Learndrives

General Course of Electrical Drives

General Course of Electrical Drives

[02/21/20]   Q:
Can I do my lab in some other day instead of the one indicated in the Lab Distribution file?

A:
You shouldn't. Follow your schedule please, since the number of students in teams is limited to 3 in terms of safety.

[01/03/20]   Q:
My preliminary grade in Moodle is 3. Does it mean that after 7.01.20 my final grade becomes 3 without exam?

A:
Sure! Visit the exam to get more (or less 😉) only if you are not satisfied it.

[01/03/20]   Q:
If I will come to the exam, is there a risk of getting a lower grade than my quiz score, or are these bonus points added to the examination score? Meaning I can try to improve the final grade, but my score is already guaranteed even if I decide to take the exam?

A:
If you decide to visit exam, your score will be zeroed before (quiz score is not the bonus, but a preliminary grade). As usual, every student has two attempts – exam and re-exam, in case of failing.

[01/03/20]   Q:
It has been unclear to me do I have to take exam in EEV5040 e-learning course even when my grades from quizzes satisfy me?

A:
No. As soon as you pass successfully 4 lab reports, your quiz grade becomes your final grade. If you failed reports, you need to correct and re-upload them. If you did not upload reports, you have to upload them. If you missed labs, you fail this course.

[12/09/19]   Q:
Does the scalar or vector control increase the breakdown torque?

A:
Passport breakdown torque is high in induction motor. It is no need to increase it.

[12/09/19]   Q:
Explain please the difference between close-loop and sensorless controls.

A:
To arrange the feedback in the close-loop control, sensors are required. For example, in vector (DTC) control current and voltage sensors are applied, and in lab 3 the rotor position encoder is used. On the contrast, no sensors are needed for direct grid supply and scalar control, for example, in labs 1, 2 and 4.

[12/07/19]   Q:
What does it mean “overloading”? Does it relate to breakdown torque or voltage?

A:
Overload capacity definition is on page 62 in the main textbook. Any induction motor torque (breakdown, starting) depends on voltage (formula 6.7 and Lab. 4). At the scalar control, voltage and frequency have to be adjusted together (Lab. 4) without sensors, and at the vector control – more accurately with sensors and other additional blocks.

[12/06/19]   Q:
Could you please clarify the differences between direct grid supply, scalar control, and vector (or DTC) control?

A:
As you move from the first to last, the cost, design complexity, speed range, and accuracy (smoothness) increase, often along with the starting time, because of torque and current adjustment.

[12/04/19]   The problems with Moodle were resolved by 8 am this morning. The courses, where errors were reported, have been checked. Running tests in Moodle has been restored. If you have any problems in running the tests/quizes or with their results, please contact us at [email protected].

We apologize for any inconveniences. We will do our best to prevent such situations in the future.

Lugupidamisega/With regards
Liisi Järve, haridustehnoloogia peaspetsialist

[12/04/19]   Due to a failed Moodle environment maintenance operation that took place yesterday evening, creating and performing tests may currently be disrupted. Some test questions, especially multiple choice questions may be deleted or hidden.
A notification of the disruption has been added to TalTech Moodle. We are actively working to resolve the issue and we hope to fix it latest by Thursday.

With respect,
Liisi Järve, haridustehnoloogia peaspetsialist

[11/20/19]   Q:
I had trouble with finding answers for the questions about PWM and block modulation.

A:
The directions for answers are given in the Introduction presentation https://drive.google.com/file/d/1vAZcJ1rbkIO4CpPa6Qz8I7XHwdl_aWeD/view, Slide 14, and in the Laboratory work # 4. Block modulation and 6-step modulation are the same modulation types at the 3-phase supply. "Fixed features" means the properties that cannot be changed. More information about PWM, block, and six-step modulation in power converters your may find from Introduction to Electronics, for example, https://bookboon.com/en/introduction-to-power-electronics-ebook, Section 2.3.

drive.google.com

EEV5040_Introduction.pdf

Q:
How will the exam be held?

