Lesson Notes By Weeks and Term v4 - SHS 1

Lesson Video

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Performance objectives

• Explain power transmission and distribution.
• Identify the consequences of overloading electrical networks.
• Understand how software can simulate power distribution.
• Apply safety measures when working with electricity.

Lesson summary

This lesson explores the fascinating journey of electricity, from the place it is generated, like the Akosombo Dam, to the light switch in our homes and the sockets we use to charge our phones. We often take electricity for granted until we experience a power outage ('dumsor'). Understanding how this system works is crucial for every citizen. We will learn why electricity is transported at very high voltages over long distances and how it is safely brought down to a usable level for our communities. We will also investigate the serious dangers and consequences of illegal connections and overloading our electrical system, issues that directly affect the reliability of power supply in Ghana.

Lesson notes

Part 1: The Journey of Electricity in Ghana

Think of electricity supply like a water delivery system. You have a large source (dam), big pipes to carry water across the country, and smaller pipes to deliver it to individual houses. The electricity grid works in a similar way, through three main stages: Generation: This is where electricity is produced. In Ghana, the main producer is the Volta River Authority (VRA). They operate hydroelectric dams (Akosombo and Kpong), thermal plants (using gas), and solar plants. At this stage, electricity is generated at a moderately high voltage, for example, around 16,000 Volts (16 kV). Transmission: This is the process of moving large amounts of electricity over long distances, from the power plants to major substations near towns and cities. This is the job of the Ghana Grid Company (GRIDCo). You can see their work in the very tall metal towers (pylons) that carry thick cables across the country. Transmission is done at extremely high voltages, such as 161,000 Volts (161 kV) or even higher. We will soon learn *why*. Distribution: This is the final stage where electricity is delivered to consumers like our homes, schools, and factories. The Electricity Company of Ghana (ECG) manages this in the southern part of Ghana, while the Northern Electricity Distribution Company (NEDCo) manages it in the northern regions. They take the high-voltage power from GRIDCo substations and 'step it down' to safer, lower voltages. The wooden or concrete poles you see in your neighbourhood with smaller transformers on them are part of the distribution network. The final voltage delivered to our homes is typically 230 Volts.

Summary Table:

| Stage | What Happens | Key Company | Voltage Level | Analogy | | :--- | :--- | :--- | :--- | :--- | | Generation | Electricity is produced. | VRA | Medium (e.g., 16 kV) | The Akosombo Dam (source) | | Transmission | Bulk power moved long distance. | GRIDCo | Very High (e.g., 161 kV) | Huge pipes from dam to cities | | Distribution | Power delivered to consumers. | ECG / NEDCo | Low (230 V) | Smaller pipes to individual houses | Part 2: The Science of High-Voltage Transmission

Evaluation guide

• Apply the concept of power transmission and distribution in electricity supply.
• Experiential Learning:
• Demonstrate using videos, the consequences of overloading the distribution network
• through illegal connections.