Winding Drawings, Wave and Lap Windings for SS 3

Class: SS 3
Term: First Term
Week: 8
Age: 16 years
Duration: 45 minutes
Subject: Electrical Installation and Maintenance Work
Topic: WINDING DRAWING
Subject Matter: Draw and interpret simple wave and Lap; Application of wave; Determination of coil
Previous Lesson: Machine Installation and Types of Enclosures

Specific Objectives

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

Cognitive Domain

• Define wave and lap windings.
• Explain the key differences between wave and lap windings.
• State the applications of wave windings.

Psychomotor Domain

• Draw simple diagrams of wave windings.
• Draw simple diagrams of lap windings.
• Interpret given diagrams of wave and lap windings.
• Identify the position of coil ends in winding diagrams.

Affective Domain

• Appreciate the importance of accurate winding drawings in electrical machine construction.
• Recognise the need for precision in electrical installation work.

Reference Materials

The following resources were used in planning this lesson:

• 2025 Revised 9 Years Basic Education Curriculum
• Relevant State Unified Scheme of Work
• Electrical Installation and Maintenance Work for Senior Secondary Schools, Book 3
• The HeadTeacher Scheme of work

Instructional Materials

The teacher will teach this lesson with the aid of:

• Diagrams of simple wave and lap windings (on chart or projector)
• Drawing instruments (rulers, pencils, protractors)
• Copper coil (for demonstration of coil ends)
• Starter (for demonstration, if available)
• Whiteboard or chalkboard

Rationale for the Lesson

This lesson is essential for students to grasp the fundamental principles behind the construction and operation of DC machines. Understanding winding drawings helps in troubleshooting, maintenance, and the design of electrical equipment. It provides a practical foundation for future studies and careers in electrical engineering and installation.

Prerequisite/Previous Knowledge

Students should have basic knowledge of electrical circuits, conductors, insulators, and the components of simple DC machines from previous lessons.

Lesson Content/Board Summary

WINDING DRAWING

Introduction to Armature Windings

Armature windings are the coils of wire placed in the slots of an armature core, which are responsible for generating or receiving voltage in a DC machine. There are two main types of armature windings: lap winding and wave winding.

Lap Winding

Lap winding is a type of armature winding where the ends of each coil are connected to adjacent commutator segments. This results in the winding “lapping back” on itself.

1. Characteristics:

• It has parallel paths equal to the number of poles (P).
• It is suitable for high-current, low-voltage machines.
• The coil sides are connected to adjacent commutator segments.

To draw a simple lap winding, consider the armature slots and commutator segments. Each coil spans across a certain number of slots (coil span). The end of one coil connects to a commutator segment, and the start of the next coil connects to the adjacent segment, creating parallel paths.

Wave Winding

Wave winding is a type of armature winding where the ends of each coil are connected to commutator segments that are separated by a certain distance, causing the winding to progress in a “wave-like” manner around the armature.

1. Characteristics:

• It has only two parallel paths, regardless of the number of poles.
• It is suitable for low-current, high-voltage machines.
• The coil sides are connected to commutator segments that are not adjacent.

To draw a simple wave winding, observe that the winding forms a continuous path, progressing around the armature. The end of one coil connects to a commutator segment, and the start of the next coil connects to a segment further away, creating a series connection of coils.

Application of Wave Windings

Wave windings are primarily used in DC machines that require:

1. High voltage output.
2. Low current output.
3. Fewer brushes (due to having only two parallel paths).
4. Examples include small DC generators and motors where high voltage is preferred over high current.

Determination of Coil Ends and Position

The determination of coil ends and their position is crucial for correct winding connections. Each coil has two ends: a start end and a finish end.

1. Start End: The beginning of the coil.
2. Finish End: The end of the coil.
3. Position: The position refers to which commutator segment or other coil end a particular coil end connects to. In lap windings, coil ends connect to adjacent segments. In wave windings, coil ends connect to segments separated by a pole pitch, ensuring a continuous series path.
4. Observation: Careful observation of the winding diagram is necessary to trace the path of the current and identify the start and finish of each coil within the overall winding pattern.

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: Activating Prior Knowledge

Teacher’s Activity: The teacher greets the students and reviews previous knowledge about the basic components of a DC machine, asking students to name parts like the armature, commutator, and field poles. The teacher then introduces the topic of armature windings as a key part of the armature.

Pupils’ Activity: Students respond to questions about DC machine components and listen attentively to the introduction.

Learning Point: Armature winding importance

Step 2: Introduction to Lap Winding

Time: 8 minutes

Teaching Skill: Explanation/Demonstration

Teacher’s Activity: The teacher explains what lap winding is, its characteristics (high current, low voltage, parallel paths = poles), and shows a prepared diagram of a simple lap winding. The teacher demonstrates how coil ends connect to adjacent commutator segments using the diagram and a copper coil model.

