Which of the following is true, considering the rotor of a three-phase induction motor in the blocked state?

This question was previously asked in
MPPGCL JE Electrical 28 April 2023 Shift 1 Official Paper
View all MPPGCL Junior Engineer Papers >
  1. Supply frequency > Rotor frequency
  2. Supply frequency = Rotor frequency 
  3. Supply frequency < Rotor frequency
  4. Rotor frequency = 0 (Always)

Answer (Detailed Solution Below)

Option 2 : Supply frequency = Rotor frequency 
Free
MPPGCL JE Electrical Full Test 1
3.9 K Users
100 Questions 100 Marks 120 Mins

Detailed Solution

Download Solution PDF

Concept

The slip of an induction motor is given by:

\(s={N_s-N_r\over N_s}\)

where, Ns = Synchronous speed

Nr = Rotor speed 

Explanation

The rotor frequency of a 3ϕ induction motor is given by:

\(f_r=sf_s\)

When the rotor of a three-phase induction motor is in the blocked state (not rotating), the rotor speed, i.e. Nr = 0

\(s={N_s-0\over N_s}\)

s = 1

The rotor induced frequency is:

\(f_r=1\times f_s\)

\(f_r=f_s\)

Supply frequency = Rotor frequency 

Latest MPPGCL Junior Engineer Updates

Last updated on May 29, 2025

-> MPPGCL Junior Engineer result PDF has been released at the offiical website.

-> The MPPGCL Junior Engineer Exam Date has been announced.

-> The MPPGCL Junior Engineer Notification was released for 284 vacancies.

-> Candidates can apply online from 23rd December 2024 to 24th January 2025.

-> The selection process includes a Computer Based Test and Document Verification.

-> Candidates can check the MPPGCL JE Previous Year Papers which helps to understand the difficulty level of the exam.

Get Free Access Now
Hot Links: teen patti casino download teen patti rich teen patti sweet teen patti baaz