Traction distribution

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
•7/5mmcopperwire
•Inclineddropper–toholdregistertubewith
brackettube-7mmdia.
•Firstdroppersfromcantileverat4.5meters.Dia-
5mm.

4. Jumpers:
•Custrandedwireof160/105/50Sq.mm
•Carrycurrent/equalizepotential
“G”Jumper(105Sq.mm)annealedcopper
wire-InUn-isulatedO/L.
“C”Jumper(50Sq.mm)strandedcopperwire
–Todistributecurrentbet.Con.&Cat.wire
“F”Jumper(50Sq.mm)strandedcopperwire
–ProvidedoneithersideofisulatedO/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 uprightsand3legspecialBFBportalscan
alsobeusedinexceptionalcaseswhere
trackseparationisless.

7. Foundations:
Side
bearing
Used in good consolidated hard soil,
Bearing prr. > 10000 kgf/sq.m
Side gravityUsed where shoulder width is not
sufficient
Pure gravityUsed 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
•41metersinlengths.
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 overlap200 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. SurveyBeforeElectrification
Techno-EconomicSurvey:
•AssessthefeasibilityofElectrificationona
particularroute.
•Availabilityofpowersupply.
•Suitabilityoftheterrainandoftheoverline
structures.
•Availabilityofterminal/yardsforchangeof
traction.
•Costoftheproject.
•Financialviabilityoftheinvestmentbasedon
discountedcashflowmethod.

12. •Footbyfootsurvey
•ReconnaissanceSurvey
•Precautionsduringnewwiring
•FinalChecking
•SafetyChecks
•SafetyCertificates

13. Energizing New Line
•Clearancecertificatefromthecontractor
regardingallmenandmaterialsremoved.
•JointCertificatebySr.DEE’sofREandopenline
thatallstaffhasbeenremovedandwarned.
•CertificatefromS&Tofficersthattheirworkhas
beencompletedandOHEcanbecharged.
•SanctionofEIGforenergisationistaken.
•SanctionofCRSisobtained.
•CertificateofclearanceofDOT.

14. •Afterallformalities,thenewlineischargedin
presenceofaseniorelectricalofficerinfollowing
sequencestepbystep
25kVfeedersfromsubstationtofeedingpost.
Busbarsofthefeedingposts.
Firstsub-sector.
Secondsubsectorandsoon
Confirmatorytestsforproperoperationof
protectiverelaysshouldbecarriedout.

15. Principles of preparation of Layout
Plan
1-ElectricalClearance–Ashorttimeclearance
of200mm&workingclearanceof2m.
2-Windpressure–Consideredfordesignof
mastsanddeterminationofspans.
3-Span-Between27metersto72metesinsteps
of4.5masperrequirement.
4-Masts,Portals,Headsspansandfoundations
-ShouldbeselectedaccordingtoEmployment
schedule

16. 5-Contact wire height –
Standardcontactwireheightof5.6meters.
Nearoverlinestructuresminimum4.92M.In
locosheds5.8M.
Atlevelcrossingsnotlessthan5.5M.
6-Stagger–+200mmismaintainedon
straightlineandupto300mmoncurves.
7-Encumbrance–1.4misadopted.Near
overlinestructuresreducedupto0.3M.
8-Droppers-Asperdropperingschedulefor
agivenspanandencumbrance.

17. 9-SectionInsulators-Axialdistancebetween
thecatenaryandcontactwireatsection
Insulatorlocationshouldnotbelessthan600
mm(450mmincaseofsinglewiresection
insulators)
•Staggerofthesectioninsulatorshouldnormally
bezero.Innocaseitshouldexceed+100mm.
•SectionInsulatorshouldbelocatedwhere
distancebetweencentrelineoftwotracksis
morethan1.65m.Iffreeendoftherunnersis
awayfromcentreofturn0ut,itcanbereduced
to1.45m.

18. 10-Jumpers-DifferenttypesofJumperstobe
providedasdiscussedearlier.
11-Tensionlength
•Thehalftensionlengthshouldbemorethan750
meters.Oncurves,itshouldbereducedto
600M.
•Terminationofanti-creepanchoravoidedinside
thetunnelsonbridgemasts.
•UnregulatedOHE,tensionlengthofupto2000
meterscanbeadoptedonmainlinesaswellas
curves.

