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 % 4 % 0.4 % 6 % 5 % 4 % 0.4 % 6 % 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%
DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Switching over voltages Unbalanced protection Magnetizing inrush current Lightning Switching over voltages Unbalanced protection Magnetizing inrush current Lightning 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) Fot fast load flow calculations, the best method is Newton-Raphson Gauss-Siedal De-coupled method Approximate method Newton-Raphson Gauss-Siedal De-coupled method Approximate method ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which lightning stroke is most dangerous? Indirect stroke on conductor Direct stroke on ground wire Direct stoke on tower top Direct stroke on line conductor Indirect stroke on conductor Direct stroke on ground wire Direct stoke on tower top Direct stroke on line conductor ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The purpose of providing a choke in a tube light is To improve the power factor To eliminate corona effect To avoid radio interference To limit the current to an appropriate value To improve the power factor To eliminate corona effect To avoid radio interference To limit the current to an appropriate value ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Hysteresis in an instrument means The change in the same reading when the input is first increased and then decreased The repeatability of the instrument The inaccuracy due to change in temperature The reliability of the instrument The change in the same reading when the input is first increased and then decreased The repeatability of the instrument The inaccuracy due to change in temperature The reliability of the instrument ANSWER DOWNLOAD EXAMIANS APP
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