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% 90 % 80 % Less than 90% More than 90% 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) A fixed step by step procedure for finding the solution of a problem on computer is called Software Hardware Algorithm Logic Software Hardware Algorithm Logic ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Due to skin effect Portion of the conductor near the surface carries less current and the core of the conductor carries more current 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 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 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 Uniform current flows through the conductor 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) In carrier current protection, the purpose of the wave trap is for All of these Trapping high frequency waves entering into generator/transformer unit. Trapping power frequency waves Tripping fault current All of these Trapping high frequency waves entering into generator/transformer unit. Trapping power frequency waves Tripping fault current ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which of the following power distribution system gives better reliabity ? Ring main system None of these DC 3 wire system Radial system Ring main system None of these DC 3 wire system Radial system ANSWER DOWNLOAD EXAMIANS APP
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? Positive cycle of sine wave DC Negative cycle of sine wave AC Positive cycle of sine wave DC Negative cycle of sine wave AC ANSWER DOWNLOAD EXAMIANS APP
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