Electrical engineering is all around us. It is impossible to imagine modern society without electrical appliances. Therefore, it is quite understandable that every person in his daily life interacts with appliances in one way or another: opening the refrigerator, pressing the elevator call button, turning on the lighting in the room, etc.
The fine line of gradation
Conventionally, all existing electrical equipment can be divided into two categories according to the method of interfacing with the power grid:
- Stationary, which is connected to the power source with a cable and a permanent connection. Of course, if you have tools, you can turn off, but only in emergency situations. An example would be equipment in a factory.
- Relatively mobile, allowing you to disconnect from the power source without the use of specialized devices. This group includes almost all household electrical appliances. Their distinctive feature is the plug.
What is a plug
Everyone has come across sockets and power plugs. However, few people understand where the term "plug" comes from. Actually everythingsimply. The word "plug" is of German origin. And it means nothing more than a cork. Indeed, the plug, being in the socket, seems to clog the holes of the latter. Hence the term. Well, the additional word "fork" appeared due to a distant resemblance to the famous cutlery. Of course, the tasks of this device are completely different, although, it is worth recognizing, there are real plastic plugs for sockets on the market that protect curious children from accidental electrical injury.
From theory to practice
In simple terms, what a power plug is, it is a device designed to allow a secure plug connection to be made with a specially designed power outlet.
The old-timers remember that earlier this type of connection was used even where it is now impossible to even think about it. So, in the days of the Soviet five-year plans, special designs of lamps were used everywhere in the lighting networks, which made it possible to disconnect the block with the cartridge and the lamp by simple manipulation without tools, leaving on the line … a plug socket. True, its design was somewhat different from the solutions familiar to the eye of a modern person. Now, of course, cable runs are trying to separate as much as possible, so lighting circuits, as a rule, do not allow significant power to be transmitted.
Plug device
There are several variants of this elementdetachable connection. So, there are special solutions designed to connect sufficiently 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 like, for example, a table lamp plug.
Externally, these are two metal (copper or chrome) rods placed in parallel at a certain distance from each other and located in a housing made of dielectric material. Inside, each of them has a bolted or other clamp designed for connecting conductive conductors and grounding. Through such a system, electricity is supplied to the device through a cord (cable). The case can be collapsible, in which case its parts are assembled together with a screw. There are also monolithic modifications. The thickness of the rods and the method of making the earthing contact are determined by the standards. So, speaking about what a plug is, one cannot help but point out a misconception common in the countries of the former USSR, according to which there are two types of power 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 quite large products that necessarily contain a grounding contact or rod in the design. The holes of the socket are deepened in such a way that when the plug is turned on, it is impossible to accidentally touch the half-extractedrods of the latter. Plug-in connection using CEE 7/4 is rated for 16 A and 230 V. The name "euro" was given due to the fact that in Soviet times, appliances from the GDR and Czechoslovakia were supplied with just such plugs.
Actually, 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 like, know all the features of this type of design. For the rest, let's explain: the euro plug consists of two rods with a thickness, like that of Soviet (ordinary) plugs, located in a thin monolithic case made of dense rubber. There is 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 outermost parts about 5 mm long exposed. These euro plugs are designed to connect low-power equipment, such as table lamps. The allowable current is 2.5A, although there are modifications for 5A.
Repairability
The plug design of a table lamp used in mass production does not allow for acceptable repairs in case of damage. Although such monolithic plugs can be cut and the 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 monolithicsolutions. In case of damage, the network cable is cut off as close as possible to the plug, stripped, the grounding conductor is determined and connected to a new collapsible plug.
