DGVCL Exam Paper (11-12-2011) The transient stability of a power system can be improved by Single pole switching of circuit breakers Excitation control Increasing the turbine valve opening Phase shifting transformer Single pole switching of circuit breakers Excitation control Increasing the turbine valve opening Phase shifting transformer 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 80 % Less than 90% More than 90% 90 % 80 % Less than 90% More than 90% 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 motor is used to start heavy loads? Shunt motor Differentially compounded motor Cumulatively compounded motor Series motor Shunt motor Differentially compounded motor Cumulatively compounded motor Series motor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Torque in d.c motor = k* φ * IaIn series motor φ α IaTα I²starting torque of dc series motor is high
DGVCL Exam Paper (11-12-2011) The bus bar zone faults are generally Double line to ground faults Three phase short ciruits Single line to ground faults Phase to phase faults Double line to ground faults Three phase short ciruits Single line to ground faults Phase to phase faults ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The positive and negative sequence impedance of a transmission line are Different Zero Infinite Equal Different Zero Infinite Equal ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) A fuse wire should have Low specific resistance and low melting point High specific resistance and high melting point High specific resistance and low melting point Low specific resistance and high melting point Low specific resistance and low melting point High specific resistance and high melting point High specific resistance and low melting point Low specific resistance and high melting point ANSWER DOWNLOAD EXAMIANS APP
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