Why did you have to turn off the TV when there was thunder in the past, but not now?
Why did you turn off the TV when there was thunder in the past, but not now?
In the past, the purpose of turning off the TV during thunderstorms was to prevent the high voltage and high current of lightning from entering the interior of the TV from the power cord and damaging the electronic components. Because in the past, TV sets were purchased by ordinary people using their savings over many years. Radar is a thing that no one knows, and even now there are no voltmeters or ammeters to measure it directly. Its lightning voltage is estimated to be about 100 million volts to 1 billion volts, and the current intensity is 10,000 to 300,000 amps;
When I was playing with desktop computers when I was young, I was once introduced by lightning through the telephone line to remove the computer motherboard. Has been damaged.
In the early days of our country’s TV sets, a component called a varistor was installed at the power input end. The MYG20 series was commonly used and was mainly used to control circuit surge current to protect other electronic components. ; MYG3 and MYG4 series are mainly used for over-voltage protection of communication equipment and frost-free refrigerators; MYH-182, MYH-208 and other models are used for over-voltage and over-current protection of color TVs. It can be said that the overvoltage components installed inside the TV and the computer are powerless against lightning.
It is also a wrong view not to turn off the TV when there is thunder. There is no SPD surge protector installed inside. Without a surge protection device, it is most vulnerable to damage by lightning. The State Grid Corporation of China generally installs lightning arresters and low-voltage surge protectors on its high-voltage/low-voltage lines, and requires that distribution boxes in buildings have surge protectors to minimize the risk of being struck by lightning.
Since 1992, these low-voltage surge protectors were industrial control standard 35mm guide rail snap-on pluggable SPD lightning protection modules represented by Germany and France, which began to be introduced to China on a large scale. Later Integrated box-type power supply lightning protection combinations represented by the United States and Britain have also entered China. In this way, although the thunderstorm is not hit, if it encounters a strong thunderstorm, it may be unable to withstand it. However, some old communities and self-built houses in rural areas often do not understand the dangers of lightning and do not have surge protectors at all. Therefore, in the event of a severe thunderstorm, In severe thunderstorms, it is safer to unplug the power cord.
The harm caused by lightning is one of the serious natural disasters. The residual voltage caused by lightning and induced lightning can still impact electrical equipment, causing short circuits in household appliances, leading to direct losses such as combustion and explosion.
Additional reading
Varistor is the abbreviation of voltage-sensitive resistor and is a non-linear resistive element. The resistance of the varistor is related to the voltage applied at both ends. When the voltage applied to the varistor is within its nominal value, the resistance of the resistor is infinite and almost no current flows through it.
When the voltage across the varistor is slightly greater than the nominal voltage, the varistor quickly breaks down and conducts, and its resistance drops quickly, leaving the resistor in a conductive state. The characteristics of the varistor are: When the voltage applied to it is lower than its threshold value "UN", the current flowing through it is extremely small, equivalent to a closed valve. When the voltage exceeds UN, its resistance becomes smaller, so that This causes the current flowing through it to surge without much change in the impact on other circuits, thereby reducing the impact of overvoltage on subsequent sensitive circuits. Using this function, abnormal overvoltage that often occurs in the circuit can be suppressed and the circuit can be protected from overvoltage damage. What is mentioned above is almost like "a weasel picking up a wife", a small fight.
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Whenever I saw lightning and thunder when I was a child, my parents would come to me and say: Hurry, plug the TV in Unplug.
I believe that many friends have experienced it when they were young. Looking back now, it is also a kind of aftertaste. It seems that this phenomenon is no longer seen.
We used to have to turn off the TV when there was thunder, mainly because the TV we watched at that time had an antenna pole outside, and a bamboo pole had to be placed high on the roof, so that we could receive the signal and see the TV. characters in it.
But with this antenna, when there is lightning, this antenna pole can easily become a lightning receiver. So we just turn off the TV and unplug when it thunders.
Today, network signals for televisions and computers are transmitted through optical fiber communications in metropolitan areas. Except for the covered cables used for household use, there are steel wires. For example, the main material of optical fiber used in cats is silica, which does not contain any conductive metal and is an absolute insulator. Therefore, thunder and lightning have no effect on him.
