Ask a Question
  • Home
  • Electric Drives
  • A 20-pole, 3-phase, 90 Hz induction motor is operating at a speed of _______ rpm. The frequency of...

A 20-pole, 3-phase, 90 Hz induction motor is operating at a speed of _______ rpm. The frequency of the rotor current of the motor in Hz is 20.

← Prev Question Next Question →
+1 vote
196 views
in Electric Drives by (99.8k points)
A 20-pole, 3-phase, 90 Hz induction motor is operating at a speed of  _______ rpm. The frequency of the rotor current of the motor in Hz is 20.

(a) 418.56

(b) 420.12

(c) 421.23

(d) 422.45

I had been asked this question during an online interview.

My query is from Induction Motors Speed Control topic in chapter Speed Control of Direct Current Motors & Induction Motors of Electric Drives

1 Answer

+2 votes
by (1.2m points)
selected by
 
Best answer
The correct answer is (b) 420.12

Explanation: Given a number of poles = 20. Supply frequency is 90 Hz. Ns=120×f÷P=120×90÷20 = 540 rpm. S=20÷90 = .222 Hz. Nr=(1-s)Ns = 420.12 rpm. Rotor speed is 420.12 rpm.

Related questions

Welcome to TalkJarvis QnA, a question-answer community website for the people by the people. On TalkJarvis QnA you can ask your doubts, curiosity, questions and whatever going in your mind either related to studies or others. Experts and people from different fields will answer.

Most popular tags

biology – class 12 biology – class 11 construction & building materials chemistry – class 12 electronic devices & circuits network theory data structures & algorithms ii cell biology ic engine insurance finance money computational fluid dynamics engineering physics i discrete mathematics chemistry – class 11 aerodynamics casting-forming-welding i engineering mathematics operating system casting-forming-welding ii engineering drawing mysql engineering geology digital circuits wireless mobile energy management electrical measurements digital communications cyber security analytical instrumentation embedded systems electric drives cytogenetics advanced machining computer fundamentals life sciences basic civil engineering iot design of electrical machines physics – class 12 applied chemistry dairy engineering basic chemical engineering cloud computing microprocessor bioinformatics aircraft design aircraft maintenance software engineering drug biotechnology digital signal processing biochemistry data structures & algorithms i automotive engine design avionics engineering material & metallurgy energy engineering cognitive radio unix electrical machines biomedical instrumentation object oriented programming electromagnetic theory power electronics analog communications bioprocess engineering civil engineering drawing engineering metrology physics – class 11 mathematics – class 12 engineering chemistry i basic electrical engineering unit processes mongodb signals and systems cryptograph & network security hadoop mathematics – class 11 engineering physics ii html control systems engineering mechanics antennas analog circuits computer network java sql server javascript concrete technology chemical process calculation artificial intelligence design of steel structures c++ database management computer architecture engineering chemistry ii corrosion engineering chemical technology dc machines
Powered by TalkJarvis
...