Principles of Electrical Science

Aim: The aim of this unit is to enable the candidate to understand the principles of electrical science related to AC theory, machines, devices and systems. This understanding is applied when designing wiring systems for clients and fault diagnosis.

Learning outcome

1 Understand electrical supply systems

1. describe how electricity is generated and transmitted for domestic and industrial/commercial consumption

2. specify the features and characteristics of a generation and transmission system

3. state the basic operating principles of other sources of electricity

4. describe the main characteristics of:

a. single phase electrical supplies

b. three phase electrical supplies

c. three phase and neutral supplies

d. sub-station transformers.

5. identify types of transformers

6. describe the operating principles, applications and limitations of transformers

7. determine by calculation and measurement:

a. primary and secondary voltages

b. primary and secondary current

c. kVA rating of a transformer.

2 Understand how different electrical properties can affect electrical circuits, systems and equipment

1. explain the relationship between resistance, inductance, capacitance and impedance

2. determine electrical quantities in alternating current circuits

3. explain the relationship between kW, kVAr, kVA and power factor

4. calculate power factor

5. explain what is meant by power factor correction

6. specify methods of power factor correction

7. determine the neutral current in a three-phase and neutral supply and why systems should be balanced

8. calculate values of voltage and current in star and delta connected systems

3 Understand the operating principles and applications of DC machines and AC motors

1. state the basic types, applications and describe the operating principles of DC machines

2. describe the operating principles of AC motors

3. state the basic types, applications and limitations of AC motors

4. describe the basic operating principles, limitations and applications of motor control

4 Understand the operating principles of electrical components

1. specify the main types and operating principles of electrical components

5. Understand the principles and applications of electrical lighting systems

1. explain the basic principles of illumination and state the applications of:

a. inverse square law

b. cosine law

c. lumen method.

2. explain the operating principles, types, limitations and applications of luminaires

6. Understand the principles and applications of electrical heating

1. explain the basic principles of electrical space heating and electrical water heating

2. explain the operating principles, types, limitations and applications of electrical space and water heating appliances and components