Lesson Notes By Weeks and Term v4 - SHS 3

Lesson Video

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Performance objectives

• Classify appliances as resistive or inductive loads.
• Describe common electrical faults.
• Explain how these faults affect appliances.
• Identify examples in your home.

Lesson summary

In our homes in Ghana, from Accra to Bolgatanga, we use electrical appliances every single day. We use them to cook our banku, press our school uniforms, keep our food fresh, and cool ourselves down. However, not all appliances work the same way. Understanding the *type* of electrical load an appliance presents and the common problems (faults) that can occur is crucial for safety, saving money on ECG bills, and basic troubleshooting. This lesson will empower you to be a smarter and safer user of electricity in your home and community.

Lesson notes

Part 1: Classification of Electrical Loads

An electrical load is any component or device in a circuit that consumes electrical energy and converts it into another form of energy, such as heat, light, or motion. In our homes, appliances are loads. We can classify them into two main categories: Resistive and Inductive.

A. Resistive Loads Definition: A resistive load is an electrical load that works by resisting the flow of electric current. This resistance directly converts electrical energy into thermal energy (heat) or light. How they work: Think of it like friction. As electrons are forced through a material that resists their flow (like the heating element in a kettle), they collide with atoms, creating vibration and heat. In resistive loads, the voltage and current are "in phase," meaning they rise and fall at the same time. Key Characteristics: They primarily produce heat or light. They have a high power factor (close to 1.0), meaning they use electricity very efficiently. They present a steady and constant demand for current once switched on. Common Ghanaian Examples: Electric Pressing Iron: The flat base gets hot due to a resistive heating element inside. Electric Kettle: The coil at the bottom that boils the water is a resistive element. Water Heater (Geyser): Works just like a large kettle to heat water for bathing. Electric Cooker / Hot Plate: The red-glowing coils are classic resistive loads. Incandescent Light Bulbs: The old-fashioned bulbs with the glowing filament.

B. Inductive Loads Definition: An inductive load is an electrical load that uses a magnetic field to produce motion. These loads typically contain a motor, which consists of coils of wire. How they work: When current flows through a coil of wire, it creates a magnetic field. By carefully controlling these magnetic fields, we can make a shaft rotate, which is the basis of all electric motors. In inductive loads, the current "lags" behind the voltage because it takes time and energy to build up the magnetic field. Key Characteristics: They contain coils, windings, or motors. They primarily produce motion. They require a large surge of current to start up (known as "inrush current"). This is why your lights might dim for a split second when a fridge or A/C turns on. They have a lower power factor (less than 1.0), which means they are less efficient in their use of electricity from the grid. Common Ghanaian Examples: Ceiling Fan / Standing Fan: The motor spins the blades. Blender: The motor spins the blades to chop food. Refrigerator / Freezer: A compressor motor (inductive load) pumps refrigerant to cool the inside. Air Conditioner (A/C): Contains both a fan motor and a compressor motor. Washing Machine: A motor spins the drum. Water Pump ("Pumping Machine"): A motor drives an impeller to pump water into your Polytank. Part 2: Common Electrical Faults

Evaluation guide

• Classify home appliances under resistive and inductive loads and outline faults
• associated with them
• Focal Area: classification of elelctrical appliances and common faults associated with
• them