BUS BAR ARRANGEMENT For power system Design.ppt

Bus bar arrangement

1. BUSBAR
ARRANGEMENT
ErSatishKumar Patnaik
Deputy. Manager (El)
400/220/132 KV Grid Substation, Meramundali

2. CONTENT
1.INTRODUCTION TO POWER SYSTEM
2.SUBSTATION OVERVIEW
3.EQUIPMENTS IN SUBSTAION
4.SINGLE LINE DIAGRAM
5.SUBSTATION EQUIPMENT POSITIONING
6.BUS BAR ARRANGEMENT

3. INTRODUCTION TO POWER SYSTEM
•The power system is a network which consists generation, distribution and
transmission system.
•Generation, Transmission and Distribution are three major components of
power system.
•In electrical generating power stations, electrical power is generated at
medium voltage level that ranges from 11 kV to 25 kV
•In India Various Transmission Level Voltages available are : 765 KV, 400 KV,
220 KV & 132 KV (3 Phase 3 Wire System)
•33 KV and 66KV Voltage levels are used in Sub Transmission system (3 Phase 3
Wire System).
•11 KV Voltage Level is used for Primary Distribution System (3 Phase 3 Wire)
•400 V 3 Phase 4 wire system is used for secondary distribution system.

7. SUBSTATION OVERVIEW
Asubstationis a part of an electricalgeneration,transmission,
anddistributionsystem.
Substation transformsvoltagefrom high to low, or the reverse, or
perform any of several other important functions.
Between the generating station and consumer, electric power may
flow through several substations at different voltage levels.
A substation may includetransformersto change voltage levels
between high transmission voltages and lower distribution voltages,
or at the interconnection of two different transmission voltages.
A switching station is a substation without transformers and
operating only at a single voltage level.
Substation can be Air Insulated Type (AIS) , Gas Insulated Type (GIS)
or Hybrid Type.

8. EQUIPMENT IN SUBSTATION
The substaion/switchyard generally comprises of following
equipments.
1.Bus bars
2.Circuit Breakers
3.Disconnectors& Earth Switches
4.Current Transformers
5.Voltage Transformer
6.Wave Trap
7.Surge Arrestor
8.Power Transformers

9. BUS BAR
OuterBusbarshallbeStrain/FlexibleandRigidtype.
Theoverheadconductorsshallbestrain/flexibletype,whichare
strungbetweensupportingstructuresandstrain/tensiontype
insulators.
Thebundledconductorbusbarmaybeconsideredfor220KVand
Abovesystemtooptimizethesteelstructure.
Intherigidtype,pipesareusedforBusbarandalsoformaking
connectiontovariousequipments,whereverrequired.Thebusbars
andtheconnectionaresupportedonthepedestalmountedonPI.

12. CIRCUIT BREAKER
Acircuitbreakerisanelectricaldevicedesignedtoprotectanelectrical
circuitfromdamagecausedbyanovercurrentorshortcircuit.
Itsbasicfunctionistointerruptcurrentflowtoprotectequipmentandto
preventtheriskoffire.
Unlikeafuse,whichoperatesonceandthenmustbereplaced,acircuit
breakercanbereset(eithermanuallyorautomatically)toresumenormal
operation.
Thecircuitbreakermainlyconsistsoffixedcontactsandmovingcontacts.
Innormal“ON”conditionofthecircuitbreaker,thesetwocontactsare
physicallyconnectedtoeachotherduetoappliedmechanicalpressureon
themovingcontacts.Thereisanarrangementstoredpotentialenergyin
theoperatingmechanismofcircuitbreakerwhichisreleasedifthe
switchingsignalisgiventothebreaker.
BasedonoperatingmechanismCircuitbreakercanbeclassifiedas:
PneumaticType,HydraulicType,SpringOperatedtype.

13. The most general way of the classification of the circuit breaker is on the basis
of the medium ofarc extinction. Such types of circuit breakers are as follows :-
1.Bulk Oil Circuit Breaker
2.Minimum Oil Circuit Breaker
3.Air Blast Circuit Breaker
4.Sulphur Hexafluoride Circuit Breaker
5.Vacuum Circuit Breaker
6.Air Break Circuit Breaker.

