Understanding Electricity: Generation, Distribution & Applications
Overview of Electricity
Electricity is a secondary source of energy, meaning it’s derived from other primary sources. In many countries, the primary sources for electricity generation include:
- Hydro (51%)
- Gas (34%)
- Coal (9%)
- Oil or other (6%)
Electrical energy accounts for approximately 17% of total energy sources in some countries. Other significant energy sources include:
- Petroleum (38%)
- Gas (26%)
- Firewood (13%)
- Coal (6%)
Electricity is crucial for various production processes, including industry, mining, residential use, and utilities. Its importance in modern society is undeniable.
In Chile, electricity services cover approximately 99% of urban areas and 90% of rural areas.
Stages of the Electrical System
The electrical system generally consists of three stages:
a) Generation
Power generation centers are typically located remotely from population centers due to their need for substantial energy sources and security considerations.
b) Transmission
Since generators are often far from urban areas, power lines are necessary to transmit electricity to these centers. Transmission involves raising the voltage of generated electricity and transmitting it through power grids to consumption centers.
c) Distribution
Distribution companies receive the transmitted energy and distribute it through their networks to end consumers.
d) Final Consumer
End consumers utilize electricity in their production processes or for various applications.
The construction industry, for example, uses electrical energy in various stages, both as an input in production and as a service.
Variable Electric Power
Voltage or Potential Difference
Electrically charged bodies possess an electric potential that allows them to attract or repel other charges within their influence. When two bodies have different electric charges and potentials, electrons flow from the body with higher potential to the one with lower potential. This potential to do work on charges between two potentials is called voltage.
To induce electron flow in a body, a voltage or potential difference is necessary.
Voltage is symbolized by the letter ‘V’ and measured in volts.
Voltage represents the work required to move a specific amount of electric charge.
Technology enables us to impart potential to a conducting body and create a “voltage source.”
Voltage Source
Constant Voltage
A constant voltage source maintains its polarity over time, causing charges to move consistently in the same direction.
Common examples of constant voltage sources include batteries, accumulators, and photovoltaic cells, which generate a potential difference between two polarized terminals through physical-chemical processes.
Any body subjected to a potential difference from these sources experiences charge movement from the positive terminal to the negative terminal.
Alternating Voltage Source
An alternating voltage source provides a conducting body with an electric potential that varies in both direction and magnitude.
This type of voltage source is widely used in industries, residential areas, and commercial settings.
The potential difference is established between bodies with different potentials or between a body with potential and another with zero potential (neutral).
The alternating voltage used in national networks typically corresponds to a sinusoidal signal with a frequency of 50 hertz and a maximum of 311.13 volts.
Electricity Supply (Current)
Electricity supply, or current, refers to the flow of electrons in a conducting body subjected to a potential difference or voltage. It’s represented by the letter ‘I’ and measured in amperes.
Current is defined as the number of charges passing through the cross-section of a conductor per unit of time.
For current to flow, the body under potential difference must be a conductor, meaning it has free electrons that can be readily released when voltage is applied.
Commonly used conductors include copper and aluminum.
Materials that require very high voltages to release electrons are called dielectrics or insulators and are used for electrical insulation.
Electrical Circuit
An energy source produces a potential difference or voltage, supplying the energy needed to move electric charges.
Conductors connect the energy source to the electric charge without significantly affecting its characteristics or behavior. They are typically wires with low electrical resistance.
An electric charge, or load, within the circuit responds to the voltage from the source and transforms electrical energy into another form of energy or a practical effect.
Loads are broadly categorized as motor, light, and heat loads.
Circuit Conditions
a) Closed Circuit
In a closed circuit, the voltage source is directly connected to the load through conductors. Current flows at a controlled level determined by the load.
b) Open Circuit
An open circuit occurs when there’s a break in the conductor, either accidentally or intentionally. No current flows when the connection between the load and the source is interrupted.
c) Short Circuit
A short circuit happens when the terminals or poles of a voltage source are directly connected. This is an undesirable phenomenon that can damage the circuit. Without a load connected to the terminals, the current can rise to extremely high levels, generating excessive heat.
Voltage sources are considered active elements because they provide energy, while loads are considered passive elements because they consume energy.
Components of an Electric Charge (Load)
Loads, where energy transformation occurs, typically consist of three elements:
- Electrical Resistance
- Electrical Inductance (Coil)
- Electrical Capacitance (Capacitors)
Electrical Resistance
Electrical resistance is the opposition a load presents to the flow of electric current. It’s a passive element that dissipates energy as heat.
Resistance is represented by the letter ‘R’ and measured in ohms.
The resistance of a conductor depends on its physical characteristics (conductivity) and length.
A significant aspect of electrical resistance is its variation with temperature, which is defined by the coefficient of variation.
Inductance or Coil
Inductors or coils are circuit components made of an electrical conductor wound into one or more turns. Their primary characteristic is the ability to store energy as a magnetic field. This phenomenon is utilized to generate kinetic energy, making inductors essential in applications like electric motors.
Inductance is symbolized by the letter ‘L’ and measured in henrys.
The inductance of a coil depends on the number of turns, current flow, and magnetic field strength.
Capacitance (Capacitors)
Capacitors are passive electronic components that store electrical energy in an electric field. They consist of two conductive plates separated by an insulator (dielectric).
Capacitance is symbolized by the letter ‘C’ and measured in farads.
The capacitance of a capacitor depends on factors like the surface area of the plates, the distance between them, and the dielectric material’s properties.