ECE 3074
Experiment 27: Complex Power in AC Circuit Analysis
Name: ______________________
Date: _____________________
Analysis:
1. Enter the impedance of the load for the circuit for the three resistors R2 = 220, 470, and 820 Ω using a
value of 50 Ω for R1 in the table to the right of the circuit.
A
Load
R2
Impedance of Load
220 
470 
820 
B
2. To obtain a real impedance, the value of the capacitor placed in parallel with the load is ________.
Show that this is true analytically and by simulating the circuit in PSpice.
Insert appropriate plots from PSpice and MatLAB with an explanation.
3.
The real power, the reactive power, the apparent power, and the power factor for the circuit with each
resistor.
Table 1: Calculated Power
Real
Power
(mW)
Load
Reactive
Power
(mVAR)
Apparent
Power
(mVA)
Power
Factor
(pf)
220 Ω
470 Ω
820 Ω
[820 Ω+5mH || C]
3. Enter phase angle between the current and the voltage for the circuit with each resistor in Table 2.
Table 2: Calculated current and phase angle.
Load
Current
Magnitude
(mA)
Current
Phase Angle
(deg)
220 Ω
470 Ω
820 Ω
[820 Ω+5mH || C]
Measurements:
4. The measured internal resistance of the 5 mH inductor is _____________.
5. Measured instantaneous power, p(t), for each value of R2 (CH1*CH2)
Figure X: Graph of the instantaneous power, p(t) when R2 = 220 

Figure X: Graph of the instantaneous power, p(t) when R2 = 470 

Figure X: Graph of the instantaneous power, p(t) when R2 = 820 

Figure X: Graph of the instantaneous power, p(t) when the load is 820  +5mH || C
6. In the Table 3, enter the amplitude and phase of the current, the maximum and minimum values of the
instantaneous power, and its frequency, taking the voltage as the reference for the zero of phase angle.
Table 3: Experimental values of current and power.
Load
Current
Magnitude
(mA)
220 Ω
470 Ω
820 Ω
[820 Ω+5mH || C]
6. Results obtained from the MatLAB program.
Current
Phase
Angle
(deg)
p(t)max
(mW)
p(t)min
(mW)
p(t)
Frequency
(Hz)
Figure X: Graph of the voltage/current waveform when R2 = 220 

Figure X: Graph of voltage/current waveform when R2 = 470 

Figure X: Graph of the voltage/current waveform when R2 = 820 

Figure X: Graph of the voltage/current waveform when the load is 820  +5mH || C
7. Enter the real, reactive and apparent power and the power factor for each circuit obtained using the
m-file associated with this experiment, complexpowerlab.m, in Table 4.
Table 4: Power parameters derived from experimental data.
Load
Real Power
(mW)
Reactive
Power
(mVAR)
Apparent
Power
(mVA)
Power
Factor
(pf)
220 Ω
470 Ω
820 Ω
[820 Ω+5mH || C]
8. Verify that the real power in the compensated circuit is the same as in the uncompensated circuit.
9. Compute the percent deviation of the measured phase angle, the apparent power, the average power,
and the reactive power from the analytical results. Provide an explanation for the deviations.