14. Bulk Oil Circuit Breaker

15. Vacuum Circuit Breaker

16. Minimum Oil Circuit Breaker

17. SF6 CIRCUIT BREAKER ( GANG OPERATED)

18. SF6 CIRCUIT BREAKER (INDIVUALLY OPERATED)

19. ISOLATOR & EARTH SWITCH
Isolators are off load disconnectorswitches.
Should be operated in current zero condition.
Sometimes used in on load condtionduring
equipotentialoperation mode.
Earth switch are used to discharge trapped charges of
line.
Mechanical and electrical interlock should be present
between earthswitchand Isolator to avoid accident.

20. Double Break Isolator

21. Vertical Break Isolator

22. Pantograph Isolator

23. Centre Break Isolator

24. Earth Switch & Isolator Arrangement

25. CURRENT TRANSFORMERS
Acurrenttransformerisatypeoftransformerthatisusedtoreduce
currenttoadesiredvalue,sothatwecanuseitinmetersandrelaycircuit
safely.
Itproducescurrentinsecondarywhichisproportionaltoprimary.
SecondaryofCTshouldnotbekeptinopencircuitedduringcharged
condition.
UsuallystandardCToutput/secondarycurrentis1Aor5Ai.e.when
ratedcurrentflowsthroughCTprimaryitproduces1A/5Aatsecondaryside.
GenerallyCTConsistsofmultiplecorewhichisusedforprotectionand
meteringpurposes.
CTaremaybeLivetanktypeorDeadtanktype

26. Dead Tank CT

27. Live Tank CT

28. POTENTIAL TRANSFORMER
AlsocalledVoltageTransformer(VT).
Theseareparallelconnecteddevice.
VTcanbeoftwotypes:
1.InductiveVoltageTransformer(IVT)
2.CapacitiveVoltageTransformer(CVT)
Itisbasicallyusedtomeasurehighalternatingvoltageinpower
system.
Potentialtransformersarebasicallystepdowntrasformer.
PTSecondaryshouldneverbeshorted.
CVTcanalsobeusedforPLCCCommunicationpurposeapartfrom
measuringvoltage
UsualstandardsecondaryvoltageofPotentialTansformeris110V/√3
asitmeasuredphasevoltage.

29. Inductive Voltage Transformer

30. Capacitive Voltage Transformer

31. Wave Trap
Also known as Line trap.
It is a high frequency stopper (PLCC frequency-80 to 500 KHz) , parallel
resonant circuit which connected in series in power circuit.

32. SURGE ARRESTOR
A surge arrester is a device to protect electrical substation equipments
from over voltage/ lightening surges.
It is basically a non linear resistance device made up of Metal oxide
(Basically Zinc Oxide ) material, which offers high resistance during rated
voltage and very low resistance during High surge voltage.

33. Surge Arrestor

34. Power Transformer
A power transformer is a passive electromagnetic device that transfers
energy from one circuit to another circuit by means of mutual induction.
Parts of transfomerare as follows:
1.Main Tank
2.Bushing
3.Torret
4.ConsrvatorTank
5.Radiator
6.Core
7.Winding
9-Gas operated protection Device
10-Pressure relive Valve
11-Breather

37. SINGLE LINE DIAGRAM
Single line diagram (SLD) , also sometimes called one lines diagram, is a
simplest symbolic representation of an electric substation/ power system.
In 3 Ph System, the single line of SLD , represents all the three phases.

39. BUS BAR ARRANGEMENT
We have different types of bus -bar arrangements we need to choose
the required arrangement. This depends on various factors such as
I.System voltage.
II.Position of a substation in the system.
III.Reliability of supply.
IV.Flexibility.
V.cost.
VI.Availability of alternative arrangements if outage of any
of the apparatus happens.
VII.Bus -bar arrangement should be simple and easy to
maintain.
VIII.In case of load -growth there must be possibility to
extend the system to meet the load requirements.
IX.The installation should be as economical as possible,
keeping in view about the needs and continuity of
supply.

40. Types Of Bus -Bar Arrangements:
I.Single bus-bar arrangement.
II.Single bus-bar arrangement with bus sectionalized.
III.Double bus-bar arrangement.
IV.Double bus double breaker bus arrangement.
V.One main bus and one Transfer Bus arrangement
VI.Double main Bus one Transfer bus arrangement.
VII.One and half circuit breaker scheme.
VIII.Double bus system with bypass isolators.
IX.Ring bus arrangement.
X.Mesh Bus Arrangement

41. Single Bus Arrangement.
Thissinglebus-bararrangementconsistsofonlyonebus-barandallthe
incomingfeedersandoutgoingdistributorsareconnectedtothisbus-
baronly.

