Electrical Machines
To have sparkless commutation, the armature reaction effect in a DC machine is neutralized by

 shifting the brush axis from GNA to MNA.
 fixing the brush axis inline with the pole axis.
 increasing field excitation.
  compensating winding and commutating poles.

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
Two synchronous generators operating in parallel 200 MW and 400 MW respectively. The drooping characteristics of their governors are 4% and 5% from no load to full load. Consider the governors operating at 50Hz on no load. How will the machine share, if the load is 600 MW?

 generator 1 gets over load
None of these
 generator 2 gets over load
 200 MW and 400MW

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
A compound dc generator is delivering full load current at a terminal voltage of 230 V. Its series-field winding gets short circuited. If its terminal voltage 1. becomes more than 230 V, it is overcompounded generator 2. becomes more than 230 V, it is differentially compounded generator 3. becomes less than 230 V, it is overcompounded generator 4. becomes less than 230 V, it is differentially compounded generator 5. becomes less than 230 V, it is level compounded generator From these, the correct answer is

 1, 4
 2,3
 1, 4, 5
 2, 3, 5

ANSWER DOWNLOAD EXAMIANS APP

Electrical Machines
With the increase in speed of a DC motor

 back emf falls and line current increases.
 back emf increases but line current falls.
 both back emf as well as line current fall.
 both back emf as well as line current increase.

ANSWER DOWNLOAD EXAMIANS APP
MORE MCQ ON Electrical Machines