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EEL1176 Lab 2 - Lab experiment for chapter 3

Lab experiment for chapter 3

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Field Theory

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Multimedia University

Academic year: 2015/2016

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Field Theory EEL1176 FT2 Experiment FT2: Measurement of Inductance and Mutual Inductance Name: ID: 1. Objectives: To examine the effect of magnetic inductance of the given circuit. To measure self inductance and mutual inductance. 2. Dual Trace Oscilloscope Function Generator Digital Multimeter 12V power supply Transformer (ratio part no.: Resistor 1 (2 units) Operational amplifier IC LM741 Breadboard 3. Theory: When electric current flows through a conductor, a magnetic field is immediately brought into existence in the space surrounding the conductor. The magnetic field is produced essentially the electrons moving in the conductor. The opposite is also true, i., when a magnetic field embracing a conductor moves relative to the conductor, it produces a flow of electrons. This phenomenon, where an electromotive force (e.m), and hence current (i. flow of electrons), is induced in any conductor that cut across or is cut a magnetic flux, is known as electromagnetic induction. Figure 1: Electromagnetic induction set up. Page 1 of 8 Field Theory EEL1176 FT2 Imagine a coil of wire, similar to the one shown in Figure 1, connected to an ac supply. It is found that whenever an effort is made to increase current through it, it is always opposed the instantaneous production of counter e.m of Energy required to overcome this opposition is supplied the ac supply. This energy is stored in the form of additional flux produced. If, now, an effort is made to decrease the current then again it is delayed due to the production of e.m, this time in the opposite direction. This property of the coil which opposes any increase or decrease of current through it is known as In Figure 1, any change of current in the primary coil is always accompanied the production of mutually induced e.m in the secondary coil. A mutual inductance M may be defined to quantify the ability of one coil to produce an e.m in a near coil induction when the current in the first coil changes. This action is reciprocal, i., the second coil can also induce an e.m. in the first one when the current in the second coil changes. The device in Figure 1 is known as a transformer. It can transfer electrical energy from one circuit to another at the same frequency. The two coils or windings are electrically isolated from each other (infinite resistance between them), but magnetically linked through the iron core. According to law, when current I1 flows in the primary winding, the induced e.m. in the secondary winding is emf M dI 1 dt If the secondary circuit is closed, for example, connecting a resistor to the terminals, a current I2 will start to flow. this electromagnetic induction, the electrical energy is transferred from the primary winding to the secondary winding means of magnetic field coupling. Assuming that there is no loss of power and no flux leakage, the apparent output power in the secondary circuit will be equal to the apparent input power in the primary circuit. The output voltage can be higher or lower than the primary circuit voltage according to a fixed ratio. This ratio is equal to the ratio of the number of turns of the secondary winding to that of primary winding, i. N2 N1. This ratio is known as the Voltage Transformation Ratio, K. One method to measure self and mutual inductance is using the bridge as shown in Figure 2. In this experiment, the self and mutual inductance of transformer windings are measured. For each winding, the self inductance can be modeled as a pure inductor in series with a resistance. The impedance is therefore Z R or R2 Page 2 of 8 (1) Field Theory EEL1176 FT2 4. Procedure: Transformer 1 3 6 4 1 2 3 6 5 4 Figure 3: Transformer winding connections. Part A: Resistance measurement and Oscilloscope Connections 1. using a multimeter, measure the resistance of the primary winding (between terminals 1 and 6), the secondary winding (between terminals 3 and 4), and the resistance between the primary and the secondary windings (between terminals 1 and 3). Is there any electrical connection between the primary winding and the secondary winding? 2. Set both CH1 and CH2 of the oscilloscope to AC coupling (i. the switch in the AC position). Make sure the vertical sensitivity knob is in the position. 3. Set to to to and to 4. Set the Function Generator for a 2 kHz sine wave and connect the output to terminals 1 and 6 of the transformer. 5. Connect a probe from CH1 of the oscilloscope to terminals 1 and 6. 6. Adjust the Function Generator sine wave amplitude to 0 V. 7. Connect the second probe from CH2 of the oscilloscope to terminals 3 and 4. 8. Sketch the waveforms displayed on the oscilloscope and label the traces (CH1 and CH2). Page 4 of 8 Field Theory EEL1176 FT2 Part B: Measurement of Self Inductance Oscilloscope Function Generator V1 0 Vpeak 1 3 I1 CH1 CH2 4 6 RF VCC DC Power Supply Gnd VF VEE Figure 4: Measurement setup for inductance measurement. 1. With the Function Generator set to 2 kHz sine wave, with 0 V amplitude, construct the circuit (with resistor RF 1 shown in Figure 4. 2. Connect a probe from CH1 of the oscilloscope to terminal 1 of the transformer. The grounding wire of the probe should be connected to ground conductor of the circuit. Measure the voltage V1 from the oscilloscope. 3. Connect a probe from CH2 of the oscilloscope to the output. The grounding wire of the probe should be connected to ground conductor of the circuit. Measure the voltage VF from the oscilloscope. 4. Repeat the experiment for different frequencies from 2 kHz to 20 kHz. Measure the voltage V1 and VF and record the results in Table 1. 5. Plot the graphs of impedance (Z) vs. frequency (f) and (L) vs. frequency (f). 6. At the frequency of 20 kHz, sketch the waveforms displayed on the oscilloscope and label the traces (CH1 and CH2). Note: Resistance of the winding has been measured in Part A. Page 5 of 8 Field Theory EEL1176 FT2 5. MEASUREMENT RESULTS AND DISCUSSIONS Part A Resistance of the primary winding Resistance of the secondary winding Resistance between the primary and the secondary windings Ratio of the secondary voltage to the primary voltage, V2 V1 Discussions: 1. Discuss method to increase the measurement accuracy of the resistance. 2. Will there be any current flow if a battery is connected between terminals 1 and 3 of the transformer? Explain your answer. 3. Determine the phase relationship between the primary and the secondary voltage waveforms. Part B Table 1: Frequency, f (kHz) V1, peak (V) VF, peak (V) Impedance, Z Self Inductance, L 2 4 6 8 10 12 14 16 18 20 Discussions: 4. Propose a method to reduce the error in measuring the voltages using the oscilloscope. 5. Determine the phase relationship of the two waveforms. 6. Is the graph of Z versus f a perfect straight line? If not, investigate the causes of deviation. 7. Is the graph of L versus f a perfect straight line? If not, investigate the causes of deviation. 8. Justify whether the measurement results are satisfactory. Page 7 of 8 Field Theory EEL1176 FT2 Part C Table 2: Frequency, f (kHz) V2, peak (V) VF, peak (V) Impedance, Z Mutual Inductance, M21 2 4 6 8 10 12 14 16 18 20 Discussions: 9. Is the graph of M12 versus f a perfect straight line? If not, investigate the causes of the deviation. 10. Justify whether the measurement results are satisfactory. 6. LABORATORY REPORT The report should contain the following: (1) This lab sheet (covering the Objectives, List of Basic Theory, and Tabulation of observed and computed data). (2) Graphs of the measurement results (3) Discussions, and (4) Conclusion. Please obtain signature from the lecturer before you leave the lab: Date : IMPORTANT NOTES TO THE STUDENTS: 1. Read the lab sheet before attending the experiment session. 2. Bring along the necessary GRAPH PAPERS and calculator to the lab. 3. The completed laboratory report must be submitted to the laboratory technician AT THE END OF THE EXPERIMENT SESSION. 4. Each student is required to submit an INDIVIDUAL REPORT. Page 8 of 8