42. NORMAL OPERATING CONDITION

43. DURING FAULT

44. Advantages of single bus -bar arrangement:
1.It is easy in operation.
2.Initial cost is less.
3.Requires less maintenance.
Disadvantages of single bus -bar arrangement:
1.When a breakdown occurs then there will be whole
interruption of power supply.
2.Flexibility and immunity are very less.

45. SINGLE BUS BAR WITH BUS SECTIONISER
Insinglebus-bararrangementwithbussectionalizedwedivideasingle
bus-barintotwosectionswiththehelpofacircuitbreakerand
isolatorswitchesandloadisdistributedequallyamongbothsections.

46. DURING NORMAL OPERATING CONDITION

47. DURING FAULT

48. Advantagesofsectionalizedsinglebus-bararrangement:
1. As we are using circuit breaker to divide a bus -bar into two
sections, fault on one section will not interrupt power supply on the
other section & only few loads will have loss of power supply.
2. The fault level can be reduced by adding a current limiting
reactor.
Disadvantages of sectionalized single bus -bar arrangement:
1. We are using extra isolators and circuit breakers so that the
cost will be high.

49. Double Bus Bar Arrangement
BUS 1
BUS COUPLER
BUS 2

50. Double bus arrangement has two bus bars and the incoming feeders and
outgoing feeders are connected in parallel to both buses with the help of isolators..
We can divide the load among two buses with the help of isolator switches .
By closing the isolator switch that is connected to bus -bar 1 the load can be
connected to bus -bar 1 and by closing the isolator switch connected to bus -bar 2
the load gets connected to bus -bar 2.
Wehaveabuscouplerbreakerwhichisusedforbustransferoperation.When
weneedtotransferloadfromonebustootherbusinnormalsituation,weneed
toclosethebuscouplerfirstandthencloseisolatorsoftheassociatedbusto
whichloadistobeconnectedandopentheisolatorswitchcoupledtootherbus
andthenopenthebuscouplerbreaker.
However,infaultconditioninanyonebus,thebusswitchoveroperationcanbe
donewithoutclosingbuscouplerbreaker.Inthismethodfirstfaultybusisolator
willbeopenedandthenisolatorofhealthybuswillbeclosed(Atthistimebreaker
ofloadwillbeinoffconditiontoo)

51. Advantages of double bus system:
1. It has greater flexibility.
2. During fault conditions there is no long term interruption of power supply
to load.
Disadvantages of double bus system:
1. We cannot transfer load from one bus to other bus without interruption of
power supply for few minutes in case of bus fault.

52. DOUBLE BUS DOUBLE BREAKER BUS
ARRANGEMENT

53. Here we energize both the feeders and divide feeders among both the
buses but we can connect desired feeder to desired bus at any time.
For this purpose we need to close the isolator and then circuit breaker
associated with the required bus -bar and later open the circuit breaker
and then isolator from which is has to be disconnected.
NORMAL CONDITION

54. LOAD SHIFTING

55. FAULT ON BUS 1

56. FAULT ON BUS -2

57. ADVANTAGE
1.During fault conditions load can be transferred to one bus so there will not
be interruption in power supply.
2.In case of maintenance of any breaker , other breaker can supply the
whole load , hence no interruption required.
3.Here we are not using a bus coupler so there will not be much delay in
power supply while closing circuit breaker to transfer load from one bus to
other bus.
4.High flexibility.
Disadvantages
1. The number of circuit breakers used are high so cost is very high.
2. Maintenance cost will also be high.
So this type of arrangement is used very rare.

58. ONE MAIN BUS AND TRANSFER BUS SCHEME

59. In main and transfer bus arrangement we have two buses one is main bus
and the other is transfer bus. With the help of isolator switches it is
connected to the transfer bus which are called bypass isolators and with the
help of circuit breakers and isolator switches it is connected to the main bus.
In normal conditions the feeders are fed through main bus but during fault
conditions load is transferred to the transfer bus.
DURING NORMAL OPERATION

60. FEEDER ON TRANSFER BUS

61. FAULT IN MAIN BUS

62. Advantages of main bus and transfer bus system:
1. The main advantage is shifting the load from one type to another type if any
fault occurs loss of continuity..
2. Relays can be operated by using the bus potential.
3. The cost of repair and maintenance is less.
4-It is very easy to issue sectional shutdown by shifting the load to transfer bus
.
Disadvantages of main bus and transfer bus system:
1.Two bus -bars are used which increases the cost.
2.The whole system may breakdown if any fault occurs in any of the sections
on the bus.

