Direct Current and Transient Analysis 169
Example 2.21
Assuming that the load is RL, determine the Thevenin’s equivalent circuit of the electri-
cal network shown in Figure 2.66 by
a. Hand calculations.
b. Creating the script fi le Thevenin that simulates Thevenin’s theorem consisting in
varying RL over the range 1 ≤ RL ≤ 50 Ω, in steps of 1 Ω, and computing the respec-
tive powers for each value of RL. Recall that the resistance dissipates maximum
power when RL = RTH and its VTH = 2 VRTH.
FIGURE 2.66
Network of Example 2.21.
Vs = 100 V
−
+
I
RL
RL = 1: 1 : 50
a
a′
R 1 = 20 Ω
R 2 = 60 Ω
FIGURE 2.67
Calculated Thevenin’s equivalent circuit of Example 2.21.
−
+
I
VTH = 75 V RL
a
a′
RTH = 15 Ω
ANALYTICAL Solution
Part a
The VTH and RTH are evaluated by hand.
VTH V
60 100
20 60
6000
80
* 75
and
RRRTH
12
20 60
20 60
1200
80
|| * 15
The calculated Thevenin’s equivalent circuit, as seen through the terminals aa’, is shown
in Figure 2.67.