance problems with OHE
• Availability power & traffic block.
• Movement of Tower wagon.
• Availability of spares.
• Availability of experienced staff.
During foot patrolling following should
be observed
• Any abnormality wear and tear to be observed.
• Any other abnormal/ unusual situation .

24. 17- Seasonal and Cyclic checks
Pre-monsoon checks-
• Condition of insulators /Tree cutting & trimming
Pre-summer checks-
• Free movement & Y- value of ATDs.
• Re-tensioning of wire.
Pre winter Checks:
• Free movement of ATDs & checking of Z/X/Y
value of ATDs & checking of heaters in cubicles.
• Checking of T/out and X-over

25. Maintenance Schedules
• Foot patrolling
• Current collection tests
• Special checks.
• Annual maintenance and tower wagon
checking
• Periodic overhaul
• Cleaning of Insulator

26. Bonding & Earthing
Bonds
• Structure bond / Continuity bonds / Z-Bonds /
Cross Bonds
Earthing
• Stabilize circuit potential
• Protect men and material from injury
• Provide low impedance path to fault current
• Earth value should be
TSS =0.5 Ω, SP / SSP=2.0 Ω & AT=10 Ω

27. BreakDowns
Types of OHE breakdowns-
• Uprooting or damage to OHE masts / Portals
due to cyclone / derailments etc.
• Entanglement of pantograph with OHE.
• Snapping of OHE conductors.
• Flashover or other damage to insulators.
• Faults on account of stray wires etc.
• Theft.

28. • Any abnormality / damage to OHE should be
immediately reported to the TPC by the crew/
staff who notices it.
• If TPC can not be contact, nearest station /
cabin should be informed, who in turn will inform
to TPC with full details.
• TPC shall, on receipt of the information
(i)Switch off supply to affected section ,
(ii) Inform the section controller,

29. (iii) Send OHE staff to obtain full details of
damage.
(iv) Take decision to allow the traffic with panto
down based on available details.
(v) Send staff for attending the breakdown.
• The staff reaching at site will protect the broken
OHE.
• A quick assessment of damages.
• Immediate Rush to breakdown site.

30. • Assessment of assistance required from other
departments.
• DRM should be kept informed continuously
about restoration work and expected restoration
time.
• The officers / Supervisors at the site should keep
continuous touch with TPC.
• Evidences related to breakdown especially in
case of a panto entanglement, should be
preserved.

31. Power factor correction
• Power factor of an equipment defined as useful
power (kW)/ apparent power (kVA).
• Low power factor is indication of inefficient
system & cost high electricity charges.
• Stiff penalty for low pf by CERC/SERC.
• Methods of improving power factor :
Provision of fixed capacitor bank.
Provision of dynamic reactive power compensator.

32. Fixed Capacitor Bank
• Use of series or shunt capacitor with load.
• Advantages of shunt capacitor :
Current of supply side reduced resulting in lower
losses & voltage drop.
Improved Power factor on supply side.
Improved Receiving end volt & line regulation
kVA loading of all equipment bet. Cap. & supply
source is reduced.

33. • Advantages of series capacitor :
Can be located in general at any where in system
Voltage Improvement is precise & spontaneous with
widely fluctuating load.
More system stability and increased power
transference limit.
Dynamic reactive power compensator
• Used where wide fluctuation & prolonged period
of light load.
• Precise control power of power factor to the
desired level.

34. • Capacity of capacitor bank is divided in steps &
each step controlled by thyristors/IGBT.
• Switching action take place during voltage zero
across thyristor to obtain transient free
switching.
• A proper balance of static and dynamic voltage
support is needed to maintain voltage levels
within an acceptable range.

35. Important OHE Parameters

37. Foot by foot survey
• A field book is prepared based on foot by foot
survey.
• The details in the field book are dated and
progress in accordance with increasing
chainage.
• All the important features along the track and
their offset from the centre line of the track are
recorded.
• Track centers, width of cess, offsets of
continuous running drains, fences or pipes,

38. …cables are recorded at 50m intervals on M/L
and 25m interval in yards.
• Cross section of the route is recorded every
250 m.
• OHE structures , anchor foundations marked on
according to principles for OHE layout plans and
Sectioning Diagrams - Called pre-pegging plan.
• Verified at site and modified to suit field
conditions. Final plan is called pegging plan.
• Pegging plan forms basis for cost estimates and
schedule of quantities.

39. Reconnaissance Survey → Foot by foot
Survey → Field Book → Field Sketches →
Survey Plan → Pre-pegging plan → Pegging
plan → OHE layout plan.
Precautions during new wiring:
• Span should not be less the 27 meters and more
than 72 metes.
• Span of tramway type OHE should not be more
than 63 metes.
• Normal encumbrance of 1.4 m should be
adopted.

