DGVCL Exam Paper (11-12-2011) Under operating conditions, the secondary of a current transformer is always short ciruited because It protects the secondary ciruits It protects the primary ciruits It avoids core saturation and high voltage induction It is safe to human beings It protects the secondary ciruits It protects the primary ciruits It avoids core saturation and high voltage induction It is safe to human beings ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Permittivity is expressed in terms of Farad/m N/m Weber /m farad/sq. m. Farad/m N/m Weber /m farad/sq. m. ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) If the fault current is 2000 A, the relay plug setting is 50% and the CT ratio is 400/5, the plug setting multiple will be 15 10 50 25 15 10 50 25 ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) An over excited synchronous motor draws current at Depends on nature of load Leading power factor Unity power factor Lagging power factor Depends on nature of load Leading power factor Unity power factor Lagging power factor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Over excitation : leading currentUnder excitation : lagging currentNormal excitation : current with unity PF (in phase current)
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 Current flows through the half cross section of the conductor Portion of the conductor near the surface carries less current and the core of the conductor carries more current Uniform current flows through the conductor 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 Portion of the conductor near the surface carries less current and the core of the conductor carries more current 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) A 3 phase, 6 pole induction motor operates on 440 V, 50 Hz, supply. If the actual speed of the motor is 960 rpm the slip will be 5 % 0.4 % 6 % 4 % 5 % 0.4 % 6 % 4 % ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Ns = 120f/PSlip=(Ns-Nr)/NsNs = 1000 and Nr = 960 from equation of slip, S = (1000-960)/1000S = 0.04 or 4%
EXAMIANS