Question
Download Solution PDFA 6 pole, 50 Hz, 1-phase Induction Motor runs at a speed of 900 rpm. The frequency of currents in the cage rotor will be -
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
The synchronous speed is given by
Where,
f is the supply frequency in Hz or C/s
P is the number of poles
The induction motor rotates at a speed (Nr) close but less than the synchronous speed.
Slip of an induction motor is given by,
Where,
Ns is the synchronous speed
and Nr is the rotor speed
Rotor current frequency for forward slip (fr) = sf
Rotor current frequency for backward slip (fr') = (2 - s) f
The slip is negative when the rotor speed is more than the synchronous speed of the rotor field and is in the same direction.
Calculation:
Given -
Number of poles (P) = 6
Frequency (f) = 50 Hz
Speed of the induction motor, Nr = 900 rpm
Speed of the rotating magnetic field is,
Slip,
The two rotor current frequencies are
Last updated on May 12, 2025
-> RSMSSB JE Answer Key 2025 has been released on 12th May, 2025 at the official website.
-> Candidates can raise objections against the RSMSSB JE Response Sheet from 17th May to 19th May, 2025.
-> The RSMSSB JE Vacancies have been revised. A total, 1355 vacancies are announced for Junior Engineer post in various departments.
-> The exam was held on 6th, 7th, 8th, 10th, 11th, and 22nd of February 2025.
-> RSMSSB Junior Engineer 2025 Notification has been released for 1226 vacancies.
-> Candidates can apply for the said post by 27th December 2024.
-> The RSMSSB Junior Engineer exam is conducted by the Rajasthan Subordinate and Ministerial Services Selection Board to recruit candidates for engineering roles in various departments.
-> The finally appointed candidates will be entitled to Pay Matrix Level 10.
-> Prepare for the exam with RSMSSB JE Previous Year Papers.