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 % Less than 90% 90 % More than 90% 80 % Less than 90% 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 main criterion for the design of a distributor is Temperature rise Corona loss Radio interference Voltage drop Temperature rise Corona loss Radio interference Voltage drop ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which lightning stroke is most dangerous? Direct stroke on line conductor Direct stroke on ground wire Indirect stroke on conductor Direct stoke on tower top Direct stroke on line conductor Direct stroke on ground wire Indirect stroke on conductor Direct stoke on tower top ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Transposition of transmission line is done to Reduce skin effect Balance line voltage drop Reduce corona Reduce line loss Reduce skin effect Balance line voltage drop Reduce corona Reduce line loss ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Magnetizing inrush current Lightning Switching over voltages Unbalanced protection Magnetizing inrush current Lightning Switching over voltages Unbalanced protection 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) In a power plant, a reserve generating capacity which is not in service but is in operation is known as Cold reserve Hot reserve Spinning reserve Firm power Cold reserve Hot reserve Spinning reserve Firm power ANSWER DOWNLOAD EXAMIANS APP
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