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I.
OBJECTIVES
1.
To analyze a parallel AC circuit containing a resistor (R), an inductor (L), and a capacitor (C).
2.
To simulate the RLC circuit and observe the circuit responses.
3.
To build the RLC circuit and measure the circuit responses.
II. PARTS LIST
Equipment
:
IBM PC or Compatible
Function Generator
DMM (Digital Multimeter)
Parts
:
1 – 470 Ω Resistor 1 – 1 µF
Capacitor
1 – 47 mH Inductor
Software
:
MultiSim 11
III. PROCEDURE
A. Theoretical Analysis
1. Given the R, L, & C parallel circuit in Figure 1, calculate the total equivalent admittance, YT, and the impedance, ZT, of the circuit at f =
550
Hz and 1 kHz. List the calculated values in Table 1.
Figure 1: Parallel R, C, L Circuit
|
Frequency Hz |
L & C Admittances in |
Rectangular Form |
|||||
|
Inductor GL – jBL |
Capacitor
GC + jBC |
||||||
|
1000 |
|
Frequency Hz |
Total Circuit Admittance YT |
|||||||||||||
|
Rectangular Form GT + jBT |
Magnitude |
Angle |
||||||||||||
|
Total Circuit Impedance ZT |
| Rectangular Form
RT + jXT |
Table 1 – Calculated RLC Admittance and Impedance Values
2. Calculate and record the following quantities:
| Frequency Hz |
IR (RMS). A |
IC (RMS), A |
IL (RMS). A |
||
Frequency Hz
{IR + IC + IL }= IS (RMS), A
IS = V * YT
550 1000
Table 2 – Calculated RLC Component Current Values
Does the sum of the magnitudes of the three currents IR, IC, and IL, in the table above, equal the current, IS, calculated directly in the last column?
(YES or NO)
Explain why your answer is what it is.
3. Calculate the power dissipated by the parallel resistor and the power supplied by the source:
|
PR, W |
PS, W |
Table 3 – Calculated RLC Resistor Power Dissipation
B. Multisim Simulation and Circuit Calculations
1.
Launch MultiSim and build the circuit schematic shown in Figure 2. Include the AC Power source and the DMMs.
2. Set both DMMs, XMM1 thru’ XMM4, to read AC measurements and Current, I. See fig. 2 below.
Figure 2: MultiSim RLC Parallel Circuit with Instrumentation
3. Activate the simulation and record the current readings for both frequencies:
|
IS (RMS), A |
IR (RMS), A |
IL (RMS), A |
|
550 |
Table 4 – Current Measurements Simulation Results
4.
Do the current values in Table 4 agree with those obtained in Tables, 2, 3, & 4 of Part A? (Circle your answer)
YES NO
5.
Remove the DMMs and attach the wattmeter as shown below:
Figure 3 – AC Power Measurement
6.
Record the measurement from the wattmeter.
| FrequencyHz |
Source Power, PS (Watts) |
Power Factor |
Table 5 – Power Measurement Readings
7.
Do values in the Tables 6 and 2 agree? (Circle your answer)
YES NO
If there is any disagreement investigate the source of error and report your findings below:
C. Construction of a Parallel R, L, C Circuit and Measurement of Circuit Characteristics
1. Construct the circuit in Figure 1.
2. Set the function generator voltage to
2.5
V RMS and the frequency value to 550 Hz.
3. Turn the circuit on.
4. Record the current reading.
IS = _____________ (A)
5. Is this the same as the simulated and calculated value? ________ (YES or NO)
6. Measure and record the branch currents:
IR = ________ (A) IC = ________(A) IL = ________(A)
Are the current readings the same as your calculated and simulated values?
(Circle your answer)
YES NO
If you answered NO, explain why you think they differ.
7. Repeat Steps 2 through 6 with the frequency generator set to output at 1000 Hz. IS = ______________(A)
IR = ________ (A) IC = ________(A) IL = ________(A)
Are the current readings the same as your calculated and simulated values? (Circle your answer) YES NO
If you answered NO, explain why you think they differ.
IV. TROUBLESHOOTING
Describe any problems encountered and how those problems were solved.
