The common misunderstanding is that ionizing radiation and electromagnetic radiation are indistinguishable. To completely eliminate our misunderstanding of high-voltage lines, we must first understand these two concepts.
1. ionizing radiation
according to the different effects of radiation on substances, people divide radiation into ionizing radiation and non-ionizing radiation. Ionizing radiation refers to radiation that carries enough energy to make electrons in atoms or molecules of matter become free, thus ionizing these atoms or molecules.
humans mainly receive natural radiation from nature. It comes from the sun, cosmic rays and radionuclides in the earth's crust. Radon overflowing from underground is another important source of natural radiation. Cosmic rays from space include quantized photons, electrons, gamma rays and x-rays. The main radionuclides found in the earth's crust are uranium, thorium and polonium, and other radioactive substances. They emit alpha, beta or gamma rays.
And artificial radiation mainly comes from medical and industrial fields. Such as medical equipment (such as medical and imaging equipment); Research and teaching institutions; Nuclear reactors and their auxiliary facilities, such as uranium mines and nuclear fuel plants. Facilities such as the above will inevitably produce radioactive waste, some of which will leak a certain dose of radiation into the environment.
In the work of exposure to ionizing radiation, harmful effects can occur if the protective measures are improper, the operating rules are violated, and the radiation dose of human body exceeds a certain limit. Under the action of electric radiation, the reaction degree of the body depends on the type, dose, irradiation conditions and sensitivity of the body. Ionizing radiation can cause radiation sickness, which is a systemic reaction of the body. Almost all organs and systems have pathological changes, but the changes in nervous system, hematopoietic organs and digestive system are the most obvious. The damage caused by ionizing radiation can be divided into acute radiation injury and chronic radiation injury. Receiving a certain dose of radiation in a short time can cause acute damage to the body, which is usually seen in nuclear accidents and radiotherapy patients. However, scattered exposure to a certain dose for a long time can cause chronic radiation injury, such as skin injury, hematopoietic disorder, leukopenia and impaired fertility. In addition, excessive radiation can also cause cancer and cause fetal death and deformity.
2. electromagnetic radiation
electromagnetic radiation is the momentum and energy transmitted in the form of waves by electric and magnetic fields that oscillate in the same direction and are perpendicular to each other, and its propagation direction is perpendicular to the plane formed by the electric and magnetic fields. The interaction between electric field and magnetic field produces electromagnetic waves, which are emitted or propagated into the air to form electromagnetic radiation. Electromagnetic radiation has an oscillation of electric field and magnetic field components, which propagate energy in two mutually perpendicular directions.
according to frequency or wavelength, electromagnetic radiation is divided into different types, which include (increasing frequency in order): electric power, radio waves, microwaves, terahertz radiation, infrared radiation, visible light, ultraviolet rays, X-rays and gamma rays. Among them, the wavelength of radio waves is the longest and the wavelength of gamma rays is the shortest. X-ray and gamma-ray have strong ionization ability, while other electromagnetic radiation has relatively weak ionization ability, while those at lower frequencies have no ionization ability. Some electromagnetic radiation has certain influence on human body.
However, there is a necessary condition for electromagnetic radiation, that is, there must be a time-varying source, and the frequency of the time-varying source should be high enough to produce obvious radiation effects, generally above 3Hz.
the frequency of alternating current in our country is only 5Hz, which is far from it, so high-voltage lines and substations will not produce so-called electromagnetic radiation at all.
3. Since high-voltage lines will neither produce ionizing radiation nor electromagnetic radiation, where is the danger of high-voltage lines?
High-voltage lines will not produce radiation, but will produce extremely low-frequency electromagnetic fields, or induced electric fields and induced magnetic fields called power frequency electric fields and power frequency magnetic fields. In this electromagnetic field environment, the human body will produce induced current, which needs to be controlled.
4. how to control this induced current?
keep a safe distance. according to the test, the intensity of electromagnetic environment outside the safe distance of 22KV power facilities is not as high as that of household appliances, so you can rest assured. Moreover, in the design and construction of power facilities, including high-voltage lines, there are strict standards for safe distance. Generally, there will be signs at the safe distance to remind you not to approach, mainly because you don't kill yourself, and it is 1% safe.
5. what is the spark you usually hear and see on the high-voltage line? Is there any harm?
The sparks generated by high-voltage lines are called corona professionally. Corona discharge is a discharge phenomenon caused by the high electric field intensity on the surface of transmission lines, which causes air ionization. The free intensity of air molecules is generally 2 ~ 3 kV/cm. When the surface electric field intensity of high-voltage lines exceeds this value, you will hear the hissing sound of the lines, smell the smell of ozone, and see the blue-purple fluorescence around the wires at night, which is corona discharge.
the corona of the line will cause power loss, power frequency electromagnetic field (AC transmission), DC field effect (DC transmission), radio interference (high-frequency pulse current) and audible noise, but it will not produce high-frequency radiation and will not cause harm to human body. The only harm may be that the hissing noise affects your sleep, which is especially obvious in EHV and UHV lines and substations, but there are few people near EHV and UHV.