Electric networks are fixated on the transmission of electricity from source to consumer, which are the main elements of the chain. But besides them, other components are inserted into the electrical circuit, for example, control elements, which include a rheostat or any other device with the same principle of operation. A rheostat device is a conductor of a certain section and length, through which you can find out the resistance of the conductor. Of course, its material is also discussed. By changing the resistance of the device, or rather, the conductor, you can adjust the amount of current and voltage in the network. So, a rheostat is a device that regulates voltage and current.
Device and principle of operation
If we consider the rheostat design, then it is necessary to note several of its main parts:
- This is a ceramic tube;
- a metal wire is wound around it, the ends of which are led to contacts located at opposite ends of the ceramic tube;
- a metal rod is installed above the tube, on one side of which a contact is installed;
- A moving contact is attached to the rod, which electricians call a slider.
Now how does it all work. Pay attention to the picture below.
The first position (a) is the contact (moving) in the middle. This means that the current will only pass through half of the device. The second position (b) indicates that the conductor is fully engaged. That is, its length is maximum, which means that the resistance is maximum, while the current strength has decreased. It is clear that the greater the resistance, the less the current. The third position (c) is the opposite here: the resistance decreases, the current strength increases.
I would like to draw your attention to the fact that the ceramic tube used in the rheostat design is hollow. This is a necessary component that allows the device to cool when passing through a conductor of electricity. We add: it is believed that the safest rheostats are those that are covered with a casing.
How is a rheostat connected to a circuit?
Firstly, this device is connected to the electrical circuit only in series. Secondly, one of the contacts is connected to a slider, with the help of which the amount of current in the circuit is regulated. But it should be noted that this control element can also be used to regulate the voltage in an electrical circuit. Several circuits with one or two resistances can be used here. It is clear that the fewer elements in an electrical chain, the simpler it is.
Rheostats are universal devices. Today they are used not only to control current and voltage. For example, on televisions they are installed to increase or decrease the sound. Yes, and switching channels is indirectly related to them.
And one moment. In electrical diagrams the designation of these devices is as follows:
or such
The first figure shows the connection diagram in more detail, where the red rectangle is the conductor wound onto a ceramic base. The blue line is the contact through which the power wire is supplied. The green arrow is the slider. It is directed to the left, which means that by moving the slider to the left, we reduce the resistance of the conductor. And, conversely, we move the contact to the right, increasing the resistance.
The second drawing is more simplified. It just has a rectangle showing the presence of resistance, and an arrow that shows that this indicator can be changed.
Of course, all this information concerns the simplest elements. But it should be noted that rheostats can be different, it all depends on the place where they should be installed. There are also differences in the underlying conductive material. For example, this could be coal, metals, liquids and ceramics. In addition, the cooling process is carried out by air or using liquids, and this can be not only water.