Lesson Notes By Weeks and Term v4 - SHS 1
ELECTRICAL SYSTEMS DESIGN
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ELECTRICAL SYSTEMS DESIGN
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Subject: Applied Technology
Class: SHS 1
Term: 1st Term
Week: 20
Grade code: 1.3.1.LI.3
Strand code: 3
Sub-strand code: 1
Content standard code: 1.3.1.CS.1
Indicator code: 1.3.1.LI.3
Theme: ELECTRICAL AND ELECTRONIC TECHNOLOGY
Subtheme: ELECTRICAL SYSTEMS DESIGN
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We all use electricity every day in Ghana – to charge our phones, watch TV, light our homes, and power our schools and businesses. But have you ever wondered how this electricity travels from the big dams like Akosombo or Bui, or the power ships at Tema, all the way to the socket in your wall? Sometimes, we experience "dumsor" or power outages, and often this is related to problems in the system that brings the power to us. This lesson will uncover the journey of electricity. Understanding this journey is crucial for appreciating why we need to use electricity safely and responsibly, and how issues like illegal connections can damage the system for everyone.
This section breaks down the entire journey of electricity from its creation to its use in our homes. Stage 1: Power Generation This is where electricity is created. In Ghana, our main sources are: Hydroelectric Power: Using the force of falling water to turn turbines (e.g., Akosombo Dam, Bui Dam, Kpong Dam). Thermal Power: Burning natural gas to heat water into steam, which turns turbines (e.g., Aboadze Thermal Plant, Karpower ships). Solar Power: Converting sunlight directly into electricity using solar panels (e.g., Navrongo Solar Power Station).
At the power station, huge generators produce electricity at a voltage that is high, but not high enough for long-distance travel (typically between 11 kV and 25 kV). Stage 2: Power Transmission (The Electrical Highway) This is the process of moving large amounts of electricity over long distances, for example, from the Akosombo Dam to major cities like Accra, Kumasi, or Takoradi. The company responsible for this in Ghana is the Ghana Grid Company (GRIDCo).
The Key Challenge: When electricity flows through a wire, some energy is lost as heat. This is called power loss or Joule heating. The formula for power loss is: Power Loss (P_loss) = I²R
Where: I is the current (in Amperes, A) R is the resistance of the wire (in Ohms, Ω)