19. 12-AnchorRestriction–
•CrossingofOHEofdifferentelementary
sectionsintheanchoringspan.
•Crossingofregulatedandunregulated
equipments.
•Vicinityofsignals,watercolumns.
•BacktobackanchoringoftwoOHEonthesame
mast.

20. 13-Location of overlap-
•OverlapsshouldbesolocatedthatATDdoes
notcomeonplatform.
•Insulatedoverlapsshouldbeprotectedbystop
single.
•Feedingoverlapsshouldbesufficientlyaway
fromthestopsignal.
•Spanoftheoverlapshouldbesuchthatatleast
2meterparallelpathisavailableforsmooth
changeoverbythepantograph.

21. 14-Neutral Section
•Conventional41metersoverlapneutralsections
arenormallyused.
•Insuburbanandheavilygradedsections,short
neutralsectionisused.
•OnmainlinePTFEneutralsectionshouldbe
usedinplaceofshortneutralsection.
•Neutralsectionshouldbelocatedatsufficient
distancefromthestopsignal.400mafter&200
mbeforethestopsignalincaseofPTFE).

22. 15-Cantilever arrangement
•Swiveling type bracket assembly is used on
OHE.
16-SettingDistanceofMasts
•NormalsettingdistanceforBGis2.8/2.5m.It
canbereducedto2.36monlyinspecial
circumstanceswiththeapprovalofCEE.
•Settingdistanceofmastsonplatformsshould
notbelessthan4.75m.

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
•Anyabnormalitywearandteartobeobserved.
•Anyotherabnormal/unusualsituation.

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
•Currentcollectiontests
•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
•Earthvalueshouldbe
TSS=0.5Ω,SP/SSP=2.0Ω&AT=10Ω

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. •Anyabnormality/damagetoOHEshouldbe
immediatelyreportedtotheTPCbythecrew/
staffwhonoticesit.
•IfTPCcannotbecontact,neareststation/
cabinshouldbeinformed,whointurnwillinform
toTPCwithfulldetails.
•TPCshall,onreceiptoftheinformation
(i)Switchoffsupplytoaffectedsection,
(ii)Informthesectioncontroller,

29. (iii)SendOHEstafftoobtainfulldetailsof
damage.
(iv)Takedecisiontoallowthetrafficwithpanto
downbasedonavailabledetails.
(v)Sendstaffforattendingthebreakdown.
•Thestaffreachingatsitewillprotectthebroken
OHE.
•Aquickassessmentofdamages.
•ImmediateRushtobreakdownsite.

30. •Assessmentofassistancerequiredfromother
departments.
•DRMshouldbekeptinformedcontinuously
aboutrestorationworkandexpectedrestoration
time.
•Theofficers/Supervisorsatthesiteshouldkeep
continuoustouchwithTPC.
•Evidencesrelatedtobreakdownespeciallyin
caseofapantoentanglement,shouldbe
preserved.

31. Power factor correction
•Powerfactorofanequipmentdefinedasuseful
power(kW)/apparentpower(kVA).
•Lowpowerfactorisindicationofinefficient
system&costhighelectricitycharges.
•StiffpenaltyforlowpfbyCERC/SERC.
•Methodsofimprovingpowerfactor:
Provisionoffixedcapacitorbank.
Provisionofdynamicreactivepowercompensator.

32. Fixed Capacitor Bank
•Useofseriesorshuntcapacitorwithload.
•Advantagesofshuntcapacitor:
Currentofsupplysidereducedresultinginlower
losses&voltagedrop.
ImprovedPowerfactoronsupplyside.
ImprovedReceivingendvolt&lineregulation
kVAloadingofallequipmentbet.Cap.&supply
sourceisreduced.

33. •Advantagesofseriescapacitor:
Canbelocatedingeneralatanywhereinsystem
VoltageImprovementisprecise&spontaneouswith
widelyfluctuatingload.
Moresystemstabilityandincreasedpower
transferencelimit.
Dynamic reactive power compensator
•Used where wide fluctuation & prolonged period
of light load.
•Precise control power of power factor to the
desired level.

