ECEN 2612Mutual Inductance (10.0 Points)Lab #1

ECEN 2612Mutual Inductance (10.0 points)Lab #1

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Partner:

OBJECTIVES: Each student will be able to examine the effects of magnetic coupling and the mutual inductance between two inductor coils using AC circuit measurements.

PROCEDURE: The instructor will describe the equipment to be used. You should be sure to record manufacturers, model numbers, and other identifying numbers, e.g., serial numbers, of test equipment you use. Why might this be important when doing experimental work?

Also note that for this lab we will use the Type 107L General Radio Co. Variable Inductor, not the Type 107N.

Use this circuit to estimate the self-inductance L1 of the stator coil as follows: (0.5 point)

(a)Adjust the function generator signal to be a 10kHz, 6 Vpp sine wave. Use the Agilent 33120Abecause it has much smaller capacitance between signal and case grounds. Make sure to set the generator to High Z output in order for its generator amplitude display to be correct for a high Z output.

(b)Display VR on CH 1 and VL on CH 2 of your oscilloscopeusing 10:1 probes. Consider carefully, and explain, the grounding you use. (Depending on the function generator and the scope you use, you will need to avoid conflicting grounds.)

(c)Vary R (a decade box) until VR = VL in magnitude.

(d)Under the condition in part (c), L1 can be calculated using L1 = R/2f. Explain any assumptions being made, or measure for them. Find L1this way. Compare with an LCR meter measurement of L1.

Repeat step 1 for the rotor coil self-inductance L2. (0.5 point)
Investigate the mutual inductance between the stator (L1) and rotor (L2) coils by setting up this circuit below, and carrying out the following steps. Notice that, with the rotor (V2) open-circuited,

and the sign is determined by the polarity of

with respect to . Hence,

(a)Display V1 on CH 1 and V2 on CH 2, with the function generator as adjusted in 1-a above. Be sure the scope sweep is synchronized to V1. Why should there be no function generator grounds conflict in this circuit? Observe and describe the oscilloscope display as you rotate the rotor coil dial 360o. (1.0 point)

(b)Locate and record the dial position which gives M=0. Compare your result with the formula given on the inductance box. L in the box formula is the dial setting. Sketch the oscilloscope display. (1.0 point)

(c)Set the dial at 5.0, sketch the scope display, and record the amplitudes of V1 and V2. Calculate a value for the mutual inductance using the equation above; call this value Mexp where, , where L1 is the stator self-inductance obtained in step 1.

Substitute the dial setting (L) into the formula on the inductance box to calculate the dial value of mutual inductance and call it Mdial. Compare Mexp with this value obtained from the formula. (1.0 point)

(d)Repeat (c) for a dial setting of 1.0. Repeat all parts of (c), including the sketch. (1.0 point)

(e)Tabulate the data and results for parts (b), (c), and (d). Include dial settings, amplitudes of V1 and V2, Mexp, and Mdial in your table. (0.5 point)

Set up the circuit shown just below by connecting the stator and rotor coils in series. To do this, connect terminal 2 to terminal 3.

(a)With the dial set to give M=0, vary R until VR=VL in magnitude. Then, use the technique in step 1 to calculate the value of the equivalent inductance Leq of the series combination. Since M=0, check your accuracy by comparing the result to the theoretical value . (1.0 point)

(b)Repeat (a) for dial settings of 1.0 and 5.0. Compare with the theoretical values (which sign is for which setting?). Use Mexp for the value of M in this equation. (2.0 point)

(c)Tabulate the data and results for step 4. Include dial settings, the Mexp from step 3, R, Leq as calculated, and the theoretical value of Leq. (0.5 point)

The work above has not included the resistance in the L1 and L2 coils. Measure those resistances, R1 and R2 with the LCR meter set to 10 kHz. Briefly describe how their presence might affect your results. Also describe how their values could be included to improve your results. (1.0 point)

This lab, perhaps more than others, needs very careful descriptionsof data and work.

REPORT: Keep a complete record of all data, results, observations, and answers to questions, written neatly and legibly (preferably in ink) on the unlined side of standard engineering paper. Attach the lab sheet as a cover. This is due at the beginning of the next lab session!

J.Hosseininejad/ P.Munro 14-Jan-2015 02:44 PM (save date)Page 1 of 2