Electrical materials. Cables. Scheme, description

ENCYCLOPEDIA OF RADIO ELECTRONICS AND ELECTRICAL ENGINEERING
Free library / Electrician

Electrical materials. Cables. Encyclopedia of radio electronics and electrical engineering

Free technical library

Encyclopedia of radio electronics and electrical engineering / Electric installation work

By cable called one or more insulated and twisted cores, enclosed in an airtight sheath, over which various protective covers can be applied.

According to their purpose, cables are divided into power and control cables. Power cables designed for transmission and distribution of electrical energy to various pantographs and switchgear, control - for connection to electrical appliances, devices and clamp assemblies (in control, signaling and automation networks). According to the type of insulation and sheath, cables are divided into the following groups:

1) with impregnated paper insulation in a metal sheath;

2) with paper insulation impregnated with a non-flowing composition, in a metal sheath;

3) with plastic insulation in a plastic or metal sheath;

4) with rubber insulation in a plastic, rubber or metal sheath. In each group, cables are subdivided according to rated voltage, cross section, number and material of cores and type of protective cover.

Cables are manufactured in accordance with the current state (GOST) and industry standards (OST) and technical specifications (TU) for a rated voltage of 0,66; 1; 3; 6; 10; 20 and 35 kV and sections of conductive wires 1; 1,5; 2,5; 4; 6; 10; 16; 25; 35; 50; 70; 95; 120; 150; 185; 240; 300; 400; 500; 625; 800 and 1000 mm2. (110 kV high voltage cables will be discussed below.)

The conductors of the cables are made of copper wire grades MM (soft) and MT (hard) and aluminum grades AM (soft), APT (semi-hard), AT (hard) and ATP (high hardness). The wires are twisted into a strand (part of a flexible multi-wire core twisted from several wires) or into a core. With proper twisting, the wire in the core, in the strand, as well as the strands in the core, should be adjacent to each other, while there should be no crossing of wires or strands located in one layer. Depending on the flexibility, the cable cores are divided into six classes. For fixed laying of cables, conductors of classes I, II and III are used, for movable - more flexible conductors - IV, V and VI classes.

For stationary laying power cables, conductors are made in round, shaped or combined shapes.

The use of sector and segment cores instead of round ones makes it possible to reduce the cable diameter by 20-25% and, accordingly, reduce the consumption of other materials (for insulation, sheath and protective covers).

Depending on the conditions of cable laying, apply aluminum or copper conductors.

Copper single-wire conductors are made round for sections 1-50 mm and shaped for sections 25-50 mm; stranded conductors - round for sections 16-1000 mm2 and shaped for sections 25-300 mm.

Aluminum single-wire conductors are made round for sections 22 2,5-240 mm, shaped for sections 25-240 mm, stranded conductors - round for sections 70-1000 mm2, shaped for sections 70-240 mm2.

The use of single-wire aluminum conductors with a cross section of up to 240 mm reduces the cost of cables (twisting of individual wires is excluded), but increases their overall rigidity, which creates certain difficulties during installation.

In the designation of cables with single-wire cores, after the number indicating the cross section, the letters "ozh" are added.

For the manufacture of conductive wires, aluminum is mainly used. The resistance of an aluminum wire with the same cross section is 1,65 times greater than that of copper, therefore, to transmit the same power over a cable at the same voltage, the cross section of a conductive aluminum conductor should be taken more than copper. In addition, aluminum conductors have a lower yield strength and a higher heat capacity than copper.

Author: Bannikov E.A.

See other articles Section Electric installation work.

Read and write useful comments on this article.

