SSC JE Electrical Engineering 2011 Paper

Question : 128 of 150

Marks: +1, -0

In the Merz Price system of protection of alternator, if

i _1

and

i _2

are the CT secondary currents, and

n_r

and

n_o

are the number of restraining coils and operating coils respectively, then the torque-balance equation is

Solution:

N_r

= number of restraining coils

N_o

= number of operating coils

I _o= I_\A -I_\B

I_r=({I_\A+I_\B}/2)

Relay operates when operating mf > restaring mµf

N_0( I_\A- I_\B)=({I_\A+I_\B}/2)N_r

N_r/N_o={I_\A+I_\B}/({I_\A+I_\B}/2)

Go to Question:

Prev Question

Next Question