Lab 6

.pdf

School

Auburn University *

*We aren’t endorsed by this school

Course

2110

Subject

Electrical Engineering

Date

Apr 3, 2024

Type

pdf

Pages

Uploaded by SargentWildcatMaster931

ELEC-2110 Electric Circuit Analysis FROM: Jonathan Leviner TO: Tanner Grider DATE: October 5, 2020 LAB SECTION: 001 Electrical Measurements: Thevenin Equivalent Circuits

Jonathan Leviner Electrical Measurements: Thevenin Circuits October 5, 2020 1 of 6 Introduction This lab serves to continue building upon the skills learned in previous labs as well as introducing new theorems used to solve different circuits. The new theorems being introduced are Thevenin’s and Norton’s equivalents. Specifically, the student will be working with linear circuits in order to find their Thevenin and Norton equivalents. Exercise 1 Process and Data: This exercise asks students to show how the voltage at nodes A and B in Figure 1 are equal to V oc /2 when a resistor connected to those nodes, R load , is equal to the Thevenin resistance using a mathematical derivation. The student should start by creating the Thevenin Equivalent circuit. An example is shown in Figure 1. Once created, the student should use voltage division to derive the equation that shows how this scenario is possible. Figure 1: VAB = Voc/2 when Rload = RTh 𝑽𝑽 𝑨𝑨𝑨𝑨 = 𝑹𝑹 𝑻𝑻𝑻𝑻 𝑹𝑹 𝒍𝒍𝒍𝒍𝒍𝒍𝒍𝒍 + 𝑹𝑹 𝑻𝑻𝑻𝑻 × 𝑽𝑽 𝒍𝒍𝒐𝒐 If 𝑹𝑹 𝒍𝒍𝒍𝒍𝒍𝒍𝒍𝒍 = 𝑹𝑹 𝑻𝑻𝑻𝑻 , then 𝑽𝑽 𝑨𝑨𝑨𝑨 = 𝑽𝑽 𝒍𝒍𝒐𝒐 𝟐𝟐 Equation 1: Voltage Division Results: Using the circuit in Figure 1, the student can better visualize how each of the nodes are equal to V oc /2. In order to solve this, the student first needs to assume that R load is equal to R Th . According to Equation 1, since R load is equal to R Th , V AB should be equal to V oc /2. This can be visualized by removing the resistor between nodes A and B, thus creating an open circuit. If you completely removed R load , the voltages of each node would be equal to V oc /2 since they are only connected to the source, V oc .

Jonathan Leviner Electrical Measurements: Thevenin Circuits October 5, 2020 2 of 6 Exercise 2 Process and Data: In this next exercise, the student is tasked with measuring the resistance between each pin of the variable resistor. This can be done using a multimeter set to measure resistance. Once the values have been measured, the student should create a table to record them. After recording the values, the student should sum the measurements of pins 1 and 2 with pins 2 and 3 and record the sum as well. The sum should be roughly equal to 10 kΩ, which happens to be the equivalent resistance of the variable resistor. The student should also be aware that adjusting the wiper on the resistor will affect their measurements. Table 1: Resistances Between Pins Resistances Between Pins Measured Value Pin 1 – Pin 2 2.15 k Ω Pin 2 – Pin 3 7.88 k Ω Pin 1 – Pin 3 9.88 k Ω Sum of 1 – 2 and 2 – 3 10.03 k Ω Results: Using a multimeter, the student should measure the values between each pin of the variable resistor. Once each resistance has been measured, their values should be recorded in a table, as shown in Table 1. Then the student should sum the values of pins 1 to 2 and 2 to 3. The sum of these two should be roughly equal to 10 kΩ . The student should also observe that the sum and the value between pins 1 and 3 should be nearly equal as well. Exercise 3 Process and Data: In this exercise, the student will find the Thevenin equivalents for three different black box circuits using the NI ELVIS board and the variable resistor. When the student has correctly set up the ELVIS board, they should connect the first black box to the 15V power supply via terminals A 1 -A 2 . Once connected, the student will begin to take their measurements, starting with the power supply. Next, they should measure the voltage at terminals B 1 -B 2 on the black box. This gives the value of V oc . When V oc has been found, the student should calculate and record V oc /2. The breadboard should then be switched off, the variable resistor should be connected to terminals B 1 -B 2 , and the voltage drop across the variable resistor should be measured. This should be equal to V oc /2. Next, the student should disconnect the variable resistor from B 1 -B 2 and measure its resistance, R Th . Finally, the student will draw out the Thevenin equivalent circuit and calculate I SC using Equation 2. These steps should be repeated for the second and third black box, and all values should be recorded in a table.

Your preview ends here

Eager to read complete document? Join bartleby learn and gain access to the full version