In the past, when the economy and technology were not developed, and the infrastructure was also very backward, every household would set up a TV antenna on the roof or high outdoors to receive signals. This was like a lightning rod. Now that they have cable TV, there is no need Worried about thunder.
In what year were you born? Young people may not know that in the past, when watching TV, an antenna was used to receive signals. It was connected to an outdoor antenna and the antenna was set up with a wooden pole to get a signal. Thunder can easily draw electricity into the house. Nowadays, all cable TV is available, so of course it’s okay. After all, everyone is watching online TV now. Who still uses cable TV? I haven’t used cable TV in almost 10 years.
1 Because in the past, civilian electricity did not have leakage protection and circuit breaker protection. Some users could directly use a fire and a ground wire for lighting. Since most of them were bungalows in those days, the casing of the electrical appliance was used. There was no ground wire, and electric shock accidents were frequent in those days.
2 Modern people live in high-rise buildings. There are leakage protection and circuit breakers in the residential electricity boxes, and there are good ground wires. The ground wires of residents in high-rise buildings have equipotential connections with steel bars. If there is lightning, It can quickly discharge electricity underground to protect electrical appliances from being struck by lightning.
Thank you
The TV used to have an antenna, but now there is no antenna so there is no need to turn off the TV. In the past, there were few tall buildings, but now there are many tall buildings. Even if you are hit by a thunderbolt, it won't be your turn, so you don't need to turn off the TV. There used to be a lot of trees, but now there are no trees nearby (holly doesn't count), so there's no need to turn off the TV.
The main thing is that Lei likes things that are tall and must be conductors.
Because in the past, transmission and transformation wires below 10 kilovolts were all bare wires, lightning could easily hit the wires and cause high-voltage damage to household appliances in an instant. Today's 10 kV transmission and transformation lines are all insulated, so you are not afraid of thunder.
No matter before or now, it is common for electrical appliances to be damaged during thunder in rural areas, especially before it rains.
No one can tell how much energy there is when lightning is generated. It can break through the air from high altitude and flow into the earth. Think about how terrifying it is.
Nowadays, cities are full of high-rise buildings, and high-rise buildings are equipped with lightning protection devices. Most of them are cables buried underground and not overhead, so the chance of being struck by lightning is very small. However, you should not use electrical appliances during lightning. For the best.
In vast rural areas and cities with overhead wiring, especially in areas frequently struck by lightning. Do not use electrical appliances during thunder and unplug all electrical appliances with semiconductor devices.
If struck by lightning, almost none of the semiconductors in the electrical power supply will be spared, and sometimes the integrated circuit will be broken down, causing the motherboard to be scrapped.
The season of thunder and lightning is here. Please pay attention to lightning protection, especially the rural friends.
I wonder how much the poster understands thunder and lightning? How much does he understand about commercial electricity? Or how much do you understand TV analog signals or current digital signals?
In the 1990s, TV reception signals were mainly analog signals, which required an outdoor receiving antenna. If you want a TV that can watch a lot of TV programs or make the TV programs clear and interference-free, the only way is to set up the outdoor antenna very high. Of course, everything has two sides, pros and cons. The higher the antenna is erected, the more likely it is to attract lightning. Everyone knows that lightning has high voltage and high current, and even now humans cannot utilize it. Household appliances all use 220V mains power. If during a thunderstorm, the high voltage of lightning passes through our outdoor antenna and transmits the high voltage to our electrical appliances, what will be the consequences? It can range from burning electrical appliances to causing personal casualties.
Now, with the improvement of TV signal technology, the analog signals we use have been converted into current digital signals, and the previous cable transmission has become the current optical fiber transmission. (Let me mention here that optical fiber does not have any electricity, only transmits optical signals and is an absolute insulator). With the improvement of technology, our analog signals have been pushed to the stage of history, and the previous outdoor antennas have also become history.
Therefore, it is now impossible for lightning to burn out electrical appliances.
In the past, many bungalows did not have ground wires
There were no lightning rods in the house, but the TV had an antenna
Therefore, the TV had to be turned off during thunder