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 6 % 0.4 % 4 % 5 % 6 % 0.4 % 4 % 5 % 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 Magnetizing inrush current Lightning Switching over voltages Unbalanced protection Magnetizing inrush current Lightning Switching over voltages Unbalanced protection 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) Ybus used in power flow studies and Zbus used in short circuit studies Are the same Have no inter relation Are transpose of each other Are inverse of each other Are the same Have no inter relation Are transpose of each other Are inverse of each other ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) A device connected to the computer which converts digital signals to analog and vice-versa is Keyboard Modem CPU UPS Keyboard Modem CPU UPS ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The transient stability of a power system can be improved by 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 Increasing the turbine valve opening ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The purpose of providing a choke in a tube light is 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 To improve the power factor To eliminate corona effect ANSWER DOWNLOAD EXAMIANS APP
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