Pupils’ Activity: Students observe the diagrams and models, ask questions, and take initial notes.

Learning Point: Lap winding characteristics

Step 3: Drawing Lap Winding

Time: 7 minutes

Teaching Skill: Guided Practice

Teacher’s Activity: The teacher guides students to draw a simple lap winding diagram on their notebooks, providing step-by-step instructions on drawing slots, coils, and commutator connections. The teacher moves around to assist students.

Pupils’ Activity: Students attempt to draw a simple lap winding diagram in their notebooks under teacher guidance.

Learning Point: Lap winding drawing

Step 4: Introduction to Wave Winding

Time: 8 minutes

Teaching Skill: Explanation/Demonstration

Teacher’s Activity: The teacher explains what wave winding is, its characteristics (low current, high voltage, two parallel paths), and shows a prepared diagram of a simple wave winding. The teacher demonstrates how coil ends connect to non-adjacent commutator segments using the diagram and a copper coil model.

Pupils’ Activity: Students observe the diagrams and models, identify differences from lap winding, and ask questions.

Learning Point: Wave winding characteristics

Step 5: Drawing Wave Winding and Coil End Determination

Time: 7 minutes

Teaching Skill: Guided Practice/Observation

Teacher’s Activity: The teacher guides students to draw a simple wave winding diagram. The teacher also highlights how to observe and determine the start and finish ends of coils within both lap and wave winding diagrams.

Pupils’ Activity: Students draw the wave winding and practice identifying coil ends in both winding types.

Learning Point: Wave winding drawing

Step 6: Application of Wave Windings

Time: 3 minutes

Teaching Skill: Explanation

Teacher’s Activity: The teacher explains the practical applications of wave windings, focusing on their suitability for high-voltage, low-current machines and the benefits of fewer brushes.

Pupils’ Activity: Students listen and note down the applications of wave windings.

Learning Point: Wave winding applications

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 the main difference between lap and wave windings in terms of parallel paths?
2. Draw a simple diagram of a lap winding.
3. State two applications of wave windings.
4. How do you determine the position of coil ends in a winding diagram?

Pupils’ Activity: Pupils answer orally and in writing.

Learning Point: Winding types understanding

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 lap and wave windings, their characteristics, applications, and coil end determination into their notebooks.

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

Learning Point: Winding notes recording

Step 9: Conclusion

Time: 2 minutes

Teaching Skill: Consolidation

Teacher’s Activity: The teacher briefly summarises the main points of the lesson, reiterating the importance of understanding winding drawings for electrical machine construction and maintenance. The teacher encourages students to continue practicing drawing the windings.

Pupils’ Activity: Students listen and prepare for the next lesson.

Learning Point: Winding drawing consolidated

Continuous Assessment/Further Study

Type: Homework

Instruction: Answer the following questions in your notebook.

1. Explain the principle behind lap winding and state one advantage.
2. Explain the principle behind wave winding and state one advantage.
3. Draw a simple diagram illustrating the connection of coil ends in a wave winding.
4. Research and list two specific types of DC machines that typically use lap windings.
5. Research and list two specific types of DC machines that typically use wave windings.

Lesson Keywords

• Armature Winding – Coils of wire in an armature core.
• Lap Winding – Winding where coil ends connect to adjacent commutator segments.
• Wave Winding – Winding where coil ends connect to non-adjacent commutator segments, forming a continuous path.
• Commutator Segment – Copper bars forming a ring, connected to armature coils.
• Coil End – The start or finish point of an individual coil.

Differentiation

For weaker learners, provide pre-drawn templates of armature slots and commutator segments to simplify the drawing task. Focus on identifying the basic connection patterns. For faster learners, challenge them to draw windings with a specified number of poles and slots, or ask them to research the concept of “coil span” and “pitch” in windings.

Suggested Lesson Videos

For further understanding, students can search YouTube for:
lap and wave winding electrical machines SS3

Teacher Guide for Using This Lesson Plan

Before the lesson, prepare clear, large diagrams of both lap and wave windings. Having a simple copper coil or wire model can greatly aid in demonstrating coil ends and connections. Ensure students have their drawing instruments ready. Begin by reviewing the basics of DC machine components to set the context. When demonstrating drawing, go step-by-step, allowing students to follow along. Emphasise the visual differences in how coil ends connect for lap versus wave windings. During the guided practice, circulate to provide individual assistance and correct misconceptions. For the note-taking phase, ensure the board summary is clear and concise for students to copy accurately. Encourage questions throughout the lesson to check understanding.