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TOPIC-: Various Bus Bar Arrangement

Submitted by -:Sharukh khanBranch -: electricalUID -: k11652Semester-: 5th /3rd year

Submitted to-:Mr. kamal AroraHOD of Electrical department

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CONTENTS CONDUCTOR USED FOR BUSES

SINGLE BUS WITH BUS SECTIONALISER SINGLE BUS SYSTEM

DOUBLE BUS SYSTEMDOUBLE BREAKER BUS SYSTEMONE AND A HALF BREAKER BUS SYSTEMMAIN AND TRANSFER BUS SYSTEM

DOUBLE BUS SYSTEM WITH BYPASS ISOLATORRING BUS SYSTEM

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CONDUCTOR USED FOR BUSESAll Aluminum conductor (AAC)

All Aluminum alloy conductor (AAAC) Aluminum conductor with aluminum alloy reinforced (ACAR) Aluminum conductor with steel reinforced (ACSR)

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SINGLE BUS SYSTEM

Advantages-:1.Simple in Design2.Less Expenditure

Disadvantages-:1.In case of bus fault or bus bar isolator fault or maintenance total Substation is out of service.2.In case of maintenance of transformer circuit breaker the associated transformer has also to be shut-down. Similarly for Line also.

In this arrangement, the single bus-bar is divided into sections and load is equally distributed on all the sections. Any two sections of the bus bar are connected by a circuit breaker and isolators.

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SINGLE BUS WITH BUS SECTIONALISER

Advantages:1. One complete section can be taken out for Maintenance without disturbing the continuity of other section. 2. If a fault occurs on one section of the Bus, that faulty section alone will be isolated.Disadvantages:

It will be a little more costly with the addition of one isolator and some cases with Circuit breaker, C.Ts and C&R panel.

Some advantages are realized if a single bus bar is sectionalized with circuit breaker. If there are more than one incoming and the incoming sources and outgoing feeders are evenly distributed on the sections as shown in the figure, interruption of system can be reduced to a good extent.

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DOUBLE BUS SYSTEM

Advantages: Double Bus Bar Arrangement increases the flexibility of system.

Disadvantages::The arrangement does not permit breaker maintenance with out interruption

In double bus bar system two identical bus bars are used in such a way that any outgoing or incoming feeder can be taken from any of the bus.

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DOUBLE BREAKER BUS SYSTEMAdvantages:There is no need of bus coupler as because the operation is done by breakers instead of isolator

Disadvantages:Most expensive as it involves additional breaker, CT Isolators etc for each circuit.

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ONE AND A HALF BREAKER BUS SYSTEM

Advantages:During any fault on any one of the buses, that faulty bus will be cleared instantly without interrupting any feeders in the system since all feeders will continue to feed from other healthy bus.

Disadvantages:This scheme is much expensive due to investment for third breaker.

This is an improvement on the double breaker scheme to effect saving in the number of circuit breakers. For every two circuits only one spare breaker is provided. The protection is however complicated since it must associate the central breaker with the feeder whose own breaker is taken out for maintenance.

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MAIN AND TRANSFER BUS SYSTEMSwitching operation-:

1. First close the isolators at both side of the bus coupler breaker.2. Then close the bypass isolator of the feeder which is to be transferred to transfer bus.3. Now energized the transfer bus by closing the bus coupler circuit breaker from remote4. After bus coupler breaker is closed, now the power from main bus flows to the feeder line through its main breaker as well as bus coupler breaker viatransfer bus.5. Now if main breaker of the feeder is switched off, total power flow will instantaneously shift to the bus coupler breaker and hence this breaker will serve the purpose of protection for the feeder.6. At last the operating personnel open the isolators at both sides of the main circuit breaker to make it isolated from rest of the live system.

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DOUBLE BUS SYSTEM WITH BYPASS ISOLATOR

Advantages: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.

Disadvantages:It however requires one additional isolator (bypass isolator) for each feeder circuit and introduces slight complication in system layout.

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.

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RING BUS SYSTEMAdvantages:It provides a double feed to each feeder circuit, opening one breaker under maintenance or otherwise does not affect supply to any feeder. But this system has two major disadvantages.

1. Flexibility for breaker maintenance2. Each breaker removable without disconnecting

load3. Only one breaker needed per branch,4. Each branch connected to network by two

breakers5. All change-over switching done with circuit-

breakers & hence flexible.

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