Thevenin and Norton Theorems PDF

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Thevenin and Norton Theorems...

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Thevenin Theorem

A linear two-terminal circuit can be replaced by an equivalent circuit consisting of a voltage source VTh in series with an impedance ZTh. where VTh is the open-circuit voltage at the terminals ZTh is the input or equivalent impedance at the terminals when the independent sources are turned off.

1) Obtain the Thevenin equivalent at terminals a‑b of the circuit

2) Find thevenin equivalent as seen from terminals a‑b

To find VTh:

To find VTh, we apply KCL at node 1 in Figure,

Applying KVL to the loop on the right‑hand side in Figure,

Norton Theorem

a linear two-terminal circuit can be replaced by an equivalent circuit consisting of a current source IN in parallel with an impedance ZN, where IN is the short-circuit current through the terminals, ZN is the input or equivalent impedance at the terminals when the independent sources are turned off. (ZN = ZTh)

Thevenin equivalent

3) Find the Norton equivalent of problem 1.

Since ZN is same as ZTh, ZN = 6.48-j2.64 Ω. To get IN, we short-circuit terminals a-b

Norton equivalent

4) Find Io of the circuit given below:

As evident from the figure, the (8 − j2) and (10 + j4) impedances are short-circuited

Mesh 1:

Supermesh:

Adding eqns (1) and (2)

Practice problems: (Alexander book) 1) Practice Problem 10.8 2) Practice Problem 10.9 3) Practice Problem 10.10...