A.C. Network Theorems and Principle of Theorems

A.C. Network Theorems List

SUPERPOSITION THEOREM

THEVENIN'S THEOREM

NORTON'S THEOREM

MAXIMUM POWER TRANSFER THEOREM

MILLMAN'S THEOREM

SUBSTITUTION THEOREM

RECIPROCITY THEOREM

Principle of Superposition Theorem:

The principle of Superposition theorem is “The voltage across (or current through) an element in a linear circuit is the algebraic sum of the voltages across that element due to each independent source acting alone. To evaluate the separate currents to be combined, replace all other voltage sources by short circuits and all other current sources by open circuits.

Principle of Thevenin's Theorem:

Thevenin’s theorem states that “ a linear two terminal circuit can be replaced by an equivalent circuit which have a voltage source VTh in series with a resistor RTh where VTh is the open circuit voltage at the terminals and RTh is the effective resistance seen by the terminals.

Principle of Norton's Theorem:

Nortons theorem states that “a linear two terminal circuit can be replaced by an equivalent current source IN in parallel with a resistance RN where RN is the equivalent resistance at the terminals and IN is the short circuit current through the terminals where all the independent sources are not effected by the terminals”.

Principle of Maximum Power Transfer Theorem:

The maximum power transfer theorem states that in a linear , bilateral DC and AC network , maximum power is delivered to the load when the load resistance is equal to the internal resistance of a source.

If it is an independent voltage source, then its series resistance (internal resistance Rs) or if it is independent current source, then its parallel resistance (internal resistance Rs) must equal to the load resistance RL to deliver maximum power to the load.

Principle of Millman's Theorem:

The utility of Millman’s Theorem is that the number of parallel voltage sources can be reduced to one equivalent source. It is applicable only to solve the parallel branch with one resistance connected to one voltage source or current source. It is also used in solving network having an unbalanced bridge circuit.

Principle of Substitution Theorem:

Substitution Theorem states that the voltage across any branch or the current through that branch of a network being known, the branch can be replaced by the combination of various elements that will make the same voltage and current through that branch.

Principle of Reciprocity Theorem:

Reciprocity theorem states that In any bilateral linear circuits; If a source of EMF “V” acting in a branch (let “A”) of the circuit produces the current “I” in another branch (let “B”) of the circuit. Then when the EMF “V” acts in the second branch “B” , it will produce the same current “I” in the first branch “A”.

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