DGVCL Exam Paper (11-12-2011) The transient stability of a power system can be improved by Increasing the turbine valve opening Excitation control Single pole switching of circuit breakers Phase shifting transformer Increasing the turbine valve opening Excitation control Single pole switching of circuit breakers Phase shifting transformer ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) What happens to the contents of RAM (Random Access Memory) when the power of the computer is turned off? Content is transferred to other memory Content remains intact Content gets corrupted Content is lost Content is transferred to other memory Content remains intact Content gets corrupted Content is lost ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The efficiency of a transformer at full load, 0.8 p.f. lag is 90%. Its efficiency at full load, 0.8 p.f. lead will be 80 % 90 % Less than 90% More than 90% 80 % 90 % Less than 90% More than 90% ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Efficiency= output power/input powerefficiency = (v*i*cosφ)/((v*i*cosφ)+(x² Pc)+(Pi)) x=fractional part of full load
DGVCL Exam Paper (11-12-2011) The purpose of providing a choke in a tube light is To eliminate corona effect To improve the power factor To avoid radio interference To limit the current to an appropriate value To eliminate corona effect To improve the power factor To avoid radio interference To limit the current to an appropriate value ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which of the following power distribution system gives better reliabity ? Radial system None of these DC 3 wire system Ring main system Radial system None of these DC 3 wire system Ring main system ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Due to skin effect Portion of the conductor near the surface carries more current and the core of the conductor carries less current Uniform current flows through the conductor Portion of the conductor near the surface carries less current and the core of the conductor carries more current Current flows through the half cross section of the conductor Portion of the conductor near the surface carries more current and the core of the conductor carries less current Uniform current flows through the conductor Portion of the conductor near the surface carries less current and the core of the conductor carries more current Current flows through the half cross section of the conductor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Skin Effect:tendency of the current to crowd near the conductor surface.Skin effect is proportional to frequency, conductor diameter and permiability. Skin effect increases effective resistance of conductor.In DC, no skin effect.
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