Lesson Notes By Weeks and Term v4 - SHS 1
Energy Efficiency and Conservation
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Energy Efficiency and Conservation
Download the Lessonotes Mobile Ghana app for faster lesson access on Android and iPhone.
Subject: Engineering
Class: SHS 1
Term: 2nd Term
Week: 6
Grade code: 1.2.3.LI.4
Strand code: 2
Sub-strand code: 3
Content standard code: 1.2.3.CS.1
Indicator code: 1.2.3.LI.4
Theme: Ene rgy Systems
Subtheme: Energy Efficiency and Conservation
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In Ghana, we are all familiar with our electricity bills from the Electricity Company of Ghana (ECG) or the Northern Electricity Distribution Company (NEDCo). Sometimes, these bills are higher than we expect. We also experience power fluctuations and outages ("dumsor"). Understanding how much electricity each of our home and school appliances uses is the first step towards managing our consumption, saving money, and using our national energy resources wisely. This lesson will empower you to become an "energy detective" by teaching you how to read the information sticker on any appliance (its nameplate) and calculate exactly how much energy it consumes.
2.1 What is an Appliance Nameplate?
Think of a nameplate as the birth certificate or ID card of an electrical appliance. It is a label or plate, usually made of metal or a durable sticker, attached to the device by the manufacturer. It provides essential technical information about the appliance's operating requirements and performance.
Example of a simple nameplate (for a Standing Fan): > NASCO Standing Fan > Model: SF-1688 > Voltage: 220-240V > Frequency: 50Hz > Power: 60W 2.2 Key Parameters on a Nameplate
Let's break down the common terms you will find: Voltage (V): This is the electrical pressure the appliance needs to operate correctly. In Ghana, the standard mains voltage is 230V. Most appliances are rated for 220-240V to handle small fluctuations. *Unit:* Volts (V) Current (I): This is the flow of electric charge that the appliance draws from the power source when it's running. *Unit:* Amperes (A) or Amps Frequency (f or Hz): This describes how fast the direction of the alternating current (AC) changes. For Ghana and most of the world, this is 50 Hz. *Unit:* Hertz (Hz) Power (P): This is the rate at which the appliance consumes energy. It tells you how "powerful" the device is. A higher power rating means it uses energy faster. *Unit:* Watts (W) or Kilowatts (kW). (1000 W = 1 kW) Power Factor (PF or cos φ): This is a measure of how efficiently an AC appliance converts the current it draws into useful work. It is a number between 0 and 1. A purely resistive load, like a simple water heater or an incandescent bulb, has a PF of 1 (or 100% efficiency). Appliances with motors (fans, refrigerators, blenders) have a PF less than 1. For this level, think of it as an efficiency multiplier for calculating true power. 2.3 The Difference Between Power and Energy