Bissoy.com
Doctors Medicines MCQs Q&A

Why brushes shifting method is not employed in practical commutation?

Why brushes shifting method is not employed in practical commutation? Correct Answer Causes demagnetization

Brushes are located at GNA’s, a small voltage is induced in the commutating coil. It opposes current commutation as the commutating coil is cutting the flux which has the same sign as that of the pole being left behind. It could be partially remedied by shifting the brushes towards MNA but that causes direct demagnetization and is therefore not employed in practice.

Related Questions

The ratio of paints and brushes in a shop is 5 : 16 respectively. The average number of paints and brushes is 840. What is the 40% of number of brushes in the shop?
Three statements are given, followed by three conclusions numbered I, II and III. Assuming the statements to be true, even if they seem to be at variance with commonly known facts, decide which of the conclusion logically follow(s) from the statements. Statements: All threads are needles. Some needles are brushes. All needles are cupboards. Conclusions: I. Some brushes are cupboards. II. All threads are cupboards. III. All brushes are threads.
In this question, two statements are given followed by two conclusions. Choose the conclusion(s) which best fit(s) logically. Statements: 1) All colours are pants. 2) All pants are brushes. Conclusions: I. Some brushes are pants. II. Some brushes are colours.
If in the DC machine, the reversal of current in the coil is faster than ideal or linear commutation then the commutation is said to be __________ commutation.
"Which among the following is / are correct statements with respect to Shifting Cultivation as practiced in India?
1. India's largest area under shifting cultivation is in the state of Arunachal Pradesh.
2. In recent years, the cycle of shifting cultivation on a particular land has reduced drastically.
Select the correct option from given below:"
If the critical commutation time is 2 ms but it was observed that the practical commutation took 2.5 ms. This is the case of __________
Mr. Justin wanted to test his students' understanding of the 'nature of weekly markets from a seller's point of view'. Which of the following questions are suited to test this? i. Can a weekly market address all the needs of a family? Why or why not? ii. Compare and contrast the characteristics of a weekly market and a permanent shop. iii. Are you likely to find a well-known brand as part of a weekly market? Why or why not? iv. Can any seller increase their price a lot compared to other sellers in a weekly market? Why or why not?
The question given below is in the form of a statement followed by assumptions 1 and 2. You may assume that everything said in the statement is true, then consider the two assumptions and decide which of them, beyond a reasonable doubt, logically follows from the statement. Statement: Students who have not submitted the record book will not be allowed to appear in the practical examination. Assumption: 1. Practical exams make students technically strong in the subject 2. Record Book is mandatory for appearing in the practical examination.
In the question below a statement is given followed by two assumptions 1 and 2. You have to assume everything in the statement to be true and then consider the two assumptions and decide which of them logically follows from the information given in the statement beyond any considerable doubt. Statement:  Students who do not present the record book will not be allowed to appear in the practical examination. Assumption: 1. Record book is mandatory for appearing in the practical examination. 2. Practical exam makes a student technically strong in a subject.
For an examination of a practical based subject, the total marks is 100. The break-up for theory, practical, project and viva voce is 40%, 30%, 20%, 10%. A candidate scored 80% in theory, 70% in practical, 60% in project and 50% in viva voce. What was her aggregate percentage?