What's the difference of AC110~127V and AC220~240V ?

Introduction: As we all know, the voltage of electricity used by residents in our country is 220~240 volts. Not only our country, there are still many countries in the world that use 220V~240V AC. However, the question is not over yet: Why doesn’t our country use 110~127V AC like the United States? My friends generally think that if the voltage is lower, it seems safer.

*220V and 110V are both high-voltage electricity and are equally dangerous

*220V is more efficient than 110V, AC power is more efficient than DC power

*220V is used in more countries than 110V

*Why doesn’t the US switch to 220V?

The degree of damage caused by electricity to the human body mainly depends on the size of the current passing through the human body and the duration of electricity. Whether it is 110 volts or 220 volts, it is not a safe voltage, and short-term contact may cause casualties. Getting an electric shock is similar to jumping off a building. The results are the same on the 10th and 20th floors. Generally, the safe voltage of the human body is 36 volts. Only if the voltage is lower than this value, the human body will not have problems if it comes into contact in the short term. It can be seen that the 110-volt voltage used in the United States has nothing to do with safety.

Under the same electrical power, the current in a 220-volt AC circuit is half that of a 110-volt circuit. The current in the conductor is small, so the wire does not need to be too thick, which can save transmission materials. When current flows through a wire, the wire generates heat due to resistance, and this heat loss reduces power transmission efficiency. According to Joule's law, if the current in the conductor differs by half, the heat loss will differ by 4 times, which will greatly reduce the power transmission efficiency.

110 volts is not safer than 220 volts, but 220 volts can improve power transmission efficiency, so 220 volts is better than 110 volts. Especially for long-distance power transmission, in order to improve power transmission efficiency, it is even more necessary to use ultra-high voltage.

It is for this reason that most countries around the world use 220 volts, which can improve power transmission efficiency. Soviet technical standards came from Europe. In the early days of the founding of the People's Republic of China, many of our country's industrial technologies came from the Soviet Union, so the power standards were also inherited from the Soviet Union.

Speaking of electricity, this goes back to the classic AC-DC war in history, starting with the two male protagonists. In the early days of electricity use, Edison invented direct current, and his subsidiary General Electric Company first used 110V voltage to supply direct current to customers in the United States. Later, Tesla invented the 3-phase 240V AC, but for safety reasons he also reduced the voltage to 110V. Due to its advantages such as smaller long-distance transmission losses, his alternating current system eventually defeated Edison's direct current and became the power supply standard in the United States with the funding of Westinghouse Electric Company.

The electric power revolution originated in Europe and the United States. The reason why the United States adopts 110 volts is related to the history of the development of their electric power industry. Before the widespread application of alternating current, humans first used direct current, and electric lights were also the earliest electrical appliances popularized by humans. The practical electric light was invented by the American Edison, and Edison's electric power company dominated the U.S. power industry at the time. The carbon filament incandescent light bulbs at that time had the best luminous efficiency at a voltage of 110 volts, so the voltage of electricity used by American residents at that time was generally 110 volts.

Tesla discovered that alternating current (under the conditions at the time) was more efficient than direct current in power transmission. Finally, it was recognized by everyone, and alternating current replaced the dominant position of direct current. Since the United States adopted the 110-volt power supply standard very early, subsequent AC power also adopted the 110-volt standard.

Because the United States was one of the first countries in the world to popularize electricity applications at that time, and the popularity was very early and very deep, which made it very difficult to change the power standards in the future, so the U.S. power system still maintains the tradition of 110 volts. .

It's not that the United States doesn't want to change this status quo, but the cost of replacing standards is relatively high and the amount of work is relatively large, which cannot be solved with a piece of paper. If we want to change the standards, the U.S. power system and the electrical equipment in residents' homes will need to undergo major changes. Moreover, the United States still belongs to a federal system, and the standards among states are not completely uniform.

However, in the context of globalization, some smart international companies may have noticed the voltage differences between countries. Therefore, many electrical appliances are designed with adaptable voltages, that is, they can be suitable for voltages of 110 to 240V, such as Haier color TVs. The floating range is marked: AC 90~260V, 50Hz, so it can be used as usual under the voltage of 90~260V.

Of course, if you often go abroad, travel agencies generally recommend that you bring your own travel conversion plug and travel transformer when going abroad

written by Jack Hui 

19th Asian Games Supplier | Guardian of Public Health, Food Safety and Livable Environment