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INEL 3105 – Electrical Systems Analysis I 2/19/2018

Basic Concepts 1

Objetivos del Curso
**Desarrollar el conocimiento, las destrezas y las técnicas
fundamentales para el análisis DC y AC de circuitos eléctricos
sencillos. Estudiar y analizar circuitos con elementos básicos,
tales como transformadores, amplificadores operacionales,
resistores, inductores y capacitores, utilizando las leyes de
Kirchhoff y los teoremas de simplificación eléctrica de Thevenin y
Norton.**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

2

Basic Concepts → Chapter #1

• **System of Units
**• **Basic Electrical Quantities
**• **Independent & Dependent Sources
**• **Circuit Analysis
**

Basic Concepts

**Systeme International des Unites – SI:
**• ** Meter (m)
**•

**•**

*Kilogram (Kg)***•**

*Second (s)***•**

*Ampere (A)***•**

*Kelvin (K)*

*Candela (cd)***SI - Standard Prefixes**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

3

Basic Electrical Quantities → Current

**Electric Current – ***rate of change of charge
*

Basic Concepts

**Typical Current Magnitudes
**

�� �� = ����(��)

����
**[A = C/s]
**

** Conventional current flow
+I **→

*represents movement of positive charges***Direct Current (DC)Alternating Current (AC)**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

4

Basic Electrical Quantities → Energy

**Energy – ***ability to do work
*

Basic Concepts

**Flashlight Circuit
**

**w **�� **[J = N∙m]
**

**Convention:
**• **Absorbing Energy: positive current
**

**enters the positive terminal
**

• **Supplying Energy: positive current
enters the negative terminal
**

*Energy AbsorbedEnergy Supplied*

INEL 3105 – Electrical Systems Analysis I 2/19/2018

5

Basic Electrical Quantities → Voltage

**Voltage (potential) -
**• *energy required to move a unit positive charge
*

*between to points with an energy level differential
*

• *difference in energy level of a unit charge located at
each of the two points
*

Basic Concepts

**Typical Voltage Magnitudes
**

���� �� = ����

����
= ���� �� − ���� �� **[V = J/C]
**

** The + and - signs **→

*define a reference direction***Voltage Representations**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

6

Basic Electrical Quantities → Power

**Power (potential) ***– rate of change of energy
*

Basic Concepts

�� = ����

����
= �� ∙ �� **[W = J/s]
**

**passive sign convention: the variable for the
voltage v(t) is defined as the voltage across the
element with the positive reference at the same
terminal that the current variable i(t) is
entering
**

• ** Power positive – power being absorbed
**•

*Power negative – power being supplied***Tellegen’s Theorem: the sum of the
powers absorbed by all elements in an
electrical network is zero!**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

7

Example 1.3

Basic Concepts

**Determine the unknown voltage or current.**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

8

Independent Sources

**A two-terminal element that maintains a specified voltage/current between it
terminals regardless of the current through it.
**

Basic Concepts

• **Voltage Source **• **Current Source**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

9

Problem 1.13

Basic Concepts

**The power absorbed by the BOX in Fig. P1.13 is: �� **∙ ��−����W
**Calculate the amount of charge that enters the BOX between 0.1 and 0.4 seconds.**

INEL 3105 – Electrical Systems Analysis I 2/19/2018

10

Example 1.7

Basic Concepts

**Use Tellegen’s theorem to find the current I0 in the network provided.**