Electrical energy accompanies us at every step. Without it, the life of any person is unthinkable. Throughout our lives, we in one way or another are faced with the manifestations of electricity. This happens more densely, as a rule, when electrical appliances break down. And in order to understand their structure and circuits, it is useful to know that alternating and direct currents are designated as AC and DC currents.
Content
- Sources of electrical energy
- Designations on diagrams and in devices
- DC voltage applications
Sources of electrical energy
Initially, the sources of electricity were only disposable chemical galvanic cells. In the future, reusable batteries appeared. It is noteworthy that the polarity of chemical sources is not able to change by itself. In order to obtain constant voltage generators are used on an industrial scaleand sometimes solar panels.
Electronic equipment, in turn, is powered from an alternating voltage network, and power supplies are used to obtain constant voltage. To the required indicators, the alternating current is reduced using transformers and subsequently rectified. In this case, the ripple frequency is reduced by smoothing filters, stabilizers and voltage regulators.
In the modern world, switching power supplies are common. In them, the ripple frequency of the output electricity is smoothed out by integrating elements. They concentrate electrical energy and transfer it to the load. The result is the required constant voltage.
Electrolytic capacitors can also condense electrical energy. When such a capacitor is discharged, an alternating current appears in the external circuit. If it is discharged through a resistor, then a gradually decreasing (unidirectional) alternating current occurs. When using an induction coil, a bi-directional alternating current is generated in the circuit. Electrolytic capacitors can have enormous capacitancereaching hundreds of microfarads. When such capacitors are discharged through a large resistance, electricity decreases more slowly and a constant voltage already flows in the external circuit.
There are also combinations of capacitors and chemical sources - supercapacitors. They have the ability to store and release a significant amount of electricity. Electric vehicles are a typical example.
Designations on diagrams and in devices
It is generally accepted that the direction of electricity goes from a contact with a plus sign to a contact with a minus sign.
Places with high potentials are called "positive pole" and are indicated by a + (plus) sign. Points with lower potentials, respectively, are called "negative pole" and they are denoted by the sign - (minus).
Initially, it was assumed that the electrical insulation of positive wires is red, while wires with a minus sign are painted blue or black.
Symbols on electrical appliances: - or =. Unidirectional electricity (including direct) is indicated by the Latin alphabet DC, or the Unicode symbol is used - U + 2393.
The abbreviations AC and DC are firmly rooted in everyday life and are used along with the usual names "variable" and "constant":
- designation of constant voltage (-) or DC (Direct Current);
- alternating current sign (~) or AC (Alternating Current) - designation of alternating current.
DC voltage applications
The use of constant voltage allows the transmitted electrical energy to be increased and then transfer it between power systems that use alternating current of different frequencies (for example, 50 and 60 hertz).
Direct current is also actively used in transport. Constant excitation motors are used in various mechanisms:
- electric locomotives;
- electric trains;
- trams;
- trolleybuses;
- lifts, etc.
Not without constant tension in other areas of science and technology. It is widely used in this way:
-
In almost all electronic circuits as a power supply. - Galvanic cells and batteries charge electronic devices: flashlights, toys, batteries in tools and others.
- In industrial electrolytic plants, for example, aluminum, magnesium, potassium, chlorine are obtained from solutions and molten salts.
- In electroplating and electroplating.
- For electric arc and electric gas welding.
- In the on-board networks of cars.
- On some types of ships - icebreakers, submarines, diesel-electric ships.
- In medicine. For example, electrophoresis is the introduction of drugs into the body using electricity.
Electricity accompanies us everywhere: at work and at home. It is scary to imagine even for a minute what will happen to humanity if it suddenly loses its electrical energy.