40. • Half tension length not more than 750 m.
• On curves, half tension length not more than 600
meters.
• Contact wire gradient should not be more than 3
mm / meter on main line and 10mm / meter on
sidings .
• Relative gradient of contact wire should not be
more than 0.5 mm/ meter on main line.
• A stagger of + 200 mm on straight line and not
more than 300 mm on curves.

41. • The two consecutive spans should not defer by
more than 18 meters.
• The Axial distance bet. Cat. and con. wire at
smallest dropper >150 mm. Normal contact wire
height 5.6 mm.
• Pre sag of 100/80 mm should be given to the
contact wire.
• Minimum contact wire height of 4.92 m over line
structures to permit movement of “C” Class
ODCs without physical lifting of wires.

42. • Contact wire height of 5.80m in electric loco
sheds and loco inspection pits.
• Erection tolerance of + 20mm is permitted.
• A provision of 275 mm ( max) for future track
raising.
• Neutral sections should be located away from
the stop signals.
• Section insulators should be provided within
within 1/10th to 1/3th of the span, from the
cantilever, in the direction of traffic.

43. • These should be avoided on main line. Droppers
should be provided as per droppering schedule.
• Crossing of equipment of different elementary
sections in the anchoring spans should be
avoided.
• Parallel span of not less than 2 meters should be
available for smooth changeover by the
pantograph.
• Insulated overlaps should be protected by stop
signals.

44. Final Checking:
• Jointly by divisional officers, construction /RE
officers and contractor’s representative.
• Compliance with latest drawings/ approved
plans.
• Cantilever assembly – adequate margins in
bracket stay and register tube for slewing.
Availability of check nuts, splits pins, tightness of
nuts etc.,
• Anchoring points – free movements of ATDs.
Correct X/Y values as per temp, proper
tensioning of antricreep wire.

45. Safety Checks:
• Availability of “Electric Shock Treatment Chart”
in the Dy.SS Office, IOW, PWI, CSI Offices,
• OHE depots, PSI depot , TSS & Switching
stations.
• Public & staff caution boards for high voltage
lines to be available at station entrances, PF
pillars etc.

46. • Availability of 25 kV caution boards on FOBs &
ROBs.
• Availability of danger boards on level crossing
height gauges.
• Engine stop boards at the end terminations of
the OHE.
• “Caution unwired turnout” boards ahead of all
unwired turnouts.
• Warning boards for neutral sections.

47. • Boards for “switching on “ and “switching off” of
power at neutral sections.
• Danger boards near watering stations.
• “25kV Caution boards” at substations and
switching stations
• Caution notices on all Electric, Diesel & Steams
locomotives.
• Caution boards at such signal posts where
protective screens can not be provided.

48. Safety Certificates:
• Certificate regarding OHE.
• Certificate regarding bonding & earthing.
• Certificate regarding safety instructions and
precautionary measures.
• Certificate by DRM regarding safety
precautions.

49. Important OHE Parameters
Normal height of contact wire at
support point for regulated OHE
5.60m ( pre.
Sag of 100
mm)
Normal height of contact wire at
support point for unregulated OHE
5.75m (temp.
range 40C to
650C)
Minimum height of contact wire at
support point for unregulated OHE
5.60m (temp.
range 150C
to 650C)

50. Minimum height of contact wire at
loco inspection pit
5.80m.
Minimum height of contact wire at
level crossing
5.50m.
Height of the “height gauge” at level
crossing
4.67m
Dia of new contact wire 12.24mm
Condemned dia of contact wire on
main line
8.25mm
Condemned dia of contact wire on
loop lines/ yard lines
8.00mm

51. Stagger of contact wire on tangent
track
+ 200mm
Stagger of contact wire at curved track + 300mm
Stagger of catenary wire on tangent
track at support for single cantilever
0
Gap between two parallel running
contact wires at un-insulated overlap
200 mm
Gap between parallel running contact
wire at insulated overlap
500mm
Height of contact wire of turnout OHE
above contact wire of the main line
OHE
5 cm

52. Height of contact wire of turnout OHE
above contact wire of the main line
OHE
5 cm
Track separation at turnout and cross
over at the location of obligatory
structure
150-
700mm
Minimum implantation at obligatory
structure/ mast supporting more than
one OHE
3 m
Normal implantation ( standard) 2.50m
+ 0.03mm
Minimum implantation ( critical ) with
CEE approval
2.36m

53. Minimum implantation ( critical ) with
CEE approval
2.36m
Minimum implantation on platform 4.75m.
Normal encumbrance 1.4 m. for
72 m
span
Maximum permissible slope of contact
wire on main line
1mm/mtr.
Maximum permissible slope of contact
wire in yards
3mm./mtr.
Short time min. vertical electrical
clearance
200mm.

54. Minimum implantation ( critical ) with
CEE approval
2.36m
Minimum implantation on platform 4.75m.
Normal encumbrance 1.4 m. for
72 m
span
Maximum permissible slope of contact
wire on main line
1mm/mtr.
Maximum permissible slope of contact
wire in yards
3mm./mtr.
Short time min. vertical electrical
clearance
200mm.