DGVCL Exam Paper (11-12-2011) All the peripheral devices connected to a computer require power to work. Which of the following voltages is required for the motherboard to work? AC Negative cycle of sine wave DC Positive cycle of sine wave AC Negative cycle of sine wave DC Positive cycle of sine wave ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) If the excitation of a synchronous generator fails, it acts as a Induction motor Synchronous generator Synchronous motor Induction generator Induction motor Synchronous generator Synchronous motor Induction generator ANSWER EXPLANATION DOWNLOAD EXAMIANS APP if excitation of synchronous generator fails, operate as induction motor
DGVCL Exam Paper (11-12-2011) Which lightning stroke is most dangerous? Indirect stroke on conductor Direct stroke on line conductor Direct stroke on ground wire Direct stoke on tower top Indirect stroke on conductor Direct stroke on line conductor Direct stroke on ground wire Direct stoke on tower top 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 % Less than 90% More than 90% 90 % 80 % 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) An over excited synchronous motor draws current at Unity power factor Lagging power factor Depends on nature of load Leading power factor Unity power factor Lagging power factor Depends on nature of load Leading power factor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Over excitation : leading currentUnder excitation : lagging currentNormal excitation : current with unity PF (in phase current)
DGVCL Exam Paper (11-12-2011) The circuit breaker generally used in railway traction is Bulk Oil CB Air break CB Vacuum CB Minimum Oil CB Bulk Oil CB Air break CB Vacuum CB Minimum Oil CB ANSWER DOWNLOAD EXAMIANS APP
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