Electrical Machines What is the necessity of copper brushes in a dc motors? To convert alternating supply current to direct current. To absorb the mechanical shocks produced during running condition. To increase the flux cutting by the rotor. None of these. To convert alternating supply current to direct current. To absorb the mechanical shocks produced during running condition. To increase the flux cutting by the rotor. None of these. 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 generator 2 gets over load 200 MW and 400MW None of these generator 1 gets over load generator 2 gets over load 200 MW and 400MW None of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The external resistance to be added in the armature circuit to limit the armature current to 125% of its rated value is 15.9 Ω 15.1 Ω 31.1 Ω 31.9 Ω 15.9 Ω 15.1 Ω 31.1 Ω 31.9 Ω ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The teeth in the armature of a DC machines are sometimes skewed. This is done to reduce eddy electric current loss. hysteresis loss. copper loss. vibrations. eddy electric current loss. hysteresis loss. copper loss. vibrations. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines In Ward-Leonard system, the lower limit of the speed imposed by None of above. Armature resistance. Field resistance. Residual magnetism of the generator. None of above. Armature resistance. Field resistance. Residual magnetism of the generator. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.25 p.u 0.75 p.u 0.125 p.u 0.5 p.u 0.25 p.u 0.75 p.u 0.125 p.u 0.5 p.u ANSWER DOWNLOAD EXAMIANS APP
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