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Interactive e-Learning Tool for Electrical Machines
Michal Kostelný,
Ján Kaňuch
Technical University of Košice, Košice, Slovak Republic;
[email protected]
[email protected]
[email protected]
Viliam Fedák,
Abstract
The contribution presents an application to make easy
the learning of operation of electrical machines. This is a
pilot module having multifunctional structure that is
suitable for full time courses and part-time distance
learning, as well. The matter stars form a standard
content of electrical machines: (1) Transformers, (2) AC
Rotating Electrical Machines and (3) DC Rotating
Electrical Machines. Machines behaviour is visualised by
means of animations. In the paper, the part of electrical
machines dealing with transformers is shown in detail.
Using animations and interactive graphs, the physical
principles, theory of single- and three phase transformers
are explained.
1. Introduction
One of the main goals in the teaching of electrical
machines is to show students physical principles of
operation of electrical machines. Electrical machines
fundamental theory comes out from electromagnetic field
theory that was described by Maxwell equations.
At present in the teaching process of the subject the
blackboard and the transparencies are used. Nevertheless
these methods have some limitations. The use of the
blackboard is not the right method in the case of
representing complex waveforms especially in three phase
systems. With the use of transparencies or slides, some
complex graphical waveforms can be represented, but just
for one or small number of cases.
Based on its principle, the phasor theory was applied
that supposes harmonic supply of the AC electrical
machines. Here an interactive principle is introduced from the physical substance there is derived a construction
of the machine that is fully standardised for single-phase
and three-phase transformers.
The learning materials are universal. They are
presented by primary (main) screens and secondary ones
where the primary screens have „lecture contents” - they
contain animations and interactive graphs and diagrams
showing principles and properties of the no-load
transformer and the transformer under loads of various
characters. Linked to them there are the secondary screens
providing full text. They create a basic tool for selflearning. They are completed by an alternative test
ensuring a revisory function at self-learning. Easy
understandable texts and graphic uniformity offer
comfortable flexibility at learning.
On the other hand, one of the main difficulties in the
learning process mainly of the three phase circuits is to
represent the waveforms of the voltages and currents.
2. Animations
Animation used in the primary screens present the
basic didactic tool for learning process that at learning of
Electrical Machines has the following main functions:
 Physical principle application in constructive
modifications
 High object teaching of phasor theory utilisation
 New unambiguous methodological approach in
theory of three-phase transformers connections
2.1 Transformers Construction
The construction of single-phase and three-phase
transformers is based on two possible magnetic circuits
arrangements: core-type and shell-type ones and from two
different techniques of transformer windings construction:
cylindrical and disc windings. The core-type transformer
presents a dominant construction of transformers and in
prevail cases the windings are cylindrical. By animations
there are presented various types of transformers in the
module. Fig. 1 shows one example of three-phase
transformer with disc windings.
Fig. 1 Three-phase core-type transformer
with disc windings
2.2 Power Balance of Transformers
Other possible type of the animation presented in the
module is shown on example of power balance of the
transformer (Fig. 2) concerning a loaded transformer that
gives a basic idea about calculation of its efficiency.
Fig. 3 Equivalent circuit, equations and phasor diagram of a
loaded transformer
2.4 Connection of Three-Phase Transformers
The methodology used in this module chapter presents
an original contribution to this field that is based on
possible principal connections of the three-phase
transformers – the star and delta connections and the zigzag connection at the low voltage side. The animations
enable to create simultaneously phasor diagrams and the
connection of the windings from set of possible
connections of three phase transformers. The synthetic
principle applied here gives a unique solution. The
marking of windings respect the international valid
labelling. Fig. 4 shows an animation of the very often used
connection Yz1.
Fig. 2 Scheme of transformer power balance
2.3 Phasor Diagrams
The phasor diagrams present a direct application of the
phasor theory. The phasor diagram presents a final
solution that is based on an equivalent circuit and complex
phasor equations and that can be applied directly in the
calculations. The synthetic principle is used in animations
that starts from definition of basic electrical quantities –
from the terminal voltage and current and it enables a
snug calculation of quantities. Fig. 3 shows an example of
a loaded transformer solution.
Fig. 4 Connection Yz1 of a three-phase transformer
3. Interactive Graphs
Interactive graphs enable direct and exact monitoring
of calculations for time courses of basic physical
quantities (currents, voltages, magnetic fluxes) at change
of parameters. In the electrical machines theory they
present the second didactic phenomenon that contributes
to increase visual perception and following, the efficiency
of learning. In the module “Transformers”, the interactive
graphs are applied more times. Here we show two
examples for calculation of time courses.
3.1 Magnetizing Current of Three-Phase
Transformers
Non-harmonics currents that flow through individual
phases at its magnetisation are solved by Fourier analyse
for individual transformer connections. In Fig. 5 there are
courses of magnetizing currents in all phases and courses
of supplied currents for the Dy connection.
