Sources of electrical energy: description, types and features

The sources of electrical energy in each locality differ in the way they are obtained. So, in the steppes, it is more expedient to use the force of wind or transform heat after burning fuel and gas. In the mountains, where there are rivers, dams are built and the water sets in motion giant turbines. Electromotive force is obtained almost everywhere due to other natural energies.

Where does the power of consumers come from?

Sources of electrical energy receive a voltage after the conversion of wind force, kinetic motion, water flow, the result of nuclear reaction, heat from burning gas, fuel or coal. Widely used are thermal power plants, hydroelectric power stations. The number of nuclear power stations is gradually decreasing as not entirely safe for people living nearby.

A chemical reaction can be used, these phenomena we observe in the batteries of cars and household appliances. Batteries to phones work on the same principle. Windmills are used in places with constant wind, where the sources of electrical energy contain in the construction of a conventional high-power generator.

To power the whole city, sometimes one station is not enough, and the sources of electrical energy are combined. So, on the roofs of houses in warm countries, solar batteries are installed, which feed separate rooms. Gradually, environmentally friendly sources will replace stations that pollute the atmosphere.

In cars

The battery on the transport is not the only source of electrical energy. The car's circuits are designed in such a way that during the movement the process of converting the kinetic energy into electric energy begins. This is due to a generator in which the rotation of the coils inside the magnetic field generates the appearance of an electromotive force (EMF).

The current starts charging in the network, charging the battery, the duration of which depends on its capacity. Charging starts immediately after the engine starts. That is, energy is produced by burning fuel. The latest developments in the automotive industry have made it possible to use the EMF source of electrical energy for traffic.

In electric vehicles, powerful chemical batteries produce a current in a closed circuit and serve as a power source. Here, the reverse process is observed: the EMF is produced in the coils of the drive system, which causes the wheels to spin. The currents in the secondary circuit are huge, proportional to the speed of acceleration and the weight of the car.

Principle of operation of a coil with a magnet

The flowing current through the coil causes the appearance of an alternating magnetic flux. It, in turn, exerts a magnifying force on the magnets, which causes the frame with two different-polar magnets to spin. Thus, the sources of electrical energy serve as a node for the movement of cars.

The reverse process, when the frame with the magnet rotates inside the windings, due to the kinetic energy makes it possible to convert the alternating magnetic flux into the EMF of the coils. Further, voltage stabilizers are installed in the circuit, which ensure the required parameters of the supply network. By this principle, electricity is generated in hydroelectric power stations, thermal power plants.

EMF in the circuit appears in the usual closed circuit. It exists as long as a potential difference is applied to the conductor. Electromotive force is needed to describe the characteristics of the energy source. The physical definition of the term sounds like this: the EMF in a closed circuit is proportional to the work of external forces that move a single positive charge through the entire body of the conductor.

The formula E = I * R - resistance takes into account the total, formed from the internal resistance of the power source and the results of the addition of the resistance of the feed section of the circuit.

Restrictions on the installation of substations

Any conductor, through which current flows, generates an electric field. The energy source is the emitter of electromagnetic waves. Around powerful installations, at substations or near generator sets, there is an impact on human health. Therefore, measures were taken to restrict the construction of objects near residential buildings.

At the legislative level, fixed distances to electrical facilities are established, beyond which the living organism is safe. The construction of powerful substations near houses and on the route of people is forbidden. Powerful installations must have fences and closed entrances.

High-voltage lines are mounted high above the buildings and are taken out of the settlements. To exclude the effect of electromagnetic waves in a residential area, energy sources are covered by grounded metal screens. In the simplest case, a wire net is used.

Units

Each value of the source of energy and the chain is described by quantitative values. This facilitates the task of designing and calculating the load for a particular food. The units of measurement are related by physical laws.

The following units are set for power supply values:

• Resistance: R - Ohm.
• EMF: E is the volt.
• Reactive and impedance: X and Z are ohms.
• Current: I - ampere.
• Voltage: U - volts.
• Power: P - Watts.

Building serial and parallel power schemes

Calculation of the circuit is complicated if a connection of several types of electric power sources is used. The internal resistance of each branch and the direction of the current through the conductors are taken into account. To measure the emf of each source separately, it is necessary to open the circuit and measure the potential directly on the terminals of the supply battery with a voltmeter.

When the circuit is closed, the device will show a voltage drop, which is of a lower magnitude. Several sources are often needed to obtain the necessary nutrition. Depending on the task, several types of connections can be used:

• Consistent. The EMF of the circuit of each source is added up. So, when using two batteries with a nominal value of 2 volts are obtained as a result of the connection of 4 V.
• Parallel. This type is used to increase the capacity of the source, respectively, there is a longer battery life. The EMF of the circuit does not change with this connection at equal battery ratings. It is important to observe the polarity of the connection.
• Combined connections are rarely used, but in practice they are encountered. The calculation of the resulting EMF is performed for each individual closed area. The polarity and direction of the current of the branches are taken into account.

Power supply wiring

The internal resistance of the source of electrical energy is taken into account to determine the resultant EMF. In general, the electromotive force is calculated by the formula E = I * R + I * r. Here, R is the resistance of consumers, and r is the internal resistance. The voltage drop is calculated from the following relationship: U = E - Ir.

The current flowing in the circuit is calculated according to the Ohm's law of the complete circuit: I = E / (R + r). Internal resistance can influence the current. To avoid this, the source is selected for loading according to the following rule: the internal resistance of the source should be much less than the total overall resistance of consumers. Then it is not necessary to take into account its magnitude due to a small error.

How to measure the ohms of the supply network?

Since the sources and receivers of electrical energy must be coordinated, the question immediately arises: how to measure the internal resistance of the source? After all, an ohmmeter does not connect to contacts with the potentials available on them. To solve the problem, an indirect method of taking indices is used - values of additional quantities will be needed: current and voltage. The calculation is made by the formula r = U / I, where U - voltage drop on the internal resistance, and I - current in the circuit under load.

The voltage drop is measured directly at the terminals of the power supply. A resistor of known denomination R is connected to the circuit. Before measuring, it is necessary to fix the EMF of the source with the open circuit - E. Then connect the load and record the readings - U of the load. And current I.

The required voltage drop on the internal resistance U = E - U load. As a result, we calculate the required value r = (E - U load) / I.