05 February, 2007

Superposition Theorem

The superposition theorem for electric circuits states that the total current in any branch of a bilateral linear circuit equals the algebraic sum of the currents produced by each source acting separately throughout the circuit.

To ascertain the contribution of each individual source, all of the other sources first must be "killed" (set to zero) by:

  • replacing all other voltage sources with a short circuit (thereby eliminating difference of potential. i.e. V=0)
  • replacing all other current sources with an open circuit (thereby eliminating flow of current. i.e. I=0)
This procedure is followed for each source in turn, then the resultant currents are added to determine the true operation of the circuit. The resultant circuit operation is the superposition of the various voltage and current sources.
Example :







When superimposing these values of voltage and current, we have to be very careful to consider polarity (voltage drop) and direction (electron flow), as the values have to be added algebraically.



For more information on this theorem vist the following sites :

www.allaboutcircuits.com/vol_1/chpt_10/6.html

www.wisc-online.com/objects/index.asp?objID=DCE3802

www.ee.adfa.edu.au/staff/hrp/teaching/docs/superThevininMar96.pdf

http://en.wikipedia.org/wiki/Superposition_theorem

http://www.swarthmore.edu/NatSci/echeeve1/Ref/E72WhaKnow/WhaKnow.html

http://www.analyzethat.net/86_superposition_theorem.php

http://utwired.engr.utexas.edu/rgd1/lesson08.cfm

No comments: