Busbars, as a rule, connect equipment at high-voltage switchyards, and low voltage devices in battery banks. Their use allows for a significant reduction in installation space, material consumption, and labor costs. In open installations, electrical substations, and high-power switchgears, busbars can operate outdoors without protective covers. Electrical bussing is made of copper, steel, or aluminum, in the form of strips, rods, extrusions of tubular, rectangular, or other sections. Busbars can be produced covered with a protective sheath.
Types of BusbarsThere are several different busbar designs, which differ depending on various design features, purpose, installation method, and other factors. Let's take a closer look at the main types of busbars. Based on the construction and designation of the bus bar, they are divided as follows.
- Single bus-bar systems - consist of few incoming and outgoing lines connected to the same single bus-bar.
- Double bus-bar systems - are the systems of duplicated low voltage and high voltage bus-bars.
- Ring bus-bar system - a system where two circuit breakers are located on the same line. It always has 2 parallel paths to the circuit which can save it from interruption.
Varieties and Design FeaturesOpen busbars are used for laying networks in normal conditions without an aggressive environment, whereas protected and coated busbars are the main types that are commonly used to carry out electrical distribution in production. Protected models are enclosed with a box made of metal sheets to protect against accidental penetration by objects, or against accidental touches of workers.
The smallest permissible installation height of protected busbars is at least 2.5 m above the floor. Closed devices are allowed to be installed at any height, which makes the installation easier. In this case, a busbar trunking can be mounted along the location of the machines at a height of up to 1 meter above the floor. This reduces the cost of branch cables for connecting power to the machine tools.
Busbar MaterialsThe material of electrical busbars must meet a number of requirements: to provide the necessary electrical conductivity, mechanical strength, be resistant to chemical influences of the environment, and have a low weight and cost. Copper, aluminum, and steel can be used as busbar materials. Copper busbars are used only in special cases due to high costs. Steel busbars can be used in low-power electrical installations with operating currents up to 200-300 A.
For economic reasons, as a rule, busbars are made of aluminum and its alloys with various electrical and mechanical characteristics.
Busbar Trunking SystemsBusbar trunking systems are devices designed for electric power distribution using copper or aluminum busbars. They consist of bare or insulated conductors, insulators, and structures that are used for the transmission and distribution of electricity in industrial premises, on the territories of industrial enterprises, etc.
Compared to conventional types of electrical wiring, busbars have high reliability of power supply, and they require less time and means during installation work. They make it possible to move electrical receivers around and safely disconnect and connect them without interrupting the power supply of other electrical receivers. In addition, they take up little space and require little maintenance. Busbars are most widely used in installations up to 1,000 V in the form of trunk lines or distribution lines. Along with this, in devices of 6, 10, 35 kV, cable and conventional bus lines are also replaced with complete busbars. They are installed at power plants, at large substations, at industrial enterprises, etc.
Design of Electrical Busbar SystemsBusbar trunking design depends on the busbar dimensions, their shape and arrangement, the type of insulators, and the way the busbars are protected from environmental influences. Electrical busbar systems can be open (bare busbars on support insulators) or closed, with an insulator. Complete closed bus ducts are most widely used in low voltage networks. Flat aluminum busbars are the most often used type. Bus bars of various series and types consist of separate sections of various configurations. Bus sections can be flat, angle-like, or other shapes.
Metals Bus Bars Are Made ofLike other wiring products, busbars are often made from copper or aluminum. The difference between these metals is well known to any electrician - copper is preferable in terms of its electrophysical characteristics but more expensive. Due to its availability, it is advisable to use aluminum for large volumes of purchase.
The conductivity of copper is more than one and a half times higher than that of aluminum. In other words, all other things being equal, you can use a copper bar with a smaller section than an aluminum one. Heat loss in the case of copper busbars will also be lower.
Copper is also more independent of environmental conditions. Despite the fact that aluminum can be used almost everywhere without fear of corrosion, copper gives it a significant head start in this regard. It is important that copper does not oxidize as much in the open air as aluminum; it does not form an oxide film that creates resistance. Aluminum is not as strong or flexible. Though, sometimes people choose to use aluminum as the material for electrical bussing.
Characteristics of Aluminum BusbarsA finished aluminum electrotechnical busbar is a rectangular profile with a smooth surface with rectangular sections. The thickness of an aluminum busbar should be 3-10 mm. In the production of such conductors from aluminum in the form of the main raw material.
In defense of aluminum, it should be said that it also has certain advantages inaccessible to copper. First, there is a more affordable price for aluminum of the same length, width, and thickness. Secondly, aluminum is much lighter than copper, which allows to reduce the load on structural elements.
The main characteristic properties of aluminum electrical current conductors are as follows:
- The low weight of the finished product;
- Lack of magnetic properties and toxicity;
- Long service life;
- Excellent anti-corrosion properties;
- Sufficient rates of electrical conductivity and thermal conductivity.