ECET210 Week 2 iLab2 | Complete Solution

Laboratory Procedures
DeVry University
College of Engineering and Information Sciences

I.OBJECTIVES

1. To analyze a series AC circuit containing an inductor (L) and a resistor (R) using Ohm’s Law and Kirchhoff’s Voltage Law.

2. To simulate the RL circuit and observe the voltage drops and currents at different frequencies.

1. To build a RL circuit and measure voltage drops and current at different frequencies.

1. To prove that the power delivered by the source is equal to the sum total of power dissipated by all of the resistors in the circuit.

II.        PARTS LIST

Equipment:
 

         IBM PC or Compatible                      

                             Function Generator

DMM (Digital Multimeter)

Parts:
1 - 470 Ω  Resistor                  1 - 47 mH Inductor

 Software;
 

 MultiSim 11

III.       PROCEDURE
 

A.        Theoretical Analysis

1. Given the R & L series circuit in Figure 1, calculate the total equivalent impedance, ZT , of the circuit at frequencies, f = 1 kHz, 2kHz and 3 kHz, and list the values obtained in Table 1.    

Figure 1: Series R L Circuit

Note: Notice that the self resistance, RL of the 47 mH inductor is shown in the schematic. This should be included in the analysis, as it is present with the inductor, since the inductor is a wire-wound component. Before starting the lab, measure the coil resistance with a DMM and include the value in the ensuing calculations.

Frequency (kHz)

Reactance, XL

(Ω)

Inductive Impedance ZL

Total Series Circuit Impedance ZT

Rectangular Form

RL + j XL

Rectangular Form

[R + RL] + jXL

Magnitude

Angle

1

2

3

Table 1 – RL Circuit-Calculated Impedance Values

1. Calculate and record the following quantities: 

Frequency (kHz)

IS (RMS) = VS / ZT  (A)

Power Factor

Rectangular Form

Magnitude

Angle

1

2

3

Table 2 – RL Circuit-Calculated Current Values

Frequency (kHz)

VL (RMS) – (Volts)

Rectangular Form

Magnitude

Angle

1

2

3

Table 3 – RL Circuit-Calculated Inductor Voltage Values

Frequency (kHz)

VR (RMS) - (Volts)

{VL + VR}(RMS) -

           (Volts)

Rectangular Form

Magnitude

Angle

1

2

3

Table 4 – RL Circuit-Calculated Voltage Values

1. Does the sum of the 2 voltage drops in Table 4 equal 2.5 VRMS ?

                                                         (YES or NO)

Explain why your answer is what it is.
 

1. Calculate the power dissipated in the series resistor of this circuit and the power supplied by the source:

Frequency (kHz)

PR

(W)

PS

(W)

1

2

3

Table 5 - Source Power and Power Dissipation

B.        MultiSim Simulation and Circuit Calculations

1. Launch MultiSim and build the circuits shown in Figure 2. Include the AC power source and connect the DMMs.

Figure 2 – MultiSim RL Circuit with Instrumentation

1. The MultiSim AC power source has the facility to choose RMS value for the voltage in addition to frequency and the phase. Type 2.5 in the voltage window of the power-source dialog box.

2. Choose any one frequency (1kHz, 2 kHz, or 3 kHz) for the source used in Section A. In Figure 2, a source frequency of 1 kHz is used.

1. Set both DMMs, XMM1 and XMM2, to read AC measurements and Voltage (V). Set the DMM, XMM3, to read AC RMS Current.

1. Expand the DMMs, activate the MultiSim simulation, and record the voltage and current readings in Table 5.

Frequency (kHz)

IS (RMS)
(Amps)

VL (RMS)
(Volts)

  VR (RMS)   (Volts)

Table 5 - MultiSim Simulation Results

1. Do the (simulated) voltage and the current values in Table 5 agree with those obtained in Tables, 2, 3, and  4 of Part A? (Circle your answer). 

                                                            YES             NO

1. Remove the DMMs from the circuit and enable the wattmeter from the instrument menu, as shown in Figure 3.

Figure 3 - AC Power Measurement with Wattmeter

1. Turn the simulator ON and note the Power in Watts and the Power Factor as displayed by the simulator wattmeter instrument.

Frequency

(kHz)

Source Power, PS

(Watts)

Power Factor

Table 6 - Power Measurement Readings

1. Do the numbers in Table 6 agree with those in Table 2?

YES             NO

If there is any disagreement, investigate the source of error and report your findings below:

C.        Construction of a Series R L Circuit and Measurement of Circuit Characteristics

1. Construct the circuit in Figure 1.

2. Set the function generator voltage to 2.5 V RMS. Set the frequency to the same value used in the simulator experiment.

3. Set DMM to measure AC current and make the appropriate connections. Switch the function generator power ON.

4.  Record the current reading.       

IS = _____________ (A)

1.  Is this the same as the simulated and calculated value? ________ (YES or NO)

2. Switch OFF the AC input power. Remove the DMM and re-configure it to measure voltages. Reconnect the circuit and apply power. Measure the voltage across L and R, one at a time.

3.  Record these voltages.

VL = ________    (V)      VR  = ________(V)       

Are the voltage readings the same as your calculated and simulated values?

 __________ (YES or NO)

1. If you answered NO, explain why you think they differ.

IV.       TROUBLESHOOTING

        Describe any problems encountered and how those problems were solved.