DGVCL Exam Paper (11-12-2011) The transient stability of a power system can be improved by Single pole switching of circuit breakers Increasing the turbine valve opening Phase shifting transformer Excitation control Single pole switching of circuit breakers Increasing the turbine valve opening Phase shifting transformer Excitation control ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The purpose of interpoles in DC machines is to nullify The reactance voltage The demagnetizing effect of armature mmf The cross-magnetizing effect of armature mmf Both the cross-magnetizing mmf and the reactance voltage The reactance voltage The demagnetizing effect of armature mmf The cross-magnetizing effect of armature mmf Both the cross-magnetizing mmf and the reactance voltage ANSWER EXPLANATION DOWNLOAD EXAMIANS APP interpoles is widely use to improve commutationplace between main poles fitted to yokefunctions:to neutralize armature mmf in commutating zoneto produce some flux in commutating zone
DGVCL Exam Paper (11-12-2011) Ybus used in power flow studies and Zbus used in short circuit studies Are inverse of each other Are transpose of each other Have no inter relation Are the same Are inverse of each other Are transpose of each other Have no inter relation Are the same ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which motor is used to start heavy loads? Series motor Shunt motor Cumulatively compounded motor Differentially compounded motor Series motor Shunt motor Cumulatively compounded motor Differentially compounded 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) In the protection of transformers, harmonic restraint is used to guard against Lightning Magnetizing inrush current Unbalanced protection Switching over voltages Lightning Magnetizing inrush current Unbalanced protection Switching over voltages 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) If the voltage at the two ends of a line are 132 kV, and its reactance is 40 Ω, the stability limit of the line is 251.5 MW 435.6 MW 500 MW 217.8 MW 251.5 MW 435.6 MW 500 MW 217.8 MW ANSWER DOWNLOAD EXAMIANS APP
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