Causes of overhead power line breaks

Date: January 4, 2011 |
Category: Articles, Electrical installation work Tags: , Laying cables in the ground This material was prepared by specialists.
Do you need electrical installation or electrical measurements? Call us! The New Year's news feeds in our country are more and more reminiscent of the script of a new film - a disaster. Hundreds of large settlements are cut off from electricity, tens of thousands of people celebrate the holidays in sheepskin coats by candlelight. Airports are unable to receive and dispatch planes, holding crowds of passengers hostage. Heat guns are used to heat people. They have enormous thermal power and can heat not only unheated or poorly heated rooms, but also outdoor areas. The use of heat guns is widespread on farms and households, on construction sites and retail areas. What types of heat guns are there? Diesel locomotives are appearing on railways instead of the usual electric trains. The reason for all these troubles is the same - the weather is abnormal for the central regions. Freezing rain, heavy snowfall, low temperatures.

As a result of such weather disasters, an ice crust (ice) forms on the wires of overhead power lines. The thicker this crust of ice, the heavier the wire becomes. When the thickness of the ice reaches a critical level, insulators shatter into pieces, wires break, and overhead power line supports fall.

We should not forget that overhead power lines pass not only through open areas, but also through forests. Tree trunks and branches, under the weight of snow and ice, fall onto the wires, which inevitably leads to breaks, short circuits and fires. This is what we have been seeing everywhere lately.

Is it all Mother Nature's fault? And why do we always refer to abnormal weather phenomena? Chubais has not been at the helm of the energy complex for a long time, and emergency situations occur with enviable regularity all the time.

Most power outages could be avoided if power companies periodically carried out work to clear overhead power lines of trees, cut clearings and monitor the condition of poles, insulators and wires, especially since these electrical installation works are included in the cost of electricity.

Do not forget that when designing power lines, preference is given to overhead lines, since it is believed that it is much cheaper. But power engineers are cunning, because overhead power lines require large costs for their maintenance and restoration after the next abnormal weather event, although from an economic point of view it would be more rational to lay cable lines in the ground instead of overhead lines.

A cable power line consists of one or more cables laid in the ground or in special cable structures - boxes, tunnels, overpasses. Modern technologies make it possible to use cables for all voltage classes. Laying cables in the ground is possible in cities, towns, and on the territories of industrial enterprises. Now, as a rule, cable lines are used where it is not possible to build overhead lines. Cable lines have undeniable advantages over overhead power lines. The main disadvantage of overhead power lines is that they are subject to many vagaries of nature. Cable lines laid in the ground do not depend on natural phenomena. Unless there is a global earthquake with a shift in the earth's crust or an unknown volcano erupts.

Overhead power lines require a specific space called a containment zone. It is prohibited to build any structures or carry out any type of work in this zone. It’s no secret what level land prices have now reached, so renting land for a line or buying it into ownership will require very large costs.

Underground power lines are not visible from the surface of the earth, therefore, unlike overhead lines, they will not spoil the appearance of city landscapes. It is also preferable to lay cables in densely built areas and where construction is planned in the future. When using cables, losses at high loads are significantly reduced, which will supply consumers with higher quality electricity. And saving energy resources is currently considered the main direction in energy policy.

Currently, in most large cities of our country, projects for the long-term development of underground cable laying are being implemented, which provide for an increase in the length of cable lines. In the near future, it is planned to remove most of the overhead power lines into the ground, that is, to dismantle the overhead lines and lay new cable lines in the ground. After all, the use of these technologies will make it possible to most effectively plan urban development and develop energy systems in modern megacities.

Other and useful information

Automation systems and devices in 6-10 kV networks

Overhead lines are made for the most part using steel-aluminum and aluminum wires, supports made of reinforced concrete or wood. Today, the following automation systems and devices are used in 6-10 kV networks:

restart devices;
devices for switching on backup power;
sectioning devices;
control and signaling devices.

Power lines are connected in an extensive network through an automatic transfer point. When the network load is from 10 to 100 kVA, pole-type substations are used, which are installed on a support. For loads from 160 kVA, closed or kiosk substations are most often used. In 6-10 kV electrical networks, the installation of external vacuum switches and fuses-disconnectors is provided.

Rice. 2. Closed transformer substation

What to do if you fall

The first thing to do if you notice a tree falling on an electrical wire line is to call the emergency service and notify its specialists of the situation.
Then it is necessary to photograph or video record the tree after it falls on the wires, and in the presence of several witnesses, also document everything in writing. It is also necessary to notify law enforcement authorities.

