Power supply wiring in the conditions of production enterprises and construction sites needs additional protection. Normal isolation does not always cope with these tasks, so special circuits are used that also perform distribution and optimized connection functions. A typical embodiment of such wiring is a busbar trunking containing one or more supply lines.
Device Overview
The busbar design is a rigid channel for laying cables operating under voltage up to 1 kV. The frequency of the alternating current in the network can be 50-60 Hz, and the power can be up to 250 A. The key characteristic is the resistance of the busbar trunking, since it is designed to protect the line from mechanical, thermal, humidity and chemical influences. IP classification is used to indicate protective properties. In particular, the trunking with IP68 marking can be used both in residential buildings and in substations and industrial workshops where extreme temperature loads are noted. Cast insulation also protects the circuit from pressure, water, dust and electromechanical interference. But in addition to the protective function, the busbar trunking also has an ergonomic task, which is to simplify the processes of connecting equipment to power grids.
Busbar classification
How different the conditions for the use of insulating casings can be, the types of busbars are just as varied. The most common classification features include the following:
- The degree of enclosure. There are both fully sealed and open structures. This directly depends on the communication requirements of the device and the operating environment.
- Mobility. Stationary and portable circuits are distinguished. The choice of the trunk busbar according to this criterion also depends on the nature of the cable application in specific conditions. Stationary buildings are more often used in enterprises with fixed fixed points and power supply channels. In turn, portable busbars are used at facilities with aggressive environments without a constant electrical infrastructure.
- The material of manufacture. Mostly used metal that has undergone processing to acquire anti-corrosion properties. These can be alloys of anodized aluminum (they are light and compact), and stainless steel (massive, but durable construction with a high degree of protection).
Types of busbar sections
An isolated channel of this kind does not at all belong to linear mines of the same type, which vary only in parameters of section and dimensions. A full-fledged busbar trunking has butt, rotary and other complex elements represented by sections of one type or another. The standard varieties of segments of the trunk busbar include the following:
- Connecting section. It is used for switching with the control panel and connecting the channel to the busbars of the electrical panel.
- End feeding section. It is introduced into the network to regulate the energy in the busbar by selecting it through a flexible cable.
- Corner connection section. It can be used to enter the bus into the network on complex turning areas, where it is impossible to use typical segments of the structure.
- Through segments. An extensive group of precast bus elements that are used in transitional and nodal technological areas with special requirements. For example, it can be passages through ceilings and walls, areas with increased fire hazard, etc.
Busbar trunking designs
A distinctive feature of such devices is the ability to withstand large currents in the range from 1600 to 4000 A. The standard configuration of the shaft allows you to install two supply couplers for every 6 m of the trunk. The most popular design execution format is the type of ShMA. This device contains three tires, one of which is represented by a zero contour removed from the case in the form of two aluminum corners. The basis of the SHMA trunk busbar consists of straight sections with a length of 75 to 350 cm. As additional functional segments, tee, corner, branch and a wide group of connecting elements can act. Flexible sections are used to avoid obstacles, which also allow changing phase rotation.
Busbar distribution structures
The main share of such devices is carried out according to the ballast control system with a current rating of up to 630 A. The primary task of the distribution routes is the functional network layout of the contours and branches of cable lines. Therefore, the current strength is low, but it provides extensive wiring layout options. Both distribution and trunk busbars provide for the integration of several points for the input of energy supply sources. But if the maximum number of the main canal rarely exceeds three, then the ballast control system allows you to connect up to six power consumers in the three-meter section. Four-bus distribution structures are also used, in which one zero and three phase circuits are provided.
Lighting Busbars
A special channel for creating a powerful and functional lighting system. In its arrangement, 25 A buses are used, and the phasing can be different - both at 380 and 220 V. Single-phase systems are also used in industrial conditions, when there is no need for a high load for low-cost consumers. It is possible to make a branch from the 0.4 kV busbar trunking along the SCO line, and then group the point junctions on single-phase plug connections for each lighting device after 5-10 m. The devices are suspended by means of clamps with hooks and connected to the plug. The mounting step of the structure on average varies from 2 to 3 m.
Busbar installation
The channel is installed using metal profiles and a fixing hardware system. Initially, a wiring diagram is drawn up indicating the gasket contours and busbar installation points. Next, the premises are prepared where the route will take place. In particular, cuts and holes are formed on the walls and floor, through which fastening will be carried out. Standard installation instructions for busbar trunking require that installation be carried out in conditions of readiness of the building for construction and repair operations with full protection of the channel elements from pollution and mechanical damage.
At the first stage, pads of U-shaped metal profiles are mounted. They are attached to the floor with screws, screws or dowels. Further, the body of the product is integrated into the existing groove, followed by a closing U-shaped profile that is joined to the bearing similar elements by means of an anchor bolt and a connecting pin.
Device application
As a protective and mounting electrical fittings, busbar trunking can be used not only at manufacturing enterprises in assembly shops with conveyor lines, but also in administrative, public and residential buildings. The wide range of applications of such devices is due to the high reliability and degree of protection, which allows you to protect the cable line from various kinds of damage. Power installation of the main busbar trunking can be carried out in almost any planning conditions - including through windows, openings and ceilings. This nuance also contributes to the distribution of accessories, complemented by sections of different sizes and formats.
Conclusion
When choosing a suitable busbar trunking, it is important to take into account not only the requirements for protecting the main conductive line, but also the logistic factors of the installation. The fact is that cable routes serve to power specific consumers, however, the position of the latter during the operation of the facility may vary. So that such rearrangements do not force to re-equip the electrical infrastructure, the configuration of the main busbar trunking is calculated in advance from the point of view of its interaction with the equipment being serviced. Of course, do not forget the risks of possible emergencies. They are laid at the stage of creating the project - for example, a typical busbar trunking must withstand an overload of up to 10% above the rated performance of the network for 2 hours / day. Microclimatic factors of influence, electromagnetic interference, etc. are calculated separately.