Why do we have 220 volts in the outlet?
Different countries have different mains voltage standards. In the USA, 110 V, in Japan 100 V, in Europe and in our country, the voltage has recently been raised to 230 V (± 10%) - GOST 29322-2014 (probably at new substations). Why are names such values, and not rounded to nice numbers, for example: 200 V, 250 V?
Some experienced electrician will say that 220 V is the voltage between phase and zero in a three-phase network or: 380: √3 (380 / 1.73). But why then exactly 380 V, and not 400 V or 350? And why in some countries the voltage is two times lower than European standards? It's all about the history of the development of electricity.
One of the first mass-produced electrical appliances was the electric lighting lamp. They used carbon rods and threads. In the west - Edison lamps. In Russia - Lodygin lamps. And it was experimentally found that the optimal voltage for the operation of such lamps will be 100 V.
Higher - lamp life will be short, lower - lamp is too dim. Because Edison worked with direct current, the losses in the network were significant. At power plants, it was necessary to take this into account and issue 110 V. So, this standard has remained in the United States to this day.
In order to power more devices, two phases of 110 V each began to be introduced into houses. Only one with a minus, and the second with a plus. Later, with the transition to alternating current, it remained as two phases. In the US, there is now 220 V, but in the basements of apartment buildings and in a three-phase network for powering washing machines, for example. It's like with us - when you connect two phases of 220 V and zero, you can get 380 V.
Some of the people of the older generation will remember that there used to be a 127 V standard in the USSR. And in 1960 g. everything was switched to 220 V. What is the reason for this? This is due precisely to the fact that AC 220: √3 = 127 V was launched through the original power grids intended for direct current 220 V (two phases). The merit of Nikola Tesla, who invented the principle of transmission of alternating electric current. At the same time, losses were significantly reduced or the wiring could have a smaller section.
I remember my father and grandfather had electric shavers that could be switched from 127 V to 220 V. Then I did not understand why there was a 127 V mode in the device, if the house was 220 V.
The power of electrical appliances grew, and so did their number. It was necessary either to increase the cross-section of the wiring (moreover, by 4 times), which is very expensive, or to increase the voltage while maintaining the cross-section of the wires (to reduce the current). Which they did in 1960. - raised the voltage on one phase to 220 V. The losses remain the same, but the power can be transmitted more.
The transition was haphazard. In some houses before 1975 the voltage remained 127 V. Hence some devices with dual voltage supply. How many stories were there when residents disabled household appliances intended for a 127 V network, including them in 220 V.
Why the US did not increase the voltage in the network (in phase) is a question. After all, you have to lay increased wiring cross-sections. Although, they have a frequency of 60 Hz in the network. This reduces the weight of the transformers. It is believed that in the United States, leaving the 110 V standard, manufacturers cut off the supply of imported electrical equipment from Europe and allowed their industries to develop. But on the other hand, this entails high wiring costs. Also surprising is the 100 V standard in Japan, where the production of electronics is developed.
A separate topic is the standards of plugs and sockets. There are 13 main species in the world. But this is a topic for a separate article.
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