A:
Read please in slides 2 and 4 in Moodle:

https://drive.google.com/file/d/1ufvHVMxbIhl50v81Dk2tRQtLF5iVHzcq/view

After 10th of December, ALL quizzes will be open without limitations on the number of attempts and deadlines. Everybody will find the correct answers there. It only remains to learn them. Consultations are available on request, as usual.

drive.google.com

[11/12/19]   Q:
When is the deadline for practice reports uploading?

A:
To be assessed, you have to pass successfully 4 reports before the session end. Please take into account that no plagiarism is permitted, and 2-4 corrections are usually requested after uploading. And, as usual in TTU, no service between 24.12 and 02.01.

[10/21/19]   Q:
In Quiz 5 question "Choose typical Web-handling technologies", among the correct answers should be "spicing". I found it in Internet: https://youtu.be/K_p_pfyowAM

A:
You are right. I'll correct your results. Thank you.

[10/14/19]   Q:
I do not agree with this result (A4):
"Which IP code corresponds to protection against ingress of 2.5 mm objects and sprayed water protection?" Correct answer is IP33. I answered IP44 from possible choises because IP33 is up to 2.5mm objects and spray is up to 60 degree angle (question is about what ever angle and icludes 2.5 mm objects).

A:
You are right! I'll regrade this answer.

[10/11/19]   Q:
I missed the A4 test. Is it possible to still take the test?

A:
Unfortunately, missed quizzes cannot be taken. However, all its questions and answers will be published in December.

mechamechanisms.com

mechamechanisms.com

Q:
Where can I find information about worm gears and hydraulic actuators being asked about in the last quiz?

A:
More about worm gears:
https://mechamechanisms.com/worm-drive-5a-rotating-and-translating-worm

https://www.youtube.com/watch?v=kTCqSWVO32A

https://tehnar.net.ua/en/tipyi-peredach-dlya-postupatelnogo-dvi/

https://www.ngpedia.ru/id307608p3.html

More about hydraulic actuators:
https://www.slideshare.net/Ash008/actuators-in-hydraulic-system

http://www.costudies.com/upload/L-26(SM)%20(IA&C)%20((EE)NPTEL)1476096995.pdf

https://www.hydraproducts.co.uk/blog/postid/197/hydraulic-systems-what-you-need-to-know-about-actuators.aspx

https://link.springer.com/chapter/10.1007%2F978-94-015-9427-1_4

https://www.youtube.com/watch?v=qt3WfeTdj5I

https://www.welland-tuxhorn.de/en/products/actuators/hydraulic-actuating-systems.html

https://www.hydac.com.br/wp-content/uploads/e2152-7-05-01_stellantriebe.pdf

Beside rotation the input worm also moves longitudinally owing a ...

[09/17/19]   Q:
I have a question on my quiz nr 1. In total, i have 7 correct answers out of 10, but the final grade is only 5.000/10.000. Isnt it should be 7.000/10.000? Or what is the right scale for the correct answers?

A:
As stated in the introductory presentation (EEV5040_Introduction.ppt), your quiz score is the sum of question marks. Every right answer increases your score, whereas every false one decreases it. Hence, the quiz score may vary from -0.5 to 0.5. Your result consists of seven right answers (+7), two false ones (-2), and one halfway correct and halfway wrong (0). In total +7-2+0=5 of 10 (50% of 0.5 = 0.25).

[09/17/19]   Q:
I find the answer for “What control system is more stable and temperature independent − the analogue or the digital one?” neither in the textbook nor in Internet.
A:
Thermal instability is one of the reasons why first analogue computers were quickly replaced with digital ones, analogue amplifiers – with digital ones, and analogue data-transmission channels – with pulse and digital ones.

[09/17/19]   Q:
I'm just not convinced that .dwg is the image file.
A:
I agree, it's a moot point. I’ll change it and correct your scores.

Q:
Is 5V a really standard voltage in automation?
A:
https://en.wikipedia.org/wiki/RS-232
https://en.wikipedia.org/wiki/RS-422
https://en.wikipedia.org/wiki/USB
https://en.wikipedia.org/wiki/List_of_automation_protocols

[09/17/19]   Welcome, the new members of Learndrives
Click LIKE to be involved to your new course and to follow our guidelines and notifications, state the problems, answer the questions, and share your activities with other students.

