Objective: We will learn more about transformers and phasor diagrams by setting up and performing measurements with transformer circuits. We will test some of the circuits discussed in lectures and homework problems.

Lab Activities:

1. Use a 1 volt sinusoidal voltage source at 60 Hz applied to the primary side of your transformer (the 120 V AC plug). Make measurements at the secondary terminals to determine the turn ratios and the "dots". the primary and secondary sides of your transformer.

2. Repeat step 1 at frequencies other than 60 Hz, and check whether the turns ratio, a, varies with frequency. You may want to make a plot of a versus frequency. Check a frequency range that spans several decades.

3. Devise measurement procedures that will allow you to estimate the internal resistances of the primary and secondary coils (R₁ and R₂), the self-inductances (L₁ and L₂), and the coefficient of coupling, k.

   Do your measurements agree with the "ideal transformer" assumptions? Compare the ratio L₁ / L₂ with the expected value of [N₁ / N₂]².

   Don't worry about estimating k, and check your estimates for L₁ and L₂ at several frequencies.

4. Attach a 100 ohm load resistor to the secondary, and measure the impedance at the primary terminals, Z_ab, at various frequencies that span several decades. Compare your measurement with analysis based on the ideal transformer model.

5. Set up the circuit shown in Problem 9.80 that you will analyze on Homework 3, and compare your measured results with the analysis.

6. Set up the circuit shown in Problem 9.82 that you will analyze on Homework 3, and compare your measured results with the analysis. We will use a potentiometer for R_x.