Lesson Notes By Weeks and Term v5 - Grade 12
Preparation for practical assessment tasks – Week 6 focus
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Preparation for practical assessment tasks – Week 6 focus
Download the Lessonotes Mobile South Africa app for faster lesson access on Android and iPhone.
Subject: Electrical Technology
Class: Grade 12
Term: 3rd Term
Week: 6
Theme: General lesson support
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This week is crucial as we focus intensely on preparing for your upcoming practical assessments. Electrical Technology isn't just about theory; it's about applying that knowledge practically to build, troubleshoot, and maintain electrical systems. These skills are directly applicable to addressing South Africa's infrastructure needs, from ensuring reliable power supply to homes and businesses to contributing to the growth of renewable energy sectors. This week's focus is designed to solidify your understanding and build your confidence in performing essential practical tasks accurately and safely.
This week's preparation centres on practical skills that directly translate into your ability to perform well in the assessment.
We'll focus on three critical areas: Transformers, Fault Finding & Appliance Repair, and Three-Phase Motor Star-Delta Starting. 2.1 Transformers: A transformer is a static device that transfers electrical energy from one circuit to another through electromagnetic induction. It consists of two or more coils electrically isolated but magnetically linked. The primary coil is connected to the input voltage, and the secondary coil is connected to the load. The key principle is Faraday's Law of Electromagnetic Induction.
Turns Ratio (N): The ratio of the number of turns in the primary coil (Np) to the number of turns in the secondary coil (Ns): N = Np / Ns Voltage Ratio (V): The ratio of the primary voltage (Vp) to the secondary voltage (Vs): V = Vp / Vs Ideally, V ≈
N. Current Ratio (I): The ratio of the primary current (Ip) to the secondary current (Is): I = Is / Ip. Ideally, I is the inverse of
N. Step-Up Transformer: N Vp) - Increases voltage, decreases current.
Step-Down Transformer: N > 1 (Vs < Vp) - Decreases voltage, increases current.