Question
Download Solution PDFA 220V dc machine supplies 20A at 200 V as a generator. The armature resistance is 0.2 . If the machine is now operated as a motor as a same terminal voltage and current but with flux increased by 10%, the ratio of motor speed to generator speed is
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFConcept:
The EMF equation of a DC Machine is
From the above equation,
In a dc generator, induced emf is
Eg = V + IaRa
In a dc motor, back emf is
Eb = V – IaRa
Where,
N is the speed in rpm
ϕ is the flux per pole
P is the number of poles
Z is the number of conductors
V is the terminal voltage
Ia is the armature current
Ra is the armature resistance
Calculation:
Given-
V = 200, Ra = 0.2 Ω, Ia = 20 A, ϕ2 = 1.1 ϕ1
Let ϕ1 = Generator flux, ϕ2 = Motor flux, N1 = Generator speed, N2 = Motor speed
∴
Last updated on May 28, 2025
-> ISRO Technician recruitment notification 2025 has been released.
-> Candidates can apply for the ISRO recruitment 2025 for Technicians from June 2.
-> A total of 64 vacancies are announced for the recruitment of Technician.
-> The selection of the candidates is based on their performance in the Written Exam and Skill Test.
-> Candidates who want a successful selection must refer to the ISRO Technician Previous Year Papers to increase their chances of selection for the Technician post.