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 less current and the core of the conductor carries more current Uniform current flows through the conductor Portion of the conductor near the surface carries more current and the core of the conductor carries less current Current flows through the half cross section of the conductor Portion of the conductor near the surface carries less current and the core of the conductor carries more current Uniform current flows through the conductor Portion of the conductor near the surface carries more current and the core of the conductor carries less 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) An IDMT relay provides An inverse time current characteristic A definite time cuttent characteristic A definite time characteristic for low values of the failt current and an inverse characteristic for high values of the fault current An inverse characteristic for low values of the fault current and a definite time characteristic for high values of the fault current An inverse time current characteristic A definite time cuttent characteristic A definite time characteristic for low values of the failt current and an inverse characteristic for high values of the fault current An inverse characteristic for low values of the fault current and a definite time characteristic for high values of the fault current ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The insulation coordination for UHV lines (above 500 kV) is done based on Switching surges Voltage level of the line Lightning and switching surges Lightning surges Switching surges Voltage level of the line Lightning and switching surges Lightning surges ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which of the following correctly represents the sequence of operations of isolator, circiut breaker and earthing switch while opening a circuit? Close earthing switch - open ciruit- breaker-open islotor Close circuit breaker-close isolator - open earthing switch Open isolator close circuit breaker-open earthing switch Open circuit breaker-open isolator-close earthing switch Close earthing switch - open ciruit- breaker-open islotor Close circuit breaker-close isolator - open earthing switch Open isolator close circuit breaker-open earthing switch Open circuit breaker-open isolator-close earthing switch 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 Ring main system DC 3 wire system Radial system None of these Ring main system DC 3 wire system 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 90 % 80 % More than 90% Less than 90% 90 % 80 % More than 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
EXAMIANS