# Electrical Theory for Troubleshooters

## iKNOW

This library consists of 12 interactive, on-line lessons. These lessons are excellent for the training of electricians and electronic technicians as well as for the multi-craft training needs of process and manufacturing facilities. The first four lessons in this library cover basic electrical concepts including Ohm’s Law and Kirchhoff’s Law, as well as the use of these laws to determine voltage, current, and resistance in series and parallel circuits.

- 1. Introduction to Electricity
- 2. Basic Electrical Properties
- 3. Series Circuits
- 4. Parallel Circuits
- 5. Alternating Current
- 6. Electromagnetism
- 7. Inductance
- 8. Capacitance
- 9. Three-Phase Circuits
- 10. Wye and Delta Connections
- 11. Introduction to Transformers
- 12. Transformers

### Introduction to Electricity

**Description:** This is the first lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson uses animation to demonstrate atomic structure, electricity, and how a simple circuit operates. The lesson also explains the characteristics of good conductors and insulators.

**Prerequisites:** None

**Topics:**

Atomic Structure

What is Electricity?

Conductors and Insulators

Circuits

**Objectives:**

- Describe the atomic structure of matter
- Describe the characteristics of good conductors and insulators
- Define electricity
- Describe how a simple circuit operates

### Basic Electrical Properties

**Description:** This is the second lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson covers Ohm’s Law, as well as the use of Ohm’s Law to calculate an unknown value. The lesson also defines voltage, current, resistance, and power.

**Prerequisites:** Completion of the lesson, Introduction to Electricity, is recommended.

**Topics:**

Voltage

Current

Resistance

Ohm’s Law

Power

**Objectives:**

- Define voltage
- Define current
- Define resistance
- Describe voltage and current relationships
- State Ohm’s Law
- Use Ohm’s Law to calculate an unknown value
- Define power and how to use power values with Ohm’s Law

### Series Circuits

**Description: **This is the third lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. The lesson presents the operation of a series circuit and trains participants in the identification of simple schematic symbols used to represent components in a series circuit. The behavior of current, resistance, and current in a series circuit, and the used of Kirchhoff’s Voltage Law to find total voltage are also covered.

**Prerequisites: **Basic understanding of electrical circuits and a solid understanding of Ohm’s law is recommended.

**Topics:**

Series Circuit Operation

Schematic Symbols

Series Resistance

Voltage Drop

Kirchhoff’s Law

Troubleshooting

**Objectives:**

- Define a series circuit
- Properly identify simple schematic symbols for a battery, switch, lamp, resistor, and conductor
- Describe how current and resistance behave in a series circuit
- Describe how voltage behaves in a series circuit
- Use Kirchhoff’s Voltage Law to find total voltage in a series circuit

### Parallel Circuits

**Description: **This is the fourth lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson describes the behavior of voltage, current, and resistance in a parallel circuit. The learner is also instructed in the identification of the series and parallel portions of a series-parallel circuit.

**Prerequisites:** Understanding Ohm’s Law, Kirchhoff’s Law, and series circuits is recommended.

**Topics:**

Voltage in Parallel Circuits

Current in Parallel Circuits

Resistance in Parallel Circuits

Series – Parallel Circuits

**Objectives:**

- Describe how voltage and current behave in a parallel circuit
- Describe how resistance behaves in a parallel circuit
- Identify the series portions of a series-parallel circuit
- Identify the parallel portions of a series-parallel circuit
- Simplify a series-parallel circuit to determine how voltage, current and resistance behave

### Alternating Current

**Description:** This is the fifth lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson teaches the basic AC characteristics of voltage, including how voltage changes over time. The participant is also instructed in using sine waves to interpret the frequency of AC voltage.

**Prerequisites: **This lesson was designed for participants familiar with Ohm’s Law.

**Topics:**

Overview

Polarity and Magnitude

Sine Wave

Frequency

Troubleshooting

**Objectives:**

- State the basic operating AC Characteristics of voltage
- Explain how AC voltage changes over time
- Define sine wave and cycle
- Interpret the frequency of AC voltage using a sine wave
- Explain RMS voltage vs. peak voltage

### Electromagnetism

**Description:** This sixth lesson in the iKNOW™ Electrical Theory for Troubleshooters Library uses animations and demonstrations to explain the principles of magnetism, including flux density and electromagnetic induction. The lesson also shows how to plot a sine wave using a graph.

**Prerequisites:** This lesson was designed for participants familiar with AC characteristics.

**Topics:**

Understanding Magnetism

Principles of Magnetism

Flux Density

Electromagnetic Induction

Induced Voltage Sine Wave

**Objectives:**

- Describe the principles of magnetism
- Describe flux and flux density
- Describe how electromagnetic induction takes place
- Describe how a magnetic field is generated by passing current through a conductor
- Plot a sine wave using a graph

### Inductance

**Description:** This is the seventh lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson builds on the information presented in the lesson, Electromagnetism. Types of induction, phase, and the effect of induction in AC circuits are covered.

