Home » Uncategorized » GATE 2015 EE - SET 1 - Question 21

GATE 2015 EE - SET 1 - Question 21

Solution :

R_{a} = 0.152 , E_{1} = 200 V , Rate speed = N_{1} , Rate flux = \phi _{1}

Half  rated speed = N_{2} = \frac{N_{1}}{2}

Half rated flux =  \phi _{2}  ⇒  \phi _{2} = \frac{\phi _{1}}{2}

E\alpha = \phi N

\frac{E_{1}}{E_{2}} = \frac{\phi _{1}N_{1}}{\phi _{2}N_{2}}

E_{2} = 200 /4 = 50 V

E =V \left \lfloor 1 - e^\frac{-t}{RC}\right \rfloor

25 = 50 \left \lfloor 1 -e^\frac{-t}{0.1*1000*10^{-6}} \right \rfloor

\frac{1}{2}  = 1- e^\frac{-t}{100*10^{-6}}

t = 0.693 * 10 -4

t = 69.3 * 10 -6

t = 69.3μs

 

Translate »