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4 Different Types of Busbar Schemes in power substations│Electronicsinfos

Various Bus bar Arrangement


Types of Busbar Schemes 2023


Many types of bus bar schemes are used in power substations.

Types OF Busbar Connection

  • Single Bus Bar Scheme
  • Single Bus Bar With Sectionalizer Scheme
  • Double Bus Bar Scheme
  • Ring Bus Bar Scheme

Single Bus Bar Scheme

A single bus bar is a main conductor or a set of conductors that carries the entire electrical load of the substation.

Components of Single Bus Bar Scheme

  1. Bus Bar
  2. Circuit Breakers
  3. Isolators
  4. Earthing Switch

In normal operation, all incoming and outgoing circuits are connected to the single bus bar, allowing the flow of electrical power through the system. During the maintenance mode of a particular circuit, isolators are used to disconnect the faulty circuit from the bus bar. The earthing switch is often employed to ground the isolated portion for safety.


single bus bar scheme
single bus bar

Advantages of Single Bus bar

  • we need a single circuit breaker in the feeder of the single bus bar Scheme
  • The single bus bar is a low-cost system
  • The relay system is simple in a single bus bar system.
  • In a single bus bar system, we do not need transfer break switches to break the connection.
  • The maintenance cost is low due to the minimum circuit breaker
  • Single bus bar allows the system that we used bus bar potentials to as relay.
  • The protective relay system is simple
  • The operating system is simple and its cost is low
  • single bus bar scheme used in 11kv
  • this scheme needs minimum space
  • fault tracking is easy in a single bus bar system

Disadvantages of single bus bar

  • For maintenance work in the single bus bar system, we need the whole system shutdown.
  • If we need to extend the system we also need to shut down the supply
  • The overall efficiency of the system is not good in a single bus bar.
  • The single bus bar scheme is non-reliable.
  • A single bus bar scheme is not used for more than 33kv.

Single Bus Bar With Sectionalizer Scheme

if we divide the single bus bar system into two parts and use one brake and two isolators in each system. we also divide the single bus bar system into multiple systems. how many we need bus bar sections depends on the importance of substations and switching requirements.

Single Bus Bar With Sectionalizer Scheme
bus bar with sectionalize

we know that in a single bus bar system if we need maintenance work we need to shut down the whole system which results in the consumers being affected in this process. To overcome this problem we divide the single bus system into two or multiple parts as per requirements.

Sectionalized bus bar scheme uses different circuit breakers and isolators in each system. the control system and supply system of each bus bar system are different. when any fault occurs or we need to do maintenance work we just shut down a particular bus bar system. this is easy for consumers. when we shut down the particular supply we shut down the circuit breaker and then open the isolators because we always operate isolators with no load.

when we restore the supply we first close the isolators and then on the circuit breaker In this scheme we also use current limiting reactors to minimize the fault MVA to reduce the circuit breaker capacity sectionalized bus bar we use different AC sources that's why both parts must be synchronised. the meaning of synchronizing is that the frequency, phase sequence and voltages must be the same in both parts of the bus bar system.

Advantages of Sectionlize Single Scheme

A sectionalized single bus bar scheme is a type of power distribution system that provides several advantages over other schemes. Here are some of the advantages of a sectionalized single-bus bar scheme
  1. Improved Reliability
  2. Reduced Maintenance
  3. Flexibility
  4. Cost-effective
  5. Enhanced safety

Improved Reliability

The sectionalized single bus bar scheme increases the reliability of the power distribution system by reducing the impact of faults or failures in a particular section. In the event of a fault or failure, only the affected section needs to be shut down, while the rest of the system continues to operate normally.

Reduced Maintenance

The sectionalized single bus bar scheme reduces maintenance requirements by allowing sections of the system to be taken offline for maintenance without affecting the rest of the system.

Flexibility

The sectionalized single bus bar scheme provides greater flexibility in the operation of the power distribution system. It allows for the addition or removal of sections as needed, without requiring a complete overhaul of the system.

Cost-effective

The sectionalized single bus bar scheme is cost-effective compared to other schemes, as it requires less equipment and maintenance costs. 

Enhanced safety

The sectionalized single bus bar scheme improves safety by reducing the likelihood of accidents, such as electrical shocks and short circuits.

Disadvantages of Sectionlize Single Scheme

  • The initial cost of this Sectionlize bus bar Scheme is high.
  • Sectionlize bus bar scheme required more maintenance.
  • The number of breakers and isolators required
  • Sectionlize busbar system is complex as compared to a single busbar system
  • if a fault occurs in a particular section we must shut down the particular section for maintenance work.

Double Bus Bar Scheme

Two main conductors or sets of conductors are used each functioning as a main bus bar. The switching arrangement allows the system to be operated with either bus bar active.

During normal operation, one of the bus bars (Bus A or Bus B) carries the entire electrical load. The other bus bar remains idle, providing backup.

When maintenance or repair is required on one of the bus bars, the load can be transferred to the idle bus bar by using circuit breakers and isolators. This allows maintenance on the active bus bar without interrupting the power supply.

Double bus bar schemes are commonly used in critical power systems where reliability and availability are paramount, such as in substations serving hospitals, data centres, or industrial facilities. The Double Bus Bar Scheme is a reliable and flexible configuration for power substations, used without interrupting the power supply. 

double bus bar system
Double bus bar scheme

The cost of a double bus is high as compared to the single bus bar.

Advantages of Double Bus bar

  • in this scheme, we shift the complete load on each bus bar
  • high stability
  • maintenance is easy
  • used in extra high voltages
  • this scheme provides continuity of supply
  • protected and stable scheme
  • the consumer is not affected
  • efficiency is high as compared to a single bus bar system

Disadvantages of Double Bus bar

  • the initial cost of a double bus bar is high
  • this scheme is complex as compared to the single bus bar scheme
  • that needs more space as compared to the single bus bar.
  • the chances of a short circuit are available.

Ring Bus Bar Scheme

The ring bus bar scheme, also known as the meshing scheme, represents a specific configuration used in electrical power substations and switchyards. In this arrangement, circuit breakers and bus bars are connected in series, forming a ring-like structure. This scheme is recognized for its stability, and its operation ensures continuous power supply in normal conditions while allowing for fault isolation during abnormal situations.

ring bus
ring bus scheme

Advantages of Ring Bus Bar Scheme

  • maintenance and supervision are easy
  • the operating system is easy
  • the cost of maintenance is low
  • this scheme is used in most populated areas

Disadvantages

  • this scheme is limited to up to 6 circuits
  • the relay system is complex
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