DGVCL Exam Paper (11-12-2011) Reactance relay is used to protect against Earth faults only 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 ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The transient stability of a power system can be improved by Excitation control Phase shifting transformer Increasing the turbine valve opening Single pole switching of circuit breakers Excitation control Phase shifting transformer Increasing the turbine valve opening Single pole switching of circuit breakers ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) DC series motors are best suited for traction work because Its torque is proportional to the square of the armature current and speed is directional proporational to torque 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 inversely proportional to torque Torque and speed are 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 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 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) Due to skin effect Portion of the conductor near the surface carries more current and the core of the conductor carries less current 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 Current flows through the half cross section of the conductor Portion of the conductor near the surface carries more current and the core of the conductor carries less current 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 Current flows through the half cross section of 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) If the excitation of a synchronous generator fails, it acts as a Synchronous motor Induction motor Synchronous generator Induction generator Synchronous motor Induction motor Synchronous generator Induction generator ANSWER EXPLANATION DOWNLOAD EXAMIANS APP if excitation of synchronous generator fails, operate as induction motor
DGVCL Exam Paper (11-12-2011) It is difficult interrupt a capacitive current because Stored energy in the capacitor is very high It has a leading power factor Current magnitude is very small The restriking voltage can be high Stored energy in the capacitor is very high It has a leading power factor Current magnitude is very small The restriking voltage can be high ANSWER DOWNLOAD EXAMIANS APP
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