SCHUKO plugs consist of a plug and a corresponding socket. The SCHUKO plug has two round contact pins with a diameter of 4.8 mm and a length of 19 mm. These are the outer conductor and neutral conductor, which have a distance of 19 mm from each other. A third pole, the protective contact, dissipates fault currents that can occur when the electrical circuit is closed by the other two poles. Therefore, the connection with the protective contact must be „leading“, which means that it has to be made before the connection of all other contacts and interrupted last when the connections are disconnected. In the case of the SCHUKO plug, this is done via contact surfaces on the plug side and the corresponding contact springs of the corresponding socket.
The SCHUKO system is designed for high power, namely voltages from 220 V to 240 V (nominal voltage: 230 V) at 50 Hz. The plugs, sockets and extension cords are usually designed for 16 A current, which corresponds to a power of 3,680 W at 230 V.
Starting with the first constructive approaches to protective plugs and sockets in the 1920s, their practical realization and application in electrical installations, regulations and tests on plug and socket systems have been developed to ensure a comprehensible safety standard.
The „Regulations, rules and standards for the construction and testing and installation material up to 750V (KPI 1928)“ were the first forerunners of today’s series of standards DIN VDE 0620. The first edition of DIN VDE 0620 as „VDE0620i: 1959-07“ has continuously developed up to the current edition DIN VDE 0620-1:2021-02, which can be obtained from DIN Deutsches Institut für Normung e. V. (German Institute for Standardization).
Attention is especially paid to user safety, also for certain target groups, e.g. children. The SCHUKO socket with integrated „shutter“ adds an extra layer of product safety as it is designed to stay closed until the correct plug is inserted. This provides increased protection against contact and reduces the risk of people touching live parts and possibly receiving an electric shock as a result.
In all cases, geometric backward compatibility has to be ensured so that all SCHUKO- and EURO- plugs already on the market today, can also be contacted safely in the future.