34. •Capacityofcapacitorbankisdividedinsteps&
eachstepcontrolledbythyristors/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. Footbyfootsurvey
•Afieldbookispreparedbasedonfootbyfoot
survey.
•Thedetailsinthefieldbookaredatedand
progressinaccordancewithincreasing
chainage.
•Alltheimportantfeaturesalongthetrackand
theiroffsetfromthecentrelineofthetrackare
recorded.
•Trackcenters,widthofcess,offsetsof
continuousrunningdrains,fencesorpipes,

38. …cablesarerecordedat50mintervalsonM/L
and25mintervalinyards.
•Crosssectionoftherouteisrecordedevery
250m.
•OHEstructures,anchorfoundationsmarkedon
accordingtoprinciplesforOHElayoutplansand
SectioningDiagrams-Calledpre-peggingplan.
•Verifiedatsiteandmodifiedtosuitfield
conditions.Finalplaniscalledpeggingplan.
•Peggingplanformsbasisforcostestimatesand
scheduleofquantities.

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.
•Contactwiregradientshouldnotbemorethan3
mm/meteronmainlineand10mm/meteron
sidings.
•Relativegradientofcontactwireshouldnotbe
morethan0.5mm/meteronmainline.
•Astaggerof+200mmonstraightlineandnot
morethan300mmoncurves.

41. •Thetwoconsecutivespansshouldnotdeferby
morethan18meters.
•TheAxialdistancebet.Cat.andcon.wireat
smallestdropper>150mm.Normalcontactwire
height5.6mm.
•Presagof100/80mmshouldbegiventothe
contactwire.
•Minimumcontactwireheightof4.92moverline
structurestopermitmovementof“C”Class
ODCswithoutphysicalliftingofwires.

42. •Contactwireheightof5.80minelectricloco
shedsandlocoinspectionpits.
•Erectiontoleranceof+20mmispermitted.
•Aprovisionof275mm(max)forfuturetrack
raising.
•Neutralsectionsshouldbelocatedawayfrom
thestopsignals.
•Sectioninsulatorsshouldbeprovidedwithin
within1/10thto1/3thofthespan,fromthe
cantilever,inthedirectionoftraffic.

43. •Theseshouldbeavoidedonmainline.Droppers
shouldbeprovidedasperdropperingschedule.
•Crossingofequipmentofdifferentelementary
sectionsintheanchoringspansshouldbe
avoided.
•Parallelspanofnotlessthan2metersshouldbe
availableforsmoothchangeoverbythe
pantograph.
•Insulatedoverlapsshouldbeprotectedbystop
signals.

44. Final Checking:
•Jointlybydivisionalofficers,construction/RE
officersandcontractor’srepresentative.
•Compliancewithlatestdrawings/approved
plans.
•Cantileverassembly–adequatemarginsin
bracketstayandregistertubeforslewing.
Availabilityofchecknuts,splitspins,tightnessof
nutsetc.,
•Anchoringpoints–freemovementsofATDs.
CorrectX/Yvaluesaspertemp,proper
tensioningofantricreepwire.

45. SafetyChecks:
•Availabilityof“ElectricShockTreatmentChart”
intheDy.SSOffice,IOW,PWI,CSIOffices,
•OHEdepots,PSIdepot,TSS&Switching
stations.
•Public&staffcautionboardsforhighvoltage
linestobeavailableatstationentrances,PF
pillarsetc.

46. •Availabilityof25kVcautionboardsonFOBs&
ROBs.
•Availabilityofdangerboardsonlevelcrossing
heightgauges.
•Enginestopboardsattheendterminationsof
theOHE.
•“Cautionunwiredturnout”boardsaheadofall
unwiredturnouts.
•Warningboardsforneutralsections.

47. •Boardsfor“switchingon“and“switchingoff”of
poweratneutralsections.
•Dangerboardsnearwateringstations.
•“25kVCautionboards”atsubstationsand
switchingstations
•CautionnoticesonallElectric,Diesel&Steams
locomotives.
•Cautionboardsatsuchsignalpostswhere
protectivescreenscannotbeprovided.

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.