Basic Electricity - Senior Secondary 3 - Transformer and losses and transformer cooling

TERM: 1^ST TERM

WEEK THREE

Class: Senior Secondary School 3

Age: 17 years

Duration: 40 minutes of 5 periods each

Date:

Subject: BASIC ELECTRICITY

Topic: TRANSFORMER AND LOSSES AND TRANSFORMER COOLING

SPECIFIC OBJECTIVES: At the end of the lesson, pupils should be able to

I.) Define Transformer efficiency and losses

II.) Identify the methods of cooling a transformer

III.) State the applications of a transformer

INSTRUCTIONAL TECHNIQUES: Identification, explanation, questions and answers, demonstration, videos from source

INSTRUCTIONAL MATERIALS: Videos, loud speaker, textbook, pictures,

INSTRUCTIONAL PROCEDURES

PERIOD 1-2

NOTE

TRANSFORMER AND LOSSES AND TRANSFORMER COOLING

Transformer efficiency

Transformer efficiency is a measure of how effectively a transformer converts electrical power from the primary side to the secondary side while minimizing losses. It is defined as the ratio of output power (power delivered to the load) to input power (power supplied to the transformer). Mathematically, it is represented as:

Efficiency = (Output Power / Input Power) x 100%

Transformer losses

Transformer losses are the energy losses that occur during the conversion of electrical energy from the primary winding to the secondary winding. These losses reduce the overall efficiency of the transformer. There are two main types of losses:

1. Copper Losses (I²R Losses): Also known as ohmic losses, they occur due to the resistance of the transformer windings to the flow of current.
2. Iron or Core Losses: Also known as eddy current losses and hysteresis losses.

   - Eddy Current Losses: Occur due to the circulation of induced currents in the transformer's core. These currents create additional losses through resistive heating in the core material.

   - Hysteresis Losses: Occur due to the reversal of magnetization in the core material during each cycle of alternating magnetic field. This results in energy dissipation in the form of heat.

Methods of cooling a transformer

The cooling methods of a transformer are:

1. Air Cooling: In air-cooled transformers, natural convection or forced air circulation is used to dissipate heat from the transformer windings and core. This method is commonly used for smaller transformers and those operating at lower power levels.
2. Oil Cooling: Oil cooling involves immersing the transformer windings and core in an insulating oil with high dielectric strength and good thermal conductivity. The oil absorbs heat generated during operation and transfers it to the cooling surfaces (such as radiators or oil coolers) where it is dissipated into the surrounding environment.
3. Fan Cooling: Fan cooling is often used in conjunction with oil cooling to enhance heat dissipation.Fans are used to increase air circulation around the transformer, improving cooling efficiency.

Applications of transformers

A transformer has applications in the following areas:

1. Power Distribution: Transformers are used in power distribution systems to step up voltages for long-distance transmission and step down voltages for distribution to consumers.
2. Electrical Grids: Transformers play a crucial role in electrical grids, facilitating the efficient transmission and distribution of electricity across various voltage levels.
3. Industrial Applications: Transformers are used in industrial settings for powering machinery, equipment, and motors at different voltage levels.
4. Residential and Commercial Buildings: Transformers are used in buildings for providing power at suitable voltage levels for lighting, appliances, and other electrical loads.
5. Renewable Energy Systems: Transformers are used in renewable energy systems, such as wind farms and solar power plants, for stepping up voltages generated by the renewable sources before feeding them into the grid.

EVALUATION: 1. Differentiate between transformer efficiency and transformer losses

2. Give 3 examples of transformer losses
3. State 3 methods of cooling a transformer
4. Identify 4 applications of a transformer

CLASSWORK: As in evaluation

CONCLUSION: The teacher commends the students positively