Electrical Principles - Chapter 4: Inductors
Publish Date: Mar 27, 2013
Overview
The Electrical Principles/Fundamentals series present the basic theories and concepts taught at entry level electronics courses
both 2 year and 4 year institutions. This series of content provides examples to professors to enable them to easily teach conce
to students, who can develop a solid underlying knowledge of electronics using the NI solution. This series focuses on some of
basic theory as well as providing the NI Multisim circuits to enable practical implementation end experimentation as homework
students.
Table of Contents
1.
2.
3.
4.
5.
6.
7.
In this Chapter
Example Courses
Inductors in Series
Inductors in Parallel
Example Problem
Suggested NI Solution
References
1. In this Chapter
We begin by exploring one of the basic components in a circuit: the inductor. We learn how to simplify a circuit with series and
parallel combinations of inductance to calculate the equivalent inductor value. We will use the NI Multisim circuit teaching
environment to verify our calculated results with example circuits that can be used by any educator or student.
If you do not have NI Multisim installed on your computer, you can download a free 30 day evaluation at
http://www.ni.com/multisim/try/ (http://www.ni.com/multisim/try/)
2. Example Courses
Listed below are example courses that teach this concept at their schools.
Course Name
School
Learn More
Electrical
Principles
Conestoga College
http://www.conestogac.on.ca/fulltime/0071.jsp
Electronic
Technology 1
Macomb
Community College
http://www.macomb.edu/noncms/Search/Courses/coursekey.asp?coursekey=ELEC-11
3. Inductors in Series
In series, the equivalent inductance is simply the summation of the individual values of all the inductors in series.
Leq = L1 + L2 + ... + Ln (n = number of inductors) [1]
4. Inductors in Parallel
As for a combination of inductors connected in parallel, the equivalent inductance is equal to the summation of the reciprocal
values of each inductor:
1/Leq = 1/L1 + 1/L2 + ... + 1/Ln (n = number of inductors) [2]
5. Example Problem
Let us now examine the following circuit and calculate the equivalent inductance.
STEP 1: Open circuit file “inductors_example.ms12”. You will notice the circuit below [3].
Answer Sub-Step 1: Calculate equivalent inductance Leq for the above circuit.
We have a combination of series and parallel inductors. Break the combinations down and solve one combination at a time.
Answer Sub-Step 2: Calculate the equivalent inductance L
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for L and L .
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Answer Sub-Step 2: Calculate the equivalent inductance Lparallel for L5 and L6.
Lparallel = 1/(1/L5) + (1/L6)) = 2.39 H
The resulting circuit will look like this:
Answer Sub-Step 3: Calculate the equivalent inductance Lseries for L3 , L4 and Lparallel.
Lseries = L3 + L4 + Lparallel = 16.39 H
The resulting circuit will look like this:
Answer Sub-Step 4: Calculate the equivalent inductance Lparallel for L2 and Lseries.
Lparallel = 1/((1/L2) + 1/Lseries)) = 5.38 H
And the resulting circuit is as follows:
Answer Sub-Step 5: Calculate the equivalent inductance Leq for L1 and Lparallel.
Leq = L1 + Lparallel = 7.38 H
The final equivalent circuit is shown below:
STEP 2: Open circuit file “inductors_eq_circuit.ms12” in NI Multisim. You will notice the above circuit. Double-click on the
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STEP 2: Open circuit file “inductors_eq_circuit.ms12” in NI Multisim. You will notice the above circuit. Double-click on the
multimeter instrument XMM1 to open its front panel. Then run the simulation by selecting “Simulation>>Run Simulation”. You w
notice the results below.
STEP 3: In Multisim and using circuit file “inductors_example.ms12”, place a multimeter XMM1 in series as shown below. (Click
the multimeter instrument is located in the instruments’ bar on the right hand side of the screen). Then double-click on the
instrument to open its front panel and choose “A” to measure current. Run the simulation by choosing “Simulation>>Run
Simulation”. You will notice the results below.
6. Suggested NI Solution
National Instruments offers a number of products that combine to provide a scalable and powerful teaching platform for educato
The solution includes:
NI Multisim circuit teaching environment: Combining an intuitive circuit definition environment, with powerful SPICE simulation
technology, educators can use NI Multisim to easily teach the ins-and-outs of circuits in a safe environment.
NI ELVIS teaching and measurement platform allows educators to provide students with a compact, all-in-one unit for their
measurement and analysis needs. Combining an oscilloscope, function generator, DMM, bode analyzer and 8 other instrument
into a small platform; it simplifies the laboratory experience for students and lab instructors.
7. References
[1] Hoppe, Patrick. Wisconsin Technical College System. “Wisc-Online”. Series Inductance.
[http://www.wisc-online.com/objects/ViewObject.aspx?ID=DCE2302]. (05/02/2013)
[2] Hoppe, Patrick. Wisconsin Technical College System. “Wisc-Online”. Inductors in Parallel.
[http://www.wisc-online.com/objects/ViewObject.aspx?ID=DCE3302]. (05/02/2013)
[3] Hoppe, Patrick. Wisconsin Technical College System. “Wisc-Online”. Inductors Series – Parallel: Practice Problems.
[http://www.wisc-online.com/objects/ViewObject.aspx?ID=DCE3702]. (05/02/2013)
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