[12/20/18]   Q:
When is the ultimate deadline for reports uploading?

A:
Upload please your reports as soon as possible aiming to continue you trying to defend them by examination. Keep in mind please that, during the holidays, Moodle doesn't guaranties the service on its regular base (and neither am I).

[12/17/18]   Q:
If I would write the exam in advance in December, whether it'll be counted as one of the usually available 2 tries for an exam or is it 1 preliminary +2 examination session chances?

A:
All students are participating on an equal footing: 1 examination and 1 re-examination. In December, I made appointments for a consultation. Of course, you may use it for examination, instead of the session dates, but not as an additional chance.

[11/26/18]   Q:
I would like to ask a question about the graphs obtained in the Induction Motor Stand lab work. As you have mentioned, the nominal experimental data cannot be larger than the passport data. But how should I then understand the graph that we have obtained during the lab? Could it be that I have to read the current graph from right to
left? Thank you in advance for your help.

A:
Yes, experimental nominal data cannot exceed the passport ones. This follows from the last lecture where the mechanical, n(T), and electromechanical, n(I), characteristics were introduced. They demonstrate that starting torque and current have to be as great as possible for successful motor running. They also show that nominal point is just near the maximal speed to provide good overload capacity. These rules are common for all types of motors.

[11/19/18]   Q:
Sometimes, I cannot find explanations of my experimental results in the lecture notes. How to draw conclusions in this case?

A:
Labs help you get an experience in observation of new phenomena. This is a real way to science and to practice. If you found something unknown, you may search explanations in lectures and books. If everything is evident, no labs are needed.

Below, an example from your teammate’s conclusions is given:

“The following conclusions can be drawn from this laboratory work: 1). Fastest way to stop the motor is using DC Braking at maximal current. It is very quick, in one case it was instantaneous. DC Braking is thus a good method of stopping AC motors in case of emergencies. 2). There is a correlation between the PWM frequency and audible electrical noise. A higher frequency causes noise with a higher pitch. Although it could not be tested, a frequency above 20 kHz should thus be inaudible (range of human hearing is between 20 Hz and 20 kHz). 3). Assigning a boosting level to the motor allows for controlling the torque.”

This student has learned a lot from experimentation. Now, it’s time to find explanations in theory.

[11/18/18]   Q:
I have misunderstood the values written on the nameplate. Under current I see 1,7/1,0 A and, additionally, the nameplate includes two voltages - 230 and 400 V. Does it matter which one we take for the calculations?

A:
3-phase motor can develop one and the same power at low supply voltage/high current and at high voltage/small current. Depending on the grid voltage, an electrician chooses the method of winding connection: delta (D) or star (Y). Nameplate example: "D/Y - 230/400 V, 1.7/1.0 A". The supply voltage in our laboratory is 230 V.

[11/03/18]   Q:
Is it really worth so much emphasis on the waveforms and circuits?

A:
Waveforms and circuits serve as a language of communication for all electricians, just like the ECG is vital for all physicians or notes - for musicians. If you came to understand electricity, you have no alternative but to learn them.

502 Bad Gateway

Q:
In examination session, I have to be away of Tallinn on some urgent obstacles. May I pass the exam in another date?

A:,
The examination session for all students will take place from 2.01 until 23.01.2019. With those who passed all the labs and exercises prematurely, we may agree an examination date before Christmas. Both the laboratory and the computer class will be closed from 23.12 until the next semester (see TTU Academic calendar in Ois).

ois.ttu.ee

[09/25/18]   Q:
“Moodle fixed plagiarism”. What does it mean?

A:
The new Moodle URKUND plugin found plagiarism in your report. It means, using the common team protocol, YOU MUST REPORT INDIVIDUALLY. It concerns the title sheet, the circuit diagrams, experimental tables, all the plots, and conclusions.

[08/31/16]   Welcome, the new members of Learndrives
Click LIKE to be involved to your new course and to follow our guidelines and notifications, state the problems, answer the questions, and share your activities with other students.

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