**Prerequisites:** This lesson was designed for participants familiar with alternating current and electromagnetism.

**Topics:**

Current Flow

Self-Inductance & Mutual Induction

Coils – Mutual Induction

Transformer Induction

Transformer Taps

Effect of Inductance & Phase Relationships

**Objectives:**

- Describe how a magnetic field is generated by passing current through a conductor
- Explain self-induction
- Explain counter-electromagnetic field
- Describe how current is induced in a coil-type conductor
- Explain mutual induction
- Explain the principle of transformer function
- Explain the function of a tap in transformer construction
- Describe the effect of inductance in AC circuits

### Capacitance

**Description:** This is the eighth lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson explains capacitors, their function, and how capacitance affects AC circuits.

**Prerequisites:** This lesson was designed for participants familiar with alternating current, electro-magnetism, and induction.

**Topics:**

Capacitor Defined

Charging a Capacitor

Discharging a Capacitor

Effects of Capacitance

**Objectives:**

- Define capacitance and identify its schematic symbol
- Explain how a capacitor becomes charged
- Explain how a capacitor becomes discharged
- Explain how capacitance affects AC circuits

### Three-Phase Circuits

**Description:** This is the ninth lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson defines 3-phase AC, describes the components and operating principle of 3-phase generators, and using the formula for frequency, shows how rotor speed and the number of poles is related to frequency.

**Prerequisites:** The lesson requires a fundamental knowledge of electrical theory and technology.

**Topics:**

Definition of 3-Phase

3-Phase Generators

3-Phase Sine Wave

Frequency

**Objectives:**

- Define 3-phase AC
- Differentiate between 3-phase and 1-phase AC
- Describe the components and operating principle of a 3-phase generator
- Use a sine wave to show how 3-phase voltage changes over time
- Explain the relationship between frequency and rotor speed
- State and apply the formula for frequency
- Describe how rotor speed and the number of poles related to frequency

### Wye and Delta Connections

**Description:** The tenth lesson in the iKNOW™ Electrical Theory for Troubleshooters Library, this lesson discusses Wye and Delta configurations and explains the relationship between phase and line voltages in various connections, and demonstrates the application of the formula that shows this relationship.

**Prerequisites:** The lesson requires a fundamental knowledge of electrical theory and technology. Basic knowledge of 3-phase circuits is recommended.

**Topics:**

3-Wire Wye Configuration

4-Wire Wye Configuration

Delta Configuration

Real and Apparent Power

**Objectives:**

- Describe the relationship between phase and line voltages in a 3-wire wye connection
- Describe the relationship between phase and line voltages in a 4-wire wye connection
- Describe the relationship between phase and line currents in a delta connection
- Calculate power in a 3-phase load
- Apply the formula that shows the relationship between phase and line currents in a 3-wire wye connection
- Apply the formula that shows the relationship between phase voltage and single-phase load voltage in a 4-wire wye connection
- Describe the the relationship between phase and line voltages in a delta connection

### Introduction to Transformers

**Description: **The eleventh lesson in the iKNOW™ Electrical Theory for Troubleshooters Library, this lesson presents the basic parts of a transformer and their function. The lesson explains turns ratio and its relationship to a transformer’s input and output voltages. The participant is also cautioned regarding the dangers of improper transformer connections.

**Prerequisites:** The lesson requires a fundamental knowledge of electrical theory and technology.

**Topics:**

Transformer Parts

Turns Ratio

Avoiding Improper Connections

**Objectives:**

- Identify and describe the functions of the basic transformer parts
- Explain the relationship between a transformer’s turns ratio and its input and output voltages
- Describe the danger in reversing or stepping-up the voltage

### Transformers

**Description: **This is the final lesson in the iKNOW™ Electrical Theory for Troubleshooters Library. This lesson builds on the information presented in the lesson, Introduction to Transformers. How to determine primary current and voltage, secondary current and voltage, and load is taught. The function of various transformers is also explained.

**Prerequisites:** The lesson requires a fundamental knowledge of electrical theory and technology. Completion of the lesson, Introduction to Transformers, is required.

**Topics:**

Determining Secondary Current

Determining Power

Determining Primary Current

3 Phase Transformers

Multi-tap and Autotransformers

**Objectives:**

- Given the secondary voltage and load, determine the primary current
- Given the primary voltage and load, determine the secondary current
- Given the turns ratio and voltage and current from either the primary or secondary, determine the power
- Given power and primary voltage, determine primary current
- Given primary voltage, determine secondary voltage in a 3-phase transformer
- Describe the configuration of a 3-phase transformer
- State some applications and maintenance precautions for a 3-phase transformer
- Explain the functions and uses of multi-tap transformer and autotransformers