characteristics of Types of Electrical Loads for JSS 1

Class: JSS 1
Term: First Term
Week: 4
Age: 12 years
Duration: 45 minutes
Subject: Solar PV Installation and Maintenance
Curriculum Theme: Solar Photovoltaics System for Electricity Generation
Focal competence: Demonstrate the knowledge of Solar Photovoltaics System and safety precautions
Key competencies/values: Communication; Collaboration; ICT and Digital Competencies
Skills:

• Using name plates of appliances, functions or power source to determine their category of load

Previous Lesson: Meaning of Electrical loads
Topic: Electrical Appliances Power Load/Loads Sizing: Characteristics Of Types Of Electrical Loads
Subject Matter: characteristics of Types of Electrical Loads

Specific Objectives

By the end of the lesson, pupils/students should be able to:

Cognitive Domain

• Explain what electrical loads are.
• Identify the different types of electrical loads.
• Describe the characteristics of resistive electrical loads.
• Describe the characteristics of inductive electrical loads.
• Describe the characteristics of capacitive electrical loads.

Psychomotor Domain

• Categorize common electrical appliances into their respective load types using their functions or nameplates.

Reference Materials

The following resources were used in planning this lesson:

• 2025 Revised 9 Years Basic Education Curriculum
• Relevant State Unified Scheme of Work
• Basic Electricity and Electronics for Junior Secondary Schools, Book 1
• The HeadTeacher Scheme of work

Instructional Materials

The teacher will teach this lesson with the aid of:

• Approved curriculum resource/material
• Chart showing different electrical appliances and their load types
• Examples of electrical appliances such as an incandescent bulb, electric fan, fluorescent lamp, refrigerator, and a capacitor.
• Nameplates of various electrical appliances

Rationale for the Lesson

Understanding the characteristics of different electrical loads is essential for students to grasp how solar PV systems interact with appliances. This knowledge helps in correctly sizing solar systems, ensuring efficient energy usage, and preventing damage to components. It also provides a practical foundation for future careers in renewable energy installation and maintenance.

Prerequisite/Previous Knowledge

Students should have basic knowledge of electricity, simple electrical circuits, and common household electrical appliances.

Lesson Content/Board Summary

Electrical Appliances Power Load/Loads Sizing: Characteristics Of Types Of Electrical Loads

What are Electrical Loads?

An electrical load is any component or device that consumes electrical energy and converts it into another form of energy (e.g., light, heat, motion). In a solar PV system, loads are the appliances connected to the system that draw power from it.

Types of Electrical Loads and Their Characteristics

Electrical loads are generally classified into three main types based on how they interact with the alternating current (AC) power supply. These types are resistive, inductive, and capacitive loads.

1. Resistive Loads

Resistive loads are devices that convert electrical energy directly into heat or light. They do not store energy in magnetic or electric fields.

Characteristics of Resistive Loads:

1. They offer resistance to the flow of current.
2. The current and voltage waveforms are in phase, meaning they rise and fall at the same time.
3. They consume real power (active power) and have a power factor close to 1.
4. They do not cause any phase shift between voltage and current.
5. They are generally easy to size and manage in electrical systems.

Examples of Resistive Loads:

1. Incandescent light bulbs
2. Electric heaters
3. Toasters
4. Electric kettles
5. Ovens
6. Irons

2. Inductive Loads

Inductive loads are devices that use magnetic fields to operate. They typically contain coils of wire, which create an electromagnetic field when current flows through them.

Characteristics of Inductive Loads:

1. They cause the current waveform to lag behind the voltage waveform (current lags voltage).
2. They consume both real power and reactive power.
3. They have a power factor less than 1, typically lagging.
4. They draw a large surge of current (inrush current) when first switched on.
5. They can cause voltage drops and require careful sizing in a solar PV system.

Examples of Inductive Loads:

1. Electric motors (found in fans, refrigerators, washing machines, pumps)
2. Transformers
3. Fluorescent lamp ballasts
4. Air conditioners
5. Vacuum cleaners

3. Capacitive Loads

Capacitive loads are devices that store electrical energy in an electric field. They typically contain capacitors.

Characteristics of Capacitive Loads:

1. They cause the current waveform to lead the voltage waveform (current leads voltage).
2. They also consume both real power and reactive power.
3. They have a power factor less than 1, typically leading.
4. They can also draw a high initial current when first connected.
5. They are less common as primary loads in typical household solar PV systems compared to resistive and inductive loads, but they exist.

Examples of Capacitive Loads:

1. Capacitors (used in motor starting, power factor correction)
2. Some types of electronic equipment (e.g., power supplies, LED drivers)
3. Long transmission cables (though not typically a “load” in the appliance sense for JSS 1)

Teaching Methods/Instructional Techniques

Discussion, Demonstration, Guided Practice, Question and Answer, Explanation, Observation, Practical Activity.

Instructional Procedures

Step 1: Introduction

Time: 5 minutes

Teaching Skill: Engaging/Questioning

Teacher’s Activity: The teacher greets the students and reviews the previous lesson briefly. The teacher then asks students to name some electrical appliances they use daily and how they consume electricity.

Pupils’ Activity: Students respond to the teacher’s questions and name various electrical appliances.