This is necessary in a situation where there is a threat of causing moral damage. In this case, a special check may be required to ensure the absence of illegal actions regarding the property of the victim (if any).

If, as a result of a falling tree, electrical wires were damaged, which resulted in large-scale material damage, a special inspection can be ordered to assess the condition of the fallen tree, the damage caused as a result of its fall, and also to identify the culprit. The results of this check can become key evidence if you suddenly have to resolve the issue in court.

To speed up the elimination of the consequences of a falling tree, you can also involve a management company, which, in addition to the emergency service, can also be contacted.

It should also be remembered that if there is a break in the wires, it is strictly prohibited to be near them, especially in wet weather. Otherwise, you may suffer from electric shock.

Finding the exact location

Having identified the approximate location where the broken wire is located, they begin a thorough search. You can find the exact location of the breakdown in different ways.

Opening walls during renovation

Opening up old electrical wiring is the best way to check it.
The simplest and most effective way to check the condition of wiring and eliminate tears is to completely clean the walls of finishing materials. Only in this case can you familiarize yourself in detail with the condition of the grooves, which were made specifically for hidden wiring. They differ from other surfaces in color, and several layers of putty are additionally applied to them.

This method is advisable only during a major overhaul, accompanied by the complete dismantling of all decorative coatings.

Logical search methods

Switching wiring lines are usually located above the sockets.
If the owner of the living space does not have a diagram of the electrical network, it can be recreated using logical methods. You should familiarize yourself with the basic principles of laying electrical communications:

Most often, wiring is carried out at intervals of 10-15 cm from the ceiling or floor (the first option is more common).
Installation of electrical communications is carried out strictly along vertical and horizontal grooves. Errors are possible, but small.
Communication lines that are located above switches and sockets are always laid straight up. In these areas, hammering nails and using drills and hammer drills is prohibited.

Based on the location of switches and sockets in an apartment or house, you can recreate the electrical communications circuit with high accuracy.

Malfunctions in control systems of automated systems

Automated telecontrol and telesignaling tools provide the ability to monitor the correct operation of installed restart devices, backup power switching devices, and automated sectioning devices. However, when introducing such functionality into the existing medium voltage overhead line infrastructure, certain problems arise. Let's highlight the main ones:

distortion of the received data due to the impact of adverse meteorological conditions;
the need to use special encoding and decoding equipment;
the need to invest significant funds in the process of introducing technology and operating such systems.

Rice. 3. Modernization of medium voltage overhead lines

Searching for electrical wiring for preventive purposes

It is recommended to draw up a detailed wiring diagram when purchasing a new home.
As practice shows, most often the residents of a house or apartment start looking for wires in the walls only when problems arise. However, for preventive purposes, you should also know the location of the highway.

When purchasing a new home, it is recommended to create a detailed wiring diagram so that its integrity is not damaged during repairs.
Draw up a plan before implementing the planned redevelopment. It is extremely important to take into account the location of electrical communications when any manipulations are made, even with interior walls.
When hanging accessories, sconces and pictures, it is also important to know where the conductive wires run, otherwise hammering nails will cause trouble.

To recreate the path of the electric route, it is recommended to use one of the methods of searching for break points, or ask for a diagram from the previous owners, if it has been preserved.

The procedure for determining a broken wiring in the wall

Multifunctional hidden wiring detector
Finding the location of the damage, regardless of the cause of the problem, is carried out in the following order:

First of all, you need to de-energize the wiring. To do this, turn off the automatic switch (switch).
Sometimes it is necessary to reduce the resistance level of the insulating layer of the wiring; to do this, it is burned through.
To search for a damaged area, they resort to induction or acoustic methods; you also need to arm yourself with an ordinary household multimeter and a transistor receiver.
To make searching easier, electricians also use locators. These devices, which have different modifications, allow you to accurately determine the path along which the cable is laid, find all current-carrying conductors, and also find out whether they are energized or not. Some models use them together with generators to increase efficiency.

Innovative electrical networks equipped with lines of beacon markers have been invented. This installation method is actively used in Europe and America. In Russia, this method has not yet become widespread. In this case, if the integrity of the wire is violated, the locator, based on a signal from the beacon, will quickly and with high accuracy determine the location of the break.