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EEL1176 Lab 2 - Lab experiment for chapter 3

Course: Field Theory

9 Documents

Students shared 9 documents in this course

University: Multimedia University

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Field Theory EEL1176 FT2

Page 1 of 8

Experiment FT2: Measurement of Inductance and Mutual Inductance

Name: ___________________________ ID: _________________

Objectives:

• To examine the effect of magnetic inductance of the given circuit.

• To measure self inductance and mutual inductance.

2. Apparatus/Components:

• Dual Trace Oscilloscope

• Function Generator

• Digital Multimeter

• +/- 12V power supply

• Transformer (ratio 1:1+1, part no.: RS196-375)

• Resistor 1 kΩ (2 units)

• Operational amplifier IC LM741

• Breadboard

3. Theory:

When electric current flows

through a conductor, a

magnetic field is immediately

brought into existence in the

space surrounding the

conductor. The magnetic field

is produced essentially by the

electrons moving in the

conductor. The opposite is also

true, i.e., when a magnetic field

embracing a conductor moves

relative to the conductor, it

produces a flow of electrons.

This phenomenon, whereby an

electromotive force (e.m.f),

and hence current (i.e. flow of

electrons), is induced in any

conductor that cut across or is

cut by a magnetic flux, is

known as electromagnetic

induction.

ΙΙ

Figure 1: Electromagnetic induction set up.

EEL1176 Lab 2 - Lab experiment for chapter 3

Field Theory

Multimedia University

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EEL1176 Lab 2 - Lab experiment for chapter 3

Course: Field Theory

University: Multimedia University

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