Learning Point: Recalling electrical appliances

Step 2: Explanation of Electrical Loads

Time: 7 minutes

Teaching Skill: Explanation/Definition

Teacher’s Activity: The teacher explains what an electrical load is, emphasizing that it is anything that uses electrical energy. The teacher introduces the three main types of electrical loads: resistive, inductive, and capacitive.

Pupils’ Activity: Students listen attentively and ask questions for clarity.

Learning Point: Meaning of electrical loads

Step 3: Identification of Resistive Loads

Time: 7 minutes

Teaching Skill: Demonstration/Observation

Teacher’s Activity: The teacher displays examples of resistive loads (e.g., incandescent bulb, electric heater) and explains their characteristics, such as converting electricity to heat/light directly and having current/voltage in phase. The teacher guides students to identify these characteristics.

Pupils’ Activity: Students observe the appliances, listen to the explanation, and identify the characteristics of resistive loads.

Learning Point: Resistive load characteristics

Step 4: Identification of Inductive Loads

Time: 7 minutes

Teaching Skill: Demonstration/Explanation

Teacher’s Activity: The teacher displays examples of inductive loads (e.g., electric fan, small motor, refrigerator nameplate) and explains their characteristics, such as using magnetic fields, current lagging voltage, and high starting current. The teacher guides students to identify these characteristics.

Pupils’ Activity: Students observe the appliances/nameplates, listen to the explanation, and identify the characteristics of inductive loads.

Learning Point: Inductive load characteristics

Step 5: Identification of Capacitive Loads

Time: 7 minutes

Teaching Skill: Explanation/Discussion

Teacher’s Activity: The teacher explains capacitive loads, showing a capacitor if available, and describes their characteristics, such as storing energy in electric fields and current leading voltage. The teacher discusses examples where they are found.

Pupils’ Activity: Students listen, observe, and discuss the characteristics and examples of capacitive loads.

Learning Point: Capacitive load characteristics

Step 6: Characteristics of Types of Electrical Loads

Time: 3 minutes

Teaching Skill: Summarization/Reinforcement

Teacher’s Activity: The teacher leads a brief recap, asking students to state the key characteristics that differentiate the three types of loads, using the chart if available.

Pupils’ Activity: Students actively participate in the recap, stating the characteristics of each load type.

Learning Point: Differentiating load characteristics

Step 7: Evaluation/Review

Time: 5 minutes

Teaching Skill: Questioning/Assessment

Teacher’s Activity: The teacher evaluates the learning by asking the following questions:

1. What is an electrical load?
2. Name the three main types of electrical loads.
3. Give two examples of a resistive load.
4. Describe one characteristic of an inductive load.
5. How is a capacitive load different from an inductive load in terms of current and voltage phase?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Understanding electrical loads

Step 8: Note-Taking

Time: 4 minutes

Teaching Skill: Guided Writing

Teacher’s Activity: The teacher guides pupils/students to copy the essential Board Summary notes on electrical loads and their characteristics into their notebooks.

Pupils’ Activity: Pupils/students copy the notes carefully into their notebooks.

Learning Point: Recording lesson content

Step 9: Conclusion

Time: 3 minutes

Teaching Skill: Consolidation

Teacher’s Activity: The teacher summarizes the lesson by reiterating the importance of understanding different load types for solar PV system design and encourages students to observe appliances at home to identify their load types. The teacher then dismisses the class.

Pupils’ Activity: Students listen to the summary and prepare for dismissal.

Learning Point: Reinforcing lesson importance

Continuous Assessment/Further Study

Type: Homework

Instruction: Observe electrical appliances in your home or school and identify their load types. For each appliance, write down its name and state whether it is primarily a resistive, inductive, or capacitive load. Explain your reasoning for at least two appliances.

1. List five resistive loads found in your home.
2. List five inductive loads found in your home.
3. Choose one appliance and explain how you determined its load type.

Lesson Keywords

• Electrical Load – A device or component that consumes electrical energy.
• Resistive Load – Converts electrical energy directly to heat or light; current and voltage are in phase.
• Inductive Load – Uses magnetic fields to operate; current lags voltage.
• Capacitive Load – Stores energy in an electric field; current leads voltage.
• Power Factor – A measure of how effectively electrical power is being used.

Differentiation

For weaker learners, focus on identifying common resistive and inductive loads through direct observation and simple examples. Provide a simplified chart for reference. For faster learners, challenge them to research the concept of “power factor” in relation to different load types and its impact on a solar PV system’s efficiency.

Suggested Lesson Videos

For further understanding of electrical loads, search on YouTube for: types of electrical loads for solar pv jss1

Teacher Guide for Using This Lesson Plan

Before the lesson, gather actual examples of resistive (e.g., incandescent bulb), inductive (e.g., small fan, toy motor), and if possible, a large capacitor or an appliance nameplate showing power factor. Start by connecting to students’ everyday experiences with appliances. When explaining each load type, use the physical examples or nameplates to make the concept concrete. Emphasize the unique characteristics of each load type, especially the phase relationship between current and voltage for inductive and capacitive loads, though keep the explanation simple for JSS 1. Encourage students to ask questions and engage in discussions. During Step 7 (Evaluation), ensure questions cover all three load types and their basic characteristics. Students should copy the Board Summary notes in Step 8 to reinforce learning. Provide clear instructions for the homework assignment to encourage practical application of the knowledge.