DGVCL Exam Paper (11-12-2011) The purpose of interpoles in DC machines is to nullify The reactance voltage The cross-magnetizing effect of armature mmf Both the cross-magnetizing mmf and the reactance voltage The demagnetizing effect of armature mmf The reactance voltage The cross-magnetizing effect of armature mmf Both the cross-magnetizing mmf and the reactance voltage The demagnetizing effect of armature mmf 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) Which lightning stroke is most dangerous? Direct stoke on tower top 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 ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The transient stability of a power system can be improved by Increasing the turbine valve opening Phase shifting transformer Single pole switching of circuit breakers Excitation control Increasing the turbine valve opening Phase shifting transformer Single pole switching of circuit breakers Excitation control ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) DC series motors are best suited for traction work because Torque and speed are inversely proportional to the square of the armature current Its torque is proportional to the square of the armature current and speed is directional proporational to torque Its torque is proportional to the square of the armature current and speed is inversely proportional to torque Torque and speed are proportional to the square of the armature current Torque and speed are inversely proportional to the square of the armature current Its torque is proportional to the square of the armature current and speed is directional proporational to torque Its torque is proportional to the square of the armature current and speed is inversely proportional to torque Torque and speed are proportional to the square of the armature current ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Torque in d.c motor = k* φ * IaIn series motor φ α IaTα I²N α 1/φN α 1/T
DGVCL Exam Paper (11-12-2011) Bulk power transmission over long HVDC lines are preferred on account of Low cost of HVDC terminals Simple protection Minimum line power losses No harmonic problems Low cost of HVDC terminals Simple protection Minimum line power losses No harmonic problems ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Reactance relay is used to protect against Both phase and earth faults Over voltage faults Phase faults only Earth faults only Both phase and earth faults Over voltage faults Phase faults only Earth faults only ANSWER DOWNLOAD EXAMIANS APP
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