EVCOME EV charging stations for better life---Top EV charging stations manufacturers & suppliers in China.
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EVCOME EV charging stations for better life---Top EV charging stations manufacturers & suppliers in China.
The normal cables we use are wrapped with a layer of insulation. Single high voltage cables are streaked all the way and have no insulation. Why? The transmission voltage of high-voltage transmission lines is mostly above 1000 volts, and the transmission voltage of some lines is as high as 1000 volts and 50000 volts. If you want to use such wires to wrap the insulation layer, the thickness of the insulation layer of ordinary lines is far from enough. The voltage of the wires in our homes is usually only 220V. As long as they are wrapped with a thin insulating layer to prevent people from contacting the live wire, electric shock can be prevented. But high-voltage equipment is different. People standing a certain distance next to high-voltage equipment will cause electric shock even if they do not touch it. Electric shock caused by high voltage can be divided into step voltage electric shock and high voltage arc electric shock. Stepping voltage electric shock means that if the high-voltage transmission line falls on the ground, the current flows into the ground, and the potential near the grounding point will gradually decrease to a distance, then the person's feet stand on the voltage difference, and the current passes through the human body to cause an electric shock, that is, stepping Electric shock. When people get close to the high-voltage equipment to a certain distance, the high-voltage arc shock will produce arc discharge, that is, you will see a momentary flash, and then the contactor will be knocked down by the high voltage, resulting in injury or even death. Therefore, it is not enough to wrap a layer of household wire insulation for high-voltage transmission lines. According to the safe distance of high-voltage lines touching people is 1mm per 3000 volts, the insulation layer thickness of 500,000 volt lines should be at least 17cm. Such a thick insulating layer will inevitably greatly increase the weight of the transmission line, so for a transmission line of thousands of kilometers, the cost investment will inevitably double. In fact, the easiest way to keep high-voltage lines from harming people is to separate the lines from people by a certain distance. If people can't get close to the line, there will be no electric shock accident. For example, using high-voltage towers to erect transmission lines, people will not get an electric shock when walking under high-voltage lines, so there is no need to wrap insulation on the lines. This method is known in the industry as“air insulation”. Of course, there are also high-voltage lines wrapped in insulation, which we call high-voltage cables. High voltage cables are generally used in areas not suitable for overhead lines, such as underground laying. In addition to thick insulation, high-voltage cables also use copper cores, so the cost of high-voltage cables is more than 10 times that of ordinary overhead lines, and they will not be used unless necessary. .
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