Electrical engineering is everywhere around us. Without electrical appliances it is impossible to imagine a modern society. Therefore, it is understandable that each person in his daily life somehow interacts with devices: opening the refrigerator, pressing the elevator call button, including lighting in the room, etc.
Fine line of gradation
Conventionally, all existing electrical equipment by the method of interfacing with the power grid can be divided into two categories:
- Stationary, which is connected to the power source by cable and one-piece connection. Of course, if you have the tools, you can disable it, but only in emergency situations. An example is equipment in production.
- Relatively mobile, allowing without the use of specialized devices to disconnect from the power source. Almost all household electrical appliances belong to this group. Their distinctive feature is the plug.
What is a plug?
Everyone faced sockets and plugs. However, few people understand where the term “plug” came from. In fact, everything is simple. The word "plug" is of German origin. And it means nothing more than a cork. Indeed, the plug, being in the socket, as if clogging the holes of the latter. Hence the term. Well, the additional word "fork" appeared due to the distant resemblance to a well-known cutlery. Of course, the tasks of this device are completely different, although it is worth recognizing that the market has the most real plastic plugs for outlets that protect curious children from accidental electrical injury.
From theory to practice
In simple terms, what is a plug, then this is a device designed to provide the ability to make a safe detachable connection with a specially designed plug socket.
Old-timers remember that earlier a similar type of connection was used even where it is now impossible to even think of such a connection . So, during the Soviet five-year periods, special designs of luminaires were used everywhere in lighting networks, which made it possible, by simple manipulation without tools, to disconnect the unit with the lampholder and lamp, leaving ... a power outlet on the line. True, its design was somewhat different from the decisions customary for the modern human eye. Now, of course, cable routes are trying to divide as much as possible, so lighting circuits, as a rule, do not allow significant power to be transmitted.
Plug device
There are several options for the implementation of this element detachable connection. So, there are special solutions designed to connect fairly powerful electrical equipment to a three-phase network - they use four contacts (three for phases and ground). However, in mass production, a simpler design is used - just such as, for example, the plug of a table lamp.
Outwardly, these are two metal (copper or chrome plated) rods placed in parallel at a certain distance from each other and located in a housing made of dielectric material. Inside each of them there is a bolt or other clamp, designed to connect conductive wires and ground. Through such a system, electricity is supplied to the device via a cord (cable). The housing can be collapsible, in this case its parts are assembled together with a screw. There are also monolithic modifications. The thickness of the rods and the method of execution of the grounding contact are determined by standards. So, speaking about what a plug is, one cannot but point out the common misconception in the countries of the former USSR, according to which there are two types of network plugs (and sockets) - ordinary and euro.
Variety of modifications
The term "euro" is used in relation to the CEE 7/4 standard (Type F, or Schuko) - these are sufficiently dimensional products that necessarily contain a grounding contact or a rod in the design. The outlet holes are recessed so that when you turn on the plug to exclude the possibility of accidental contact with the semi-removed rods of the latter. The plug-in connection using CEE 7/4 is designed for 16 A and 230 V. The name "euro" was given due to the fact that in Soviet times devices from the German Democratic Republic and Czechoslovakia were supplied with such plugs.
In fact, the euro plug really exists. This solution is based on the CEE 7/16 standard. Those who have ever wondered what the plug of a table lamp is, know all the features of this type of design. For the rest, let’s explain: the euro plug is two rods with a thickness, like that of Soviet (ordinary) plugs, located in a thin monolithic case made of dense rubber. No ground contact. The shape is such that such a plug can be easily inserted into an outlet of almost any design. Safety against accidental contact is realized by isolating most of the rods, leaving only the extreme parts about 5 mm long bare. Such euro plugs are designed to connect low-power equipment, such as desk lamps. The permissible current is 2.5A, although there are modifications for 5A.
Maintainability
The device of the plug of the table lamp used in mass production does not allow an acceptable repair in case of damage. Although such monolithic plugs can be cut and internal contacts restored by soldering, after such an operation it is impossible to ensure electrical safety, while maintaining a normal appearance. This applies to all monolithic solutions. If they are damaged, the network cable is cut off as close to the plug as possible, stripped, the grounding conductor is determined and connected to a new collapsible plug.