Fig. 6 Transient state after connecting the transformer
to the supply network – magnetic flux courses
4. Conclusions
Fig. 5 Magnetizing currents in the Dy connection
3.2 Transient Phenomena in the Transformer
From possible transient phenomena of the transformer,
in the module there are analysed two states:
 Connection of the transformer to the network
 Short-circuit connection across the output winding
The results are obtained by direct application of the
differential equations calculation describing the transient
phenomena. Interactivity of graphic courses of magnetic
flux during the transformer connection to the supply is
shown in Fig. 6.
E-learning principle of the study is extremely suitable
for application in the subject Electrical Machines. Thanks
to the fact that it is the compulsory subject in the bachelor
degree courses in the study programmes of
“Electrotechnical Systems” and “Control Systems in
Mechatronics”, the change of the methodological
approach into new forms of study is almost unavoidable.
The samples from the developed pilot module
“Transformers” prove full validation of the presented
approach.
Animations and interactive graphs present and
extraordinary tool for the primary screens used for
lecturing. Except of the easier understanding it helps to
increase attractiveness of the study of the subject. The
pilot courses will be introduced in the current academic
year. The module for lectures is completed by the module
on “Measurement on Electrical Machines”, that presents a
model package for experimental measurements.
5. References
[1] Glew J.P, Forsyth A.J., Westmancott O., Wallace
W.F., Johnson C.M., Naylor P., Clare J.C.: Creation of
Web-Based Learning Materials for an MSc in Power
Electronics and Drives. Proc. of European Power
Electronics Conference (EPE 2001), Graz.
[2] Marcos J., Quintans, C., Doval, J., Hidalgo, O.,
Nogueiras, A.: E-Learning Tool for DC/AC Converters.
Proc. of Power Electronics and Motion Control Int. Conf.
(EPE-PEMC 2004), Riga, Sept. 2004.
Žilina, Slovakia, July 2005, pp. 387 – 395. ISBN 9963907-63-2.
[3] Ruplis, A, Priednieks, E., Krievs, O. New Learning
Tools for the Course on Electrical Engineering and
Electronics. Proc. int. conf. on Power Electronics and
Motion Control (EPE-PEMC 2004), Riga, Latvia, Sept.
2004.
[9] Fedák, V., Kostelný, M., Kaňuch, J.: E-Learning
Course on Transformers – Animation and Visualisation of
Operation. Joint Czech-Polish Conference on Low
Voltage Electrical Machines, LVEM 2005, Brno –
Šlapanice, Czech Republic, Nov. 2004, pp. 23-32. ISBN
80-214-2632-2.
[4] Fedák, V., Bauer, P., Hájek, V., Weiss H., Nagy I.,
Korondi P. et al: Interactive e-Learning in Electrical
Engineering. Proc. of 15th Int. Conf. on Electrical Drives
and Power Electronics (EDPE 2003), the High Tatras,
Sept. 2003, 368-373. ISBN 80-89114-45-4.
[10] Kostelný, M., Fedák, V., Kaňuch, J.: Interactive Elearning Module on Transformers. Int. Symposium on
Electrical Machines, ISEM 2005, Prague, Czech
Republic, Sept.2005
[5] Weiss, H., Schmidhofer A., Schmid, A. et al:
Animated and Interactive e-Learning Concept and
Realization. The IASTED 2004, Int. Conf. on Web-Based
Education, Innsbruck, Austria, Feb. 2004, paper No 416210. ISBN 0-88986-377-6.
[11] Fedák, V., Bauer P.: E-learning in Electrical
Engineering Education: Opportunities and Challenges.
Proc. of Int. Conf. on Electrical Drives and Power
Electronics (EDPE 2005), Dubrovnik, Croatia, Sept. 2005
[6] Bauer, P., Fedák, V.: Educational Visualization of
Different Aspects for Power Circuits and Electrical
Drives. 11th Power Electronics and Motion Control Int.
Conference, EPE-PEMC 2004. Riga, Latvia, Sept. 2004.
ISBN 9984-32-010-3.
6. Acknowledgement
[7] Fedák, V., Bauer, P., Miksiewicz, R., Weiss H.:
Experience with E-learning for Electrical Engineering from Ideas to Realisation. Int. Conf. on Engineering
Education. Global Education Interlink (ICEE 2005),
Gliwice. Poland, July 2005.
[8] Bauer, P., Fedák, V.: Implementation of E-Learning
Platform for Electrical Engineering, In: Proc. of Computer
Based Learning in Science Int. Conf., CBLIS 2005,
The work was performed within the project „Interactive
and Unified E-Based Education and Training in Electrical
Engineering”, INETELE. The project is supported by the
European Community within framework of Leonardo da
Vinci II programme (project No CZ/02/B/F/PP/134009).
The opinions expressed by the authors do not necessarily
reflect the position of the European Community, nor does
it involve any responsibility on its part.
Achievements in the INETELE project can be followed at
the web site: www.tuke.sk/inetele.
The part of the work was partly supported by the project
of the Slovak Scientific Grant Agency No 1/2178/05.