Back to School – Let’s Calculate Current I3 _ EEP

Back To School – Let’s Calculate Current I3Back To School – Let’s Calculate Current I3

Techniques for solving DC circuitsTechniques for solving DC circuits

Referring to the following circuit, calculate Referring to the following circuit, calculate direct current Idirect current I33::

Using Kirchhoff’s laws;Using Kirchhoff’s laws;1.

Using nodal analysis;Using nodal analysis;2.

Applying Applying Thévenin’s theoremThévenin’s theorem at nodes at nodes AA and and BB..3.

Ok, let’s dive into calculation…Ok, let’s dive into calculation…

For start, let’s try to remember two Kirchhoff’s Laws //For start, let’s try to remember two Kirchhoff’s Laws //

Kirchhoff’s Current Law –Kirchhoff’s Current Law – The algebraic sum of currents at a node is zero. The algebraic sum of currents at a node is zero.

Kirchhoff’s Voltage Law –Kirchhoff’s Voltage Law – The algebraic sum of voltages around a closed The algebraic sum of voltages around a closed

circuit loop is zero.circuit loop is zero.

– KCL– KCL stands for Kirchhoff’s Current Law stands for Kirchhoff’s Current Law

– KVL– KVL stands for Kirchhoff’s Voltage Law stands for Kirchhoff’s Voltage Law

The following equation can be written:The following equation can be written:

Back To School – Let’s Calculate Current I3 | EEP http://electrical-engineering-portal.com/back-to-school-lets-calculate-curr...

1 of 5 8/4/2015 1:45 PM

Substituting values, we obtain:Substituting values, we obtain:

Finally,Finally,

Thévenin’s voltage Thévenin’s voltage UUThTh at nodes A and B at nodes A and B

can be easily calculated by disconnectingcan be easily calculated by disconnecting

the right part of the circuit:the right part of the circuit:

Thévenin’s equivalentThévenin’s equivalent

resistance resistance RRThTh is the is the

resistance resistance “seen” from“seen” from

nodes A and Bnodes A and B, when all generators are, when all generators are

deactivated (in our case, deactivated (in our case, only Eonly E11 is present is present):):

The left side of the circuit can now beThe left side of the circuit can now be

substituted by substituted by its Thévenin equivalentits Thévenin equivalent, in, in

order to calculate order to calculate current Icurrent I33::

This single-mesh circuit can be easily solvedThis single-mesh circuit can be easily solved

using KVL (Kirchhoff’s voltage law):using KVL (Kirchhoff’s voltage law):


2 of 5 8/4/2015 1:45 PM

Readers should note that Readers should note that UUAB0AB0 ≠ U ≠ UABAB::

UUABAB = U = UThTh – R – RThTh · I · I33 = 8.333 – 4.166 · 0.041 = = 8.333 – 4.166 · 0.041 = 8.1638.163

Comparing the three methods, Comparing the three methods, we can conclude that Thévenin’s theorem is verywe can conclude that Thévenin’s theorem is very

powerfulpowerful, in particular when a single current value is needed., in particular when a single current value is needed.

Another Kirchhoff’s Laws Worked Example (VIDEO)Another Kirchhoff’s Laws Worked Example (VIDEO)


3 of 5 8/4/2015 1:45 PM

Cant see this video? Click Cant see this video? Click herehere to watch it on Youtube. to watch it on Youtube.

Thevenin’s Theorem. Example with solution (VIDEO)Thevenin’s Theorem. Example with solution (VIDEO)


4 of 5 8/4/2015 1:45 PM

Share with engineers //Share with engineers //

Cant see this video? Click Cant see this video? Click herehere to watch it on Youtube. to watch it on Youtube.

Reference //Reference // Fundamentals of electric power engineering – Ceraolo, Massimo, Davide Fundamentals of electric power engineering – Ceraolo, Massimo, Davide

Poli.Poli.

Recommended EE articles //Recommended EE articles //

About Author //About Author //

Edvard CsanyiEdvard Csanyi

EdvardEdvard - - Electrical engineer, programmer and founder of Electrical engineer, programmer and founder of EEPEEP..

Highly specialized for design of LV high power busbar trunkingHighly specialized for design of LV high power busbar trunking

(<6300A) in power substations, buildings and industry fascilities.(<6300A) in power substations, buildings and industry fascilities.

Designing of LV/MV switchgears.Professional in AutoCADDesigning of LV/MV switchgears.Professional in AutoCAD

programming and web-design.Present on programming and web-design.Present on Google+Google+

© 2015 EEP - Electrical Engineering Portal. All Rights Reserved | © 2015 EEP - Electrical Engineering Portal. All Rights Reserved | Privacy PolicyPrivacy Policy | 27 queries in 0.116 seconds. | 27 queries in 0.116 seconds.

Powered by Powered by CsanyiGroupCsanyiGroup


5 of 5 8/4/2015 1:45 PM

Back to School – Let’s Calculate Current I3 _ EEP

Documents

Transcript of Back to School – Let’s Calculate Current I3 _ EEP