Why did you turn off the TV when it thundered before, but now it's not used?

Why used to thunder and turn off the TV, but now it's not used?

In the past, in order to prevent the high voltage and current of lightning from entering the TV set from the power line and damaging it, the TV set was turned off by lightning. Because in the past, TV sets were bought by ordinary people with money saved for many years. Radar is a guy nobody knows. Even now, there is no voltmeter or ammeter to measure directly. The lightning voltage is estimated to be about 1 100 million volts ~ 1 100 million volts, and the current intensity is 1 10,000 ~ 300,000 amps.

When I was a child, I played with a desktop computer and was once damaged by lightning coming from a telephone line.

Early TV sets in China were all components called piezoresistors installed at the power input, which were commonly used in MYG20 series, mainly used to control the surge current of circuits to protect other electronic components. MYG3 and MYG4 series are mainly used for overvoltage protection of communication equipment and frost-free refrigerators; MYH- 182, MYH-208 and other models are used for overvoltage and overcurrent protection of color TV sets. It can be said that the overvoltage components installed in TV and computer are powerless against lightning.

It is also wrong to turn off the TV when it thunders. There is no SPD surge protector installed inside, and no surge protector is the most vulnerable to lightning damage. However, lightning arresters and low-voltage surge protectors are generally installed in the high-voltage and low-voltage lines of State Grid Corporation, and surge protectors are also required in the distribution boxes of buildings to minimize the risk of being struck by lightning.

Since 1992, these low-voltage surge protectors, represented by German and French, have been introduced to China on a large scale. Later, the lightning protection combination of integrated box power supply represented by the United States and Britain also entered China. In this way, although it has not been hit by thunderstorm weather, if it encounters strong thunderstorm weather, it will sometimes be unbearable, and some old communities and rural self-built houses often don't know the harm of lightning, and there is no surge protector at all, so it is safer to unplug the power supply in strong thunderstorm weather.

The harm caused by lightning is one of the serious natural disasters. The residual voltage generated by lightning and induced lightning can still impact electrical equipment, which is the direct loss of household appliances such as short circuit, combustion and explosion.

Supplementary reading

Varistor is the abbreviation of varistor, and it is a kind of nonlinear resistance element. The resistance of rheostat is related to the voltage applied across it. When the voltage applied to the rheostat is within its nominal value range, the resistance of the resistor is infinite, and almost no current flows.

When the voltage across the varistor is slightly higher than the nominal voltage, the varistor quickly breaks down and conducts, and its resistance value drops rapidly, making the resistor in a conducting state. The characteristic of rheostat is that when the voltage applied to it is lower than its threshold, the current flowing through it is very small, which is equivalent to a closed valve. When the voltage exceeds UN, its resistance value becomes smaller, which makes the current flowing through it surge and has little influence on other circuits, thus reducing the influence of overvoltage on subsequent sensitive circuits. Using this function, the abnormal overvoltage that often occurs in the circuit can be suppressed and the circuit can be protected from overvoltage damage. Almost all of the above are "weasels picking up their wives", making a fuss.

Happiness lies in contentment. March 2022 13 night in Shanghai.

When I was a child, whenever I saw lightning and thunder, my parents would come over and say, come on, unplug the TV.

I believe many friends have experienced it when they were young. Looking back now is also a kind of aftertaste. It seems that we can't see this phenomenon now.

We used to turn off the TV when it thundered, mainly because there was an antenna pole outside the TV we were watching at that time, and we had to put a bamboo pole high on the roof to receive the signal and see the people on TV.

But it is this antenna. When it thunders, this antenna pole can easily become a lightning receiver. So when it thunders, we turn off the TV and unplug it.

In today's metropolis, the network signals of TV and computer are all transmitted through optical fiber communication. In addition to household leather cables, there are also steel wires. For example, the main material of cat optical fiber is silicon dioxide, which does not contain any conductive metal and is an absolute insulator. So lightning has no effect on him.

In the past, the economy and technology were underdeveloped and the infrastructure was backward. Every household sets up a TV antenna on the roof or outdoors to receive signals, just like a lightning rod. It's cable TV now, so don't worry about thunder.

What year were you born? Young people may not know that they used to watch TV with an antenna to receive signals. It is connected to an outdoor antenna, which is erected with a wooden pole to get the signal. When it thunders, current easily flows into the house. Now it's all cable TV. Of course it doesn't matter. Now I'm talking about watching Internet TV. Whoever still uses cable, I won't need cable for almost 10 years.

1 In the past, there was no leakage and outdoor protection for civil electricity, and some users could directly use fire and ground wire for lighting. Because most of those years were bungalows and there was no grounding wire in the electrical shell, electric shock accidents often occurred in those years.

Modern people live in tall buildings. There are leaks and gaps in the electrical box of the residential area, and there are good grounding wires. The residential grounding wire on the high-rise building has equipotential connection with the steel bar. If there is lightning, it can be quickly discharged underground to protect electrical appliances from lightning.

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There used to be an antenna on TV, but now there is no antenna, so you don't have to turn off the TV. In the past, there were few high-rise buildings, but now there are many high-rise buildings. It's not your turn to recruit the thunderbolt wheel, so you don't have to turn off the TV. There used to be many trees, but now there are no trees nearby (holly is not counted), so you don't have to turn off the TV.

The most important thing is that Lei likes long and tall things, and he has to be a conductor.

Because in the past, transmission lines below 10 kV were bare wires, lightning easily hit the wires and instantly burned household appliances under high voltage. Now 10 kV transmission lines are all insulated and are not afraid of lightning.

No matter before or now, it is common for electrical appliances to be damaged by thunder in rural areas, especially before it rains.

It is estimated that no one can tell how much energy lightning generates. It can penetrate the air from high altitude and flow into the earth. Think about how terrible it is.

Nowadays, cities are all high-rise buildings, and high-rise buildings have lightning protection devices. Most of them are buried cables, and the probability of being struck by lightning is very small, but it is best not to use electrical appliances when it thunders.

In the vast rural areas and cities with overhead lines, especially in areas that are often struck by lightning. Don't use electrical appliances when it thunders. Unplug all electrical appliances with semiconductor devices.

If struck by lightning, all semiconductors in the electrical power supply will be spared, and sometimes the integrated circuit will be broken down, resulting in the scrapping of the motherboard.

Lightning season is coming, please pay attention to lightning protection, especially friends in rural areas.

I wonder how much the landlord knows about lightning? What is your understanding of commercial power? Or how much do you know about TV analog signals or digital signals now?

At that time in the 1990s, TV reception signals were mostly analog signals, so it was necessary to set up a receiving antenna outdoors. If you want to watch a lot of TV programs or make TV programs clear and undisturbed, you can only set the outdoor antenna very high. Of course, everything has two sides, both advantages and disadvantages. The higher the antenna, the easier it is to attract lightning. Everyone knows that lightning has high voltage and high current, and even now humans don't need it. Household appliances are all mains 220V V V. What if the high voltage of lightning is transmitted to the appliances we use through our outdoor antenna in thunderstorm weather? From burning electrical appliances to causing casualties.

Now with the improvement of TV signal technology, the analog signals we use have been converted into digital signals, from wired transmission to optical fiber transmission. Here, optical fiber is an absolute insulator. It has no electricity and only transmits optical signals. With the development of technology, our analog signal has been pushed out of the historical stage, and the previous outdoor antenna has also become history.

So it is unlikely that lightning will burn out electrical appliances now.

In the past, many bungalows did not have grounding wires.

There is no lightning rod in the house, but the TV has an antenna.

So turn off the TV when it thunders.