Understanding Electrical Current Generation, Transport, and Circuitry

Posted on Feb 13, 2025 in Technology

Electrical Current Generation and Transport

Generation and Transport of Electric Current: Alternators and dynamos transform mechanical energy into electrical energy. Alternators generate alternating current, while dynamos generate direct current.

Electric Current Transport: Transporting electricity requires conductors, which offer some resistance to the passage of electric current. This resistance causes energy loss as heat due to the Joule effect. To reduce losses, the current intensity is reduced by increasing the voltage for transport. Subsequently, the voltage is decreased for safe use by consumers.

Transformers and Energy Measurement

Transformers: A transformer is an electromechanical device that transforms electrical energy by changing the voltage or other characteristics of the alternating current it receives.

Energy Meter: An energy meter records the amount of electrical energy (kWh) consumed in a circuit over a specific period. It consists of a motor that spins an aluminum disc. Higher consumption increases the disc’s speed. A counter tracks the number of revolutions to calculate the total energy consumed.

Circuit Protection and Safety

Control and Protection Devices: These devices protect:

  • The circuit from overcurrent, overvoltage, and short circuits.
  • People and animals from direct or indirect contact with electricity.

Elements of a Protective System

  • ICP (Circuit Breaker): Installed by the power company to limit power consumption according to the contracted amount. It trips if the power exceeds this limit. It is sealed and separate.
  • IGA (Main Switch): Cuts off all circuits in the home.
  • Differential (RCD): Quickly disconnects the entire electrical installation when a current leakage to ground is detected, preventing electric shock from indirect contact or conductor faults. A differential’s sensitivity is the leakage current value at which it trips. In residential settings, high-sensitivity differentials (30mA) are used, as leakage currents above this level are considered dangerous.
  • PIA (Miniature Circuit Breaker): Protects individual circuits and conductors from overloads and short circuits. Each circuit in the home has its own PIA, each with a maximum current rating (e.g., 10A, 15A, 20A).

TT Earthing System: The ground provides a low-resistance path to drain any leakage current, closing the circuit to ground. It consists of a metal rod buried in the soil, mixed with salt, and connected to the electrical system via a cable. This protects users by bypassing current in case of insulation failure in live conductors.

Electrical Quantities and Ohm’s Law

Electricity and Electronics – Electrical Quantities:

  • Voltage (V): The potential difference between two points, measured in volts. It is required to drive current through a conductor.
  • Current Intensity (I): The amount of electric charge flowing through a conductor per unit of time, measured in amperes.
  • Resistance (R): The opposition a material offers to the flow of electric current, limiting or controlling the current flow. It is measured in ohms. For a conductor, its value is determined by its resistivity, length (L), and cross-sectional area (S in mm2).

Ohm’s Law

Ohm’s Law is the formula that relates voltage, current, and resistance: V = IR.

  • Energy (E): The capacity to do work, measured in joules (J), kilowatt-hours (kWh), and calories (cal).

E = IVT (Intensity, Volts, Time)
E = PT (Power, Time)
E = I2RT (Current, Resistance, Time)

Time (sec)
1J = 0.24 cal
1 cal = 4.18 J
1 kWh = 3.6 x 106 J

  • Power (P): The rate at which energy is used, stored, or transported, measured in watts.

P = W/T
P = I2R
P = V2/R

Series and Parallel Circuits

Series Circuit: A voltage divider circuit. Not typically used to connect receiving elements. Series connections are used when control, regulation, or protection is required. The total equivalent resistance is the sum of all individual resistances. The total voltage is also the sum of all individual voltages.

Parallel Circuit: The voltage is constant across all components. This circuit configuration is commonly used to connect receivers. The reciprocal of the total resistance is the sum of the reciprocals of individual resistances. The total current is the sum of the individual currents. Vtotal = V1 = V2 = V3.

Mixed Circuit: A combination of series and parallel circuits. For example, multiple receivers can be connected in parallel, and one or more of them may be protected or regulated by components connected in series.