Traditional Culture Encyclopedia - Weather inquiry - Yichang stationed troops, and his home is less than 80 meters away from the 7.5 million kV high-voltage line. He works around all the year round. Is it harmful? What should I do?
Yichang stationed troops, and his home is less than 80 meters away from the 7.5 million kV high-voltage line. He works around all the year round. Is it harmful? What should I do?
There are two impacts of high-voltage lines on the surrounding environment: 1. Electromagnetic radiation or electric field; 2. Sound waves generated by mechanical vibration.
1. Electromagnetic radiation or electric field
We divide this high-voltage signal similar to pink noise into four intervals according to the radiation frequency band: >; 12GHz, 30MHz~ 12GHz, 150KHz~30MHz,<150khz.
Because this high-voltage signal is similar to pink noise, it is difficult to detect the high-voltage signal at >: the signal intensity above 12GHz is very weak, and this ultrashort wave will be much lower than the natural radiation level through a series of barriers such as walls, so it can be considered that the high-voltage line is harmless in this frequency band.
From 30 MHz to 12 GHz, the overall radiation trend of this frequency band to the same place decreases with the increase of frequency, but the radiation level may be greatly enhanced due to the higher harmonics generated at a high-intensity fundamental wave. If higher harmonics appear at a certain multiple frequency of 50Hz, the radiation at this frequency will become very high. Full-wave antenna must be used to measure in the field, and the radiation at a certain point can be measured by scanning from 30MHz to 12GHz. If you don't use a full-wave antenna to test, it is impossible to know the real radiation level. Because the test equipment is expensive and the test is complicated, it is difficult to have such a test.
150KHz~30MHz, because the wavelength of this frequency band is too long, it is almost impossible to get an antenna of this size because of the relationship between size and wavelength, so the radiation level of this frequency band is difficult to measure, but it can be calculated theoretically, but it can be analyzed by electric field when the distance from the high-voltage line is lower than the wavelength. If it is in the electric field of high-voltage line, it is necessary to calculate or test the electric field strength according to the distance.
& lt 150kHz, because the wavelength is very large, if the distance from the high-voltage line is longer than the wavelength, because the distance is too far, there is no need to evaluate the hazard of the high-voltage line at all, and the short distance is basically analyzed by electric field.
On the harm of electromagnetism and electric field.
Long-term exposure to high electromagnetic radiation will damage the nervous system, circulatory system and reproductive system to varying degrees. Long-term exposure to low electromagnetic radiation will destroy the magnetic balance of human body, which may lead to fatigue, mental decline, memory decline and shortened life. Electronic equipment in complex electromagnetic environment will greatly reduce the reliability, safety and life of electronic equipment.
Similarly, if the human body is exposed to a strong electric field for a long time, it may also lead to ion imbalance and cause various diseases. Electronic equipment in strong electric field environment will also reduce reliability, safety and life. If you open an umbrella near a high-voltage line (such as directly below the power line) on cloudy days or rainy days in Mao Mao, a strong induced voltage can be generated on the metal frame of the umbrella.
When it is close to the high-voltage line (the distance is evaluated according to the transmission voltage and height of the high-voltage line), the greatest harm comes from some high-intensity frequencies in the 30MHz~ 12GHz band, which can penetrate through non-conductors such as walls and be invisible, especially the electric field. Unless the entire residential building is made into a fully enclosed metal shield.
2. Sound waves of mechanical vibration
It can be said responsibly that any high-voltage line will have mechanical vibration when transmitting current. The main sources of these vibrations are: 1. Changing strong airflow and airflow (large); 2. Thermal noise caused by transmission line impedance in this province (small).
The sound waves produced include infrasound, audible noise and ultrasonic waves. Infrasosound is the most harmful to human body, and audible noise is more harmful to people's psychology.
In addition, high-voltage lines may lead to lightning strikes. Because the high-voltage line is relatively high and the input current is large, lightning strikes are prone to occur. The probability of lightning stroke is based on the Poisson distribution of the angle formed by the point and the conductor perpendicular to the ground, and the probability is the highest in the vertical ground. Theoretically, the probability above 45 degrees is relatively small, and the actual situation depends on the surrounding environment.
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