DGVCL Exam Paper (11-12-2011) Due to skin effect 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 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 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.
DGVCL Exam Paper (11-12-2011) First zone distance relay protects the transmission line section upto 80 % of its full length Its full length 25 % of its full length 50 % of its full length 80 % of its full length Its full length 25 % of its full length 50 % of its full length 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 More than 90% 80 % 90 % Less than 90% More than 90% 80 % 90 % Less 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) If the excitation of a synchronous generator fails, it acts as a Synchronous motor Synchronous generator Induction motor Induction generator Synchronous motor Synchronous generator Induction motor Induction generator ANSWER EXPLANATION DOWNLOAD EXAMIANS APP if excitation of synchronous generator fails, operate as induction motor
DGVCL Exam Paper (11-12-2011) The corona effect can be minimized by increasing The length of the conductor Diameter of the conductor Spacing between the conductors Both spacing between the conductors and diameter of the conductor The length of the conductor Diameter of the conductor Spacing between the conductors Both spacing between the conductors and diameter of the conductor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Corona can be reduced by using large size of conductor, bundle conductor and hollow conductor.
DGVCL Exam Paper (11-12-2011) The form factor in AC means the ration of Peak value to r.m.s value R.M.S. value to average value R.M.S. value to peak value Peak value to average value Peak value to r.m.s value R.M.S. value to average value R.M.S. value to peak value Peak value to average value ANSWER DOWNLOAD EXAMIANS APP
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