Mains voltage

The main parameters of the AC network - voltage and frequency - vary in different regions of the world. In most European countries, the low mains voltage in three-phase networks is 230/400 V at a frequency of 50 Hz, and in industrial networks 400/690 V. In North , Central and partially South America, the low mains voltage in networks with a divided phase is 115 V at frequency of 60 Hz.

A higher mains voltage (from 1000 V to 10 kV) reduces losses during electric power transmission and allows the use of electrical appliances with greater power, however, at the same time, it increases the severity of the consequences of electric shock to unprepared users from unprotected networks.

To use electrical appliances designed for one mains voltage, in areas where another is used, appropriate converters (for example, transformers ) are needed. For some electrical appliances (mainly specialized, not related to household appliances), in addition to voltage, the frequency of the mains also plays a role.

Modern high-tech electrical equipment, usually containing pulsed voltage converters , can have switches for various values ​​of the mains voltage or it does not have switches, but it allows a wide range of input voltages: from 100 to 240 V at a nominal frequency of 50 to 60 Hz, which allows you to use these electrical appliances without converters in almost any country in the world.

Electricity generators generate alternating current of industrial frequency (in Russia - 50 Hz). In the vast majority of cases, three-phase current is transmitted via power lines, increased to high and ultra-high electric voltage with the help of transformer substations , which are located near power plants.

According to the interstate standard GOST 29322-2014 (IEC 60038: 2009) , the mains voltage must be 230 V ± 10% at a frequency of 50 ± 0.2 Hz ^[1] (phase-to-phase voltage 400 V , phase-neutral voltage 230 V, four-wire switching circuit “ Star ”), note “a)” of the standard reads: “However, 220/380 V and 240/415 V systems continue to be used.”

Four-wire (three phase wires and one neutral (zero) wire ) power lines (overhead or cable power lines) with an interphase voltage of 400 volts are connected to residential buildings (on rural streets). Input machines and electricity meters are usually three-phase. A phase wire, a neutral wire, and possibly a protective earth or ground wire, are connected to a single-phase outlet; the electric voltage between the "phase" and the "zero" is 230 volts .

In the rules for the installation of electrical installations (PUE-7), the value 220 continues to appear, but in fact the voltage in the network is almost always above this value and reaches 230-240 V, varying from 190 to 250 V.

Rated voltage of household networks (low voltage): Russia (USSR, CIS)

Until 1926, the Technical Department of the IRTO , which only issued rules for safe operation, was engaged in the technical regulation of general-purpose electrical networks. When examining the networks of the RSFSR before creating the GOELRO plan, it was found that at that time almost all possible voltages of electric currents of all kinds were used. Since 1926, the standardization of electric networks was transferred to the Committee for Standardization under the Council of Labor and Defense (Gosstandart) , which issued standards for the used nominal voltages of networks and equipment. Since 1992, the Interstate Council for Standardization, Metrology and Certification has been issuing standards for the electric networks of countries belonging to the EEC / OEC .

Notes "P"

1. ↑ The Joint-Stock Company of Electric Lighting of 1886 used this rating (voltage at the terminals of the transformer 133 V), which was reflected in OST 569. As a result of harmonization with IEC recommendations in the standard voltage scale GOST 721, it was replaced with a nominal value of 3 × 127 V , but it was allowed to preserve the existing installations 3 × 120 V. In fact, the networks of those large cities that used it already switched to the “ star ” with ratings of 127/220 V and 220/380 V.
2. ↑ The rating of three-phase alternating current 230/400 V, starting from OST 569, 1928, was preferred for current sources (generators and transformers).
3. ↑ ^{1 2 3 4} The use of high voltage current above ± 225 V or above ∼110 V was prohibited in household networks that do not require qualified personnel.
4. ↑ Initially, in the first phase of the GOELRO plan, it was planned to build 120/210 V networks, on the basis that 3 × 120 V ( triangle ) was used in the networks of some large cities, however, during implementation, 127/220 V networks were built.
5. ↑ 1928-1931 Vitebsk, Vyazma, Bobruisk, Rylsk, Rossosh, Zlatoust, Kamyshin, Stone, Krasnoyarsk, Chita, Ostrogozhsk, Starobelsk, Chuguev, Krasnograd, Khmelnik, Kupyansk, Proskurov, Chervonoe ... and others. See: Geiler LB 110 or 220 V in distribution networks of populated areas // Electricity . - 1933. - No. 9 . - S. 39 .
   Subsequently, all major new electrical networks of the USSR were created on 220/380 V.
6. ↑ 1932-40, Lenenergo, transition of old 3 × 120 V networks to 127/220 V. See: B. Aisenberg Manuilov R.E. Grounding neutral neutral urban cable network low voltage // Electricity . - 1940. - No. 11 . - S. 54 .
7. ↑ 1936-47, Mosenergo, transition of selected areas of old networks 3 × 120 V to 127/220 V. See: Plyusnin K.L. Low-voltage closed grid in the Moscow cable network // Electricity . - 1937. - No. 22 . - S. 7 . , and Kulikovsky A.A. System of urban distribution networks of low voltage with artificial neutral points // Electricity . - 1947. - No. 9 . - S. 45 .
8. ↑ In other standards related to industrial applications, for example, GOST 185-41, the rating 127/220 V remained unavailable for new products.
9. ↑ ^{1 2 3} Standards GOST 5651 - “Household radio receiving equipment”, in particular, determined the ratings of the power supply voltage of radio receivers.
10. ↑ ^{1 2} 1950, the beginning of the transfer of the low-voltage network from 127 V to 220/127 V and the use of voltage 380/220 V to power the new residential areas of Moscow. See: Zuev E.N. . Moscow windows unquenchable light (unopened) .
11. ↑ 1970-79, Kiev, Leningrad and Kharkov mainly switched to 220/380 V. Although separate houses in which the transition did not end were found later.

In different regions, sockets and plugs of different types are used.

• List of Standards for Plugs

The quality of electrical energy - its electrical voltage and frequency must be strictly observed.

• Electrical network

• GOST 29322-92 Standard voltages
• Information on the used mains voltage and sockets for different countries of the world
• North american versus european distribution systems