Why does the high-voltage line buzz on a rainy day?

2020-11-25 14:32:31 浙江立洲线缆股份有限公司 Viewd 204

Many people think that the buzzing of high-voltage lines on rainy days is caused by leakage of high-voltage lines. No, No, No! If it rains and the electricity leaks, is it okay? !

In fact, this kind of sound is the ionization of the air near the power line, forming the noise produced by corona discharge. Because the air is humid in rainy weather, the resistance is low compared to dry weather, the high-voltage line discharges to the surrounding air, there will be a belching sound, but it will not form an arc or sparks.

So, when you hear the buzzing sound next to the high-voltage line, don't doubt that it is discharging. However, it only occurs in places where some wires have burrs or connected to electric poles, and they will not penetrate the air and have no effect on people or objects.

It's not only when it rains that there is sound

The high-voltage wire ionizes the air to form a discharge, making a belching sound. This phenomenon does not only occur on rainy days. Where does the sound come from? It’s not that the wires can speak, it’s actually like this--

In normal times, the alternating current on the high-voltage line will produce an alternating magnetic field. Under the action of the magnetic field, the wire will vibrate and make sound. The frequency of sound is closely related to the frequency of alternating current. In fine weather, the sound will be smaller and it will be easily covered by the background noise of the surrounding environment. When it rains, as the air humidity increases, the air resistance decreases and the corona discharge increases, which will cause the discharge sound to increase.

Theoretically, wet weather will worsen the insulation, and the safe distance between people and high-voltage lines needs to be larger than usual. But don't worry, when the power supply company is setting up the line, it has left enough safety distance. Normally, there is no danger for people passing under the wires.

Of course, Toutiao recommends that everyone try not to stand under high-voltage power lines for a long time in rainy days.

Is it dangerous to answer the phone under high-voltage lines?

We said: Such worries are completely unnecessary!

As for the power of electromagnetic waves in mobile phones, it is not worth mentioning. In general, the higher the electromagnetic wave frequency, the stronger the ionization effect. The frequency of mobile phone radio waves is too low to ionize air at all.

Therefore, making calls under high-voltage lines will not increase the probability of being charged. If the mobile phone explodes, it is mostly due to the quality of the battery itself, and the high-voltage line is innocent.

>>>High Voltage Line

Electricity is inseparable from our daily life. It is inseparable from mobile phone chargers to urban construction. Electricity is transmitted through a "grid" composed of power plants, high-voltage lines, substations and low-voltage lines. The most common "power grid" is the high-voltage line, that is, the wires on the "iron tower".

According to GB/T 2900.50-2008, definition 2.1, high voltage usually does not contain 1000V. High-voltage lines usually refer to transmission lines that carry voltages above 10KV (including 10KV).

>>>Sometimes what is going on with the "biao" sound heard under the high-voltage transmission tower?

During high-voltage power transmission, a strong electric field is formed around the wire, which ionizes the air and forms a corona discharge. This discharge can be heard and seen. The higher the voltage level, the stronger the corona of the wire and the greater the noise.

It is not easy to observe corona discharge on the 10 kV and 35 kV distribution lines in the urban area, because most of the distribution lines use insulated wires, which will not produce air ionization, and the voltage level is low, the corona intensity is weak, and it is easy to Covered by the background brightness and noise of the environment. At night or in rainy and foggy weather, a faint blue-violet halo can sometimes be observed near 220 kV, 500 kV high-voltage transmission lines.

2. How far is it safe to keep a distance from high-voltage lines?

>>>How far is the distance between people and high-voltage lines to be safe?

Under normal circumstances, the human body safety voltage is 36 volts. If the voltage level exceeds this voltage level, people may be electrocuted. Not to mention the 110kV high voltage line! Take fishing electric shock as an example. Nowadays fishing rods are generally made of carbon materials, which have strong electrical conductivity, and the fishing line will also conduct electricity when it gets wet. Don't believe in any insulation tape. High voltage is like a small river dam to block a flood, and it is simply vulnerable.

Of course, many people mistakenly believe that as long as they do not touch the high-voltage line, there will be no electric shock. The actual situation is that when high-voltage lines and high-voltage live equipment are in normal operation, the voltage they carry is often several thousand volts, tens of thousands of volts or even hundreds of thousands of volts. When the human body and objects are close to them, these high voltages may penetrate the air between them and the human body and objects, and discharge through the human body. When the current passes through the human body, it will cause electric burns and even death. This is the so-called high voltage. Electric arc. Of course, the greater the air distance, the less likely it is to be broken down, and enough air distance can achieve insulation.

>>>The high-voltage line is safe from residential areas?

Considering from the perspective of power safety, and considering that high-voltage lines are caused by high winds to cause wind deviation, according to Article 5 of the Implementation Rules for the Protection of Electric Power Facilities: “Overhead power line protection areas are to ensure the safe operation and protection of built overhead power lines A safe area that must be set up for normal power supply for people’s lives. In densely populated areas such as factories, mines, towns, market towns, and villages, the overhead power line protection area is the horizontal distance of the conductor edge after the maximum calculated wind deviation and the level of the building behind the wind deviation. The area within the two parallel lines formed by the sum of the safety distances. The horizontal safety distances from the buildings to the building under the condition of calculating the maximum wind deflection of the voltage conductors at all levels are as follows:

The safe distances that must be maintained for high-voltage live lines of different voltage levels. When objects enter these safe distances, they will cause discharge. According to the "Implementation Rules for the Protection of Electric Power Facilities", the safe distance for high-voltage lines below 1 kV is 4 meters; the safe distance for 1-10 kV high-voltage lines is 5 meters; the safe distance for 35-110 kV high-voltage lines is 10 meters; the safe distance of the 154-220 kV high-voltage line is 15 meters.