<< Back

Latest news of science and technology, new electronics:

Solidification of bulk substances 30.04.2024

There are quite a few mysteries in the world of science, and one of them is the strange behavior of bulk materials. They may behave like a solid but suddenly turn into a flowing liquid. This phenomenon has attracted the attention of many researchers, and we may finally be getting closer to solving this mystery. Imagine sand in an hourglass. It usually flows freely, but in some cases its particles begin to get stuck, turning from a liquid to a solid. This transition has important implications for many areas, from drug production to construction. Researchers from the USA have attempted to describe this phenomenon and come closer to understanding it. In the study, the scientists conducted simulations in the laboratory using data from bags of polystyrene beads. They found that the vibrations within these sets had specific frequencies, meaning that only certain types of vibrations could travel through the material. Received ... >>

Implanted brain stimulator 30.04.2024

In recent years, scientific research in the field of neurotechnology has made enormous progress, opening new horizons for the treatment of various psychiatric and neurological disorders. One of the significant achievements was the creation of the smallest implanted brain stimulator, presented by a laboratory at Rice University. Called Digitally Programmable Over-brain Therapeutic (DOT), this innovative device promises to revolutionize treatments by providing more autonomy and accessibility to patients. The implant, developed in collaboration with Motif Neurotech and clinicians, introduces an innovative approach to brain stimulation. It is powered through an external transmitter using magnetoelectric power transfer, eliminating the need for wires and large batteries typical of existing technologies. This makes the procedure less invasive and provides more opportunities to improve patients' quality of life. In addition to its use in treatment, resist ... >>

The perception of time depends on what one is looking at 29.04.2024

Research in the field of the psychology of time continues to surprise us with its results. Recent discoveries by scientists from George Mason University (USA) turned out to be quite remarkable: they discovered that what we look at can greatly influence our sense of time. During the experiment, 52 participants took a series of tests, estimating the duration of viewing various images. The results were surprising: the size and detail of the images had a significant impact on the perception of time. Larger, less cluttered scenes created the illusion of time slowing down, while smaller, busier images gave the feeling of time speeding up. Researchers suggest that visual clutter or detail overload can make it difficult to perceive the world around us, which in turn can lead to faster perception of time. Thus, it was shown that our perception of time is closely related to what we look at. Larger and smaller ... >>

Random news from the Archive

Photon nose for monitoring crops 08.08.2022

Experts from two British universities are embarking on a new project to develop a photonic 'nose' to monitor crops for pests and plant diseases.

Aston University Birmingham is collaborating with Harper Adams University to research and develop technology to use light to monitor plant health. They will test the new technology on strawberries. After all, its berries are vulnerable to potato aphids, which can destroy the annual crop.

In general, with increasing pressure to find alternatives to pesticides due to environmental and human health concerns, one method is to use Integrated Pest Management (IPM) to establish an early warning system. The point is to constantly make sure that insects and diseases do not accumulate on the plants, instead of spraying the plants with chemicals. However, there are doubts about the cost and reliability of this method.

The new project uses the latest developments in photonic technology that can analyze the low levels of volatile organic compounds (VOCs) emitted by plants that are indicative of their health status. Thus, by connecting machine learning hardware, artificial intelligence can be put into practice in a commercial setting.

Monitoring technologies for invertebrate pests and plant diseases can significantly reduce crop losses.

However, most electronic noses use electrochemical sensors, which have issues with sensitivity, sensor drift, or aging effects, and lack specificity. We intend to solve this problem by building on the fast-moving technology of photonics - the science of light - and collaborating with scientists from other disciplines," said Professor David Webb of the Aston Institute of Photonic Technology (AIPT).

Other interesting news:

▪ Blue Origin Rocket

▪ Vector video codec developed

▪ LG Pocket Photo 2

▪ potato battery

▪ Weather and headache

News feed of science and technology, new electronics

Interesting materials of the Free Technical Library:

▪ site section Parameters, analogues, marking of radio components. Article selection

▪ article Retreat to prearranged positions. Popular expression

▪ article How do clouds manage to stay in the sky? Detailed answer

▪ article Acerola cherries. Legends, cultivation, methods of application

▪ article Rapid LED fire (option 2). Encyclopedia of radio electronics and electrical engineering

▪ article Radio station at 430 ... 440 MHz (on lamps). Encyclopedia of radio electronics and electrical engineering

Leave your comment on this article:

All languages of this page

Home page | Library | Articles | Website map | Site Reviews