Types of Busbars


Busbars are electrical conductors that run in a single strand or as tubular conductors. They vary in diameter and cross-section to provide different mechanical parameters. Busbars are non-isolated, and connectors are made from copper-aluminum alloy or bronze. Copper-aluminum busbars shall use bi-metallic connectors to prevent electrolytic corrosion. In addition, busbar enclosures are typically metallic.

Single Busbar

The main advantages of the single busbar arrangement are its flexibility and high reliability. Depending on the load of the transformer, the load can be transferred from one busbar to another without interruption. Moreover, de-energizing a single busbar section without interruption of supply does not reduce operation flexibility. It is also used in urban supply systems, especially those with high load density. Although the operational flexibility of a single busbar arrangement is not as high as that of a two-busbar configuration, it is a highly cost-effective solution when compared with the other options.

When considering the single busbar switchgear option, you must bear in mind that it is simpler to operate than its double-busbar counterpart. It also occupies less space, and the total cost of installation is cheaper. Single-busbar switchgear installations are typically composed of basic cubicles that are combined to form the required switchboard. 

Double Bus Double Breaker Arrangement

A double bus breaker arrangement is a circuit breaker that utilizes two separate busbars to distribute ac power. A double bus bar arrangement is also known as a sectionalized breaker arrangement. Another type of double bus breaker arrangement is called a ring or mesh arrangement. This arrangement has an advantage over other types of circuit breaker arrangements in that it requires fewer circuit breakers to operate. This type of breaker arrangement is useful in situations where there are many circuits to protect.

A double bus breaker arrangement has two separate buses for each circuit. Unlike a single-bus scheme, this arrangement allows maintenance of circuits without an outage. A faulty bus will not interrupt any circuits, because the remaining bus can feed it. However, double bus breaker arrangements require twice as much equipment as a single bus scheme. It is also highly reliable and offers load-balancing due to the additional circuit breakers. A double-bus breaker arrangement is most seen in EHV transmission substations.

Sectionalized Main Busbar

A busbar is an electrical junction that collects and distributes electrical energy. They are an essential component of electrical power distribution systems. They simplify the process of power distribution, lower costs, and improve flexibility. The various types of busbars are classified according to their construction and function. In a single busbar arrangement, there is only one busbar, and the feeders, transformers, and generators are connected to it via isolator switches. When one of these components fails, the entire system will be shut down. Similarly, in case of expansion, the main bus bar must be completely shut down.

Using isolators and circuit breakers in sectionalized main bus bar arrangements can protect the entire system from failure. This prevents a total substation shutdown when one section fails. These breakers can operate in either open or closed modes. A current limiting reactor will further limit the fault level. A current limiting reactor is another option to use in a sectionalized main bus bar system. The additional circuit breaker will prevent the entire substation from shutting down.

Mesh Busbar Arrangement

The mesh busbar arrangement resembles a mesh and is used when there are many interconnected circuits. This busbar arrangement has many advantages. For one, it has fewer circuit breakers and offers more security against bus-bar faults. It lacks the switching facility of the double busbar arrangement. Another advantage is that it is easy to install and maintain. But be aware that it does not have the switching facility of the single busbar arrangement.

The main difference between the two types of busbar arrangement is that the former is flexible, and the latter is not. The former is generally more expensive than the latter. This is because the mesh is essentially a single wire. It is used for larger projects that need a single power source and a flexible power distribution method. A busbar can house expandable track lighting and runs from a single power source. Among the common conductive metals used for busbars is copper, which is preferred because of its high-temperature resistance. This metal also offers an added sense of security during short circuit situations. On the other hand, aluminum is not conductive and can result in long-term reliability problems.

Ring Busbar

In the circuit ring-bus bar assembly, current enters the ring through various locations and travels around the circlips to the bus bar. The bus bar is generally larger than the circuit leads and is connected to the ring by a parallel circuit. In the figure, arrows indicate the general direction of the current flow. The ring and bus bar are typically connected with a stainless-steel shroud. Electrical insulation is placed between the ring and shroud to provide the necessary conductive shielding.

Another benefit of a ring bus bar arrangement is its ability to provide more flexibility and a redundant path to the circuit. This allows maintenance of circuit breakers without interrupting power. However, the disadvantage of this arrangement is that it's difficult to expand the ring bus bar system and add a new circuit line. Therefore, it is important to consider the requirements of the building and how it will operate.

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