63. TWO MAIN BUS ONE TRANSFER BUS
SCHEME

64. Load can be connected from any one bus at a time.
Bus change over possible when bus coupler is in on condition.
When required , by transferring the feeder to TBC, sectional shutdown
can be issued without interrupting power supply to that feeder.
ADVANTAGE
1.Load can be connected any bus at any time without interrupting
the power supply to that feeder.
2.By using transfer bus sectional shutdown of feeder can be given
without interrupting power supply.
DISADVANTAGE
1.Cost is more as 3 bus bars are used.

65. One and Half Breaker scheme
Herethetwofeedersarefedthroughtheircorrespondingbus-bars
andthesetwofeedersarecoupledbyathirdcircuitbreakercalledtie–
breaker.
Duringnormalconditionsallthethreecircuitbreakersareclosedand
thebothcircuitsoperateinparallelandpowerisfedtofeedersfromthe
twobus-bars.
Iffaultoccursononebusbarthenwiththehelpofsecondbus-bar
feedercircuitbreakerandtiebreakerpowerisfedtofeeders.Thismeans
eachfeederbreakerhastoberatedtofeedbothfeederswhichare
coupledbytiebreaker.
.

67. NORMAL OPERATION

68. MAIN BREAKER OPEN

69. TIE BREAKER OPEN

70. FAULT IN BUS

71. ADVANTAGE:
1.Therewillbenointerruptionofpowerincaseoffaultbecauseallthe
feederscanbetransferredtootherhealthybusimmediately.
2.Additionalcircuitscanbeeasilyaddedtothesystem.
3.Costislesscomparedtodoublebusdoublebreakerarrangement.
Disadvantagesofoneandahalfbreakersystem:
1.Thisarrangementiscomplicatedbecauseduringfaulttwocircuitbreakers
aretobeopened.
2.Maintenancecostishigh

72. DOUBLE BUS SYSTEM WITH BY PASS
ISOLATOR
This is combination of the double bus system and main and transfer bus
system.
In Double Bus System with Bypass Isolators either bus can act as main bus
and second bus as transfer bus.
It permits breaker maintenance without interruption of power which is not
possible in double bus system but it provides all the advantages of double bus
system. It is also uses only 2 buses hence it is economical as compared to 2
Main bus and transfer bus scheme.
It however requires one additional isolator (bypass isolator) for each feeder
circuit and introduces slight complication in system layout. Still this scheme is
best for optimum economy of system and it is best optimum choice for 220 KV
system.

74. ADVANTAGE:
1. No interruption of power supply because in case of fault load can be shifted to
transfer bus.
2. Load can be divided into two groups since they can be feed from either of the
buses
DISADVANTAGE
1. cost is high as we are using two bus bars and extra isolator switches.
2. Complex in nature
3-Complete loss of load during bus fault.

75. RING BUS ARRANGEMENT
Ring Bus arrangement provides double feed to each feeder circuit. Here the
end of the bus bars is returned upon themselves to form a ring. Hence it is
called main ring arrangement.
Here if one circuit beaker is damaged it is opened and the feeder can be
supplied from the other circuit breaker which is near to it.

76. NORMAL OPERATION

77. ONE BUS SECTION MAINTENANCE

78. FAULT IN ANY ONE SECTION

79. ADVANTAGE
1. Since each feeder is fed from two circuit breakers even if fault occurs in
one system the feeder can be fed from other system so there will be no
interruption of power supply under fault conditions.
2.The effect of fault is localized to that section alone and the rest of the
section continues to operate normally
DISADVANTAGE
1. There will be difficulty to add any new circuit in the ring.
2. Over loading problems may occur.

80. MESH BUS ARRANGEMENT
In mesh arrangement between the mesh formed by bus bars circuit
breakers are installed as shown in the following figure:

81. From the node point of mesh circuit is tapped.
We need to open two circuit breakers when the fault occurs so that protection
can be obtained but switching is not possible.
NORMAL OPERATION

82. FAULT IN ANY ONE SECTION

83. Advantages :
1. Provides protection against fault.
2. For substations having large number of circuits this arrangement is
suitable.
Disadvantages :
1. It doesn't provide switching facility.
2. Not suitable for all type of substations.