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 % More than 90% 80 % Less than 90% 90 % More than 90% 80 % 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) 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) In the protection of transformers, harmonic restraint is used to guard against Switching over voltages Unbalanced protection Magnetizing inrush current Lightning Switching over voltages Unbalanced protection Magnetizing inrush current Lightning ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Initial inrush of magnetizing currents have high component of even and odd harmonics.2nd - 63%3rd -26.8%4th- 5.1%5th- 4.1%6th- 3.77th-2.4
DGVCL Exam Paper (11-12-2011) Transposition of transmission line is done to Reduce corona Reduce line loss Reduce skin effect Balance line voltage drop Reduce corona Reduce line loss Reduce skin effect Balance line voltage drop 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 lost Content gets corrupted Content is transferred to other memory Content remains intact Content is lost Content gets corrupted Content is transferred to other memory Content remains intact ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The bus bar zone faults are generally Single line to ground faults Double line to ground faults Three phase short ciruits Phase to phase faults Single line to ground faults Double line to ground faults Three phase short ciruits Phase to phase faults ANSWER DOWNLOAD EXAMIANS APP
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