# 1. Principles of Electrical Engineering 1.1 Fundamentals of Electronics ### Fundamentals of Electronics

The purpose of this section is to briefly touch upon fundamentals of electronics that will be discussed in the report.

1.1.1

Current

Current consists of the flow of very large numbers of charged particles through a conductor. These charged particles are electrons and protons which are commonly referred to as elementary charges. Electric current is defined as the time rate of change of charge passing through a predetermined area 4 . Electric current is measured in amperes or amps

(A).

1.1.2

Voltage

A voltage, or potential difference, between two points in a circuit indicates the energy required to move charge from one point to another

4

. The voltage is a measure of the driving force for the flow of current through a circuit or conductor. This potential difference is measured in a unit called Volt (V).

1.1.3

Resistance

When electric current flows through a conductor it encounters a certain amount of resistance. Resistance is the opposition to current that is provided by the conductor

5

.

This resistance is measures in a unit called ohms ( Ω ).

1.1.4

Direct Current

Direct current (DC) is the flow of charge in one direction through a conductor. As shown

in Figure 1, the current flows in one direction through the circuit and is constant in

magnitude and direction.

1

Figure 1 – Direct Current 5

1.1.5

Alternating Current

Alternating current (AC) is bi-directional, meaning that the flow of charge changes direction periodically

5

. As shown in Figure 2, the magnitude and direction of the current

are not constant. From period t

0

to t

1

the current is positive and the flow in the circuit is clockwise. From period t

1

to t

2

the current is negative and the flow in the circuit is counter-clockwise.

Figure 2 – Alternating Current 5

1.1.5.1

Three Phase AC Power

Three phase power is produced when three sinusoidal voltages that are shown in Ошибка! Источник ссылки не найден.

are generated 120 o out of phase with one another.

Advantages of three phase over single phase power include increased efficiency and constant supply of power.

2

1.1.5.2

Three Phase Power Delta and WYE Connections

Three phase delta and WYE connections are two different arrangements where AC

sources are connected. Figure 3 shows a delta configuration on the left and a WYE

configuration on the right.

Figure 3 – Delta and WYE Configurations 4

### Fundamentals of Circuitry

1.2.1

Energy Storage in Circuits

Capacitance and Inductance are two methods for energy storage in a circuit. Both these methods store energy in an electromagnetic field. Two electrical components that can induce capacitance and inductance in a circuit are called capacitors and inductors, respectively.

1.2.1.1

Capacitors

The most basic type of capacitor is constructed with two parallel plates and is separated

by an insulating material, as shown in Figure 4. In a DC circuit a capacitor acts as an

open in the circuit.

3

Figure 4 – Capacitor Construction 5

1.2.2

Inductors

1.2.3

Grounding

1.2.4

Shorting

1.3.1

Wire Shielding

1.3.2

Isolated Wires

1.4.1

Signal Noise

Wires

Connected

Ground

Symbols

Coaxial

Cable or

Shielded

Line

Shielded

Conductor

Shielded Multi-

Conductor

Cable

XXXXXXX

6

4

5