The bus is a low-resistance conductor . The term "bus" does not apply to the geometric shape, dimensions or dimensions of the conductor [1] . In low voltage electrical installations, buses are used to connect several separate electrical circuits . In high-voltage installations, as a rule, high-voltage devices are connected to each other by busbars in those places where a low active and reactive resistance is required; this can significantly reduce the installation area, material consumption and labor. In open installations - electrical substations and high-voltage switchgears - buses can be operated outdoors without protective covers. Rigid tires are made of copper, steel or aluminum, in the form of plates (strips), rods and profiles of tubular, rectangular or other section. The flexible busbar may be a copper metal plate (or a set of plates) or a cable product of twisted conductors. Tires can be produced bare or in a protective sheath.
Busbar
A busbar trunking is a device made of uninsulated or insulated conductors, insulators and structures that are used to transmit and distribute electric power in industrial premises, on the territories of industrial enterprises, etc. Compared to conventional types of electrical wiring, busbar trunkings have high reliability of power supply and less time and means during installation works, they make it possible to move electric receivers in the workshop to any place and safely disconnect and reconnect them without having to break in the power supply of other power consumers. In addition, they take up little space and do not require special care. Busbars are most widely used in installations up to 1,000 V in the form of complete trunk or distribution lines. Along with this, in 6, 10, 35 kV devices, cable and ordinary bus lines also began to be replaced by complete busbars. They are installed at power plants (in the generator-transformer block), at large substations (as bus lines), at industrial enterprises (for power-consuming installations), etc.
The design of the busbar depends on the size of the tires, their shape and relative position, type of insulators and the method of protecting tires from environmental influences. Busbars can be open (non-insulated busbars on support insulators) or closed, with an insulating or metal casing. Complete closed busbars are most widely used in low voltage networks. In busbars, flat aluminum tires are most often used. Busbars of various series and types are equipped with separate sections of various configurations. Sections can be straight, angular, branch and other forms. The complete busbar trunking, in addition to sections, may include: junction boxes containing protective equipment for the branches; transition nodes for interconnecting busbars of various types and other structural elements.
By purpose, busbars are divided into trunk, distribution, lighting and trolley.
Trunk busbars
Trunk lines are busbars intended for the construction of trunk lines, communication of substations on the low-voltage side, to power distribution busbars, distribution points, individual large power receivers with voltage up to 1,000 V at a frequency of 50 Hz. Busbars are a complete electrical network, consisting of structures for mounting and individual sections, interconnected in the prescribed manner. They are made in separate sections of normalized length - straight and curly (angular and branch), which allows you to assemble a busbar of any configuration.
Different end flanges are mounted depending on the LVRN of the stress reliever.
Busbar Distribution
Distribution busbars are busbars with lower rated currents (usually 250, 400, 630 A) and a large number of branches. Serve for direct connection to them of power consumers.
To prevent accidental mechanical damage, distribution busbars are laid at a height of 2.5 - 3 m from the floor, using the following mounting options:
- direct mounting to the ceiling;
- hanging from the ceiling or trusses with the help of rigid suspensions;
- direct mounting to the wall or columns of the building;
- resting on supports fixed to the floor
Lighting Busbars
used to connect lighting devices or consumers of low power and released on currents from 25 to 40 A.
Trolley Busbars
they are used to power workshop electric receivers of rolling stock (for example, cranes, crane beams, monorails, floor trolleys, fabric cutting units) and are produced for currents from 35 A to 1 kA.
Advantages of busbars. The main advantages of busbars are:
· Ease of installation;
· Flexibility in operation - unlike cable, bus systems can be easily changed, supplemented or transferred to another room, building and reinstalled without special capital costs;
· Compact design, ease of inspection and high operational reliability;
· Busbars are less combustible compared to conventional power cables.
The disadvantages of busbars include their higher cost compared to cables. However, if we compare the whole design of the power supply system using busbars and cable lines, taking into account the installation and operating costs, the use of busbars looks economically justified.
A conductive device consisting of busbars mounted on supports made of insulating material in channels, ducts or similar sheaths, and equipped with installation and connecting fittings, is called a busbar trunking . Busbars can be arranged at the installation site from disparate elements or assembled from modular sections of factory-made busbars.
Busbar may consist of the following elements:
- straight sections with or without branch nodes;
- sections for changing the position of the phases, branching, rotation, as well as input and transitional;
- branch sections.
Inside the control cabinet: bus with layering protected by fuse links. Above right is the main circuit breaker.
Power frequency current busbar and fuses connected to it in the cabinet. Tire colors meet USSR standards.
Industrial frequency current busbar and circuit breakers connected to it in the cabinet. The color markings of tires comply with USSR standards.
Busbar current industrial frequency in the cabinet. Wiring to complete fuses has been completed. The entry and tires are protected against contact by insulating pads.
Power frequency current busbar and main circuit breaker (electronic release) connected to it in the cabinet.
Combined (common) protective earth bus in the cabinet.
Double pole bus for connecting devices on a DIN rail
Busbars for current 1500 A (input into a large building)
- 110 kV
Notes
- ↑ GOST R 51321.1-2007. Devices complete low-voltage distribution and control. Part 1: DEVICES TESTED COMPLETELY OR PARTIALLY. General technical requirements and test methods.