DGVCL Exam Paper (11-12-2011) The bus bar zone faults are generally Single line to ground faults Phase to phase faults Double line to ground faults Three phase short ciruits Single line to ground faults Phase to phase faults Double line to ground faults Three phase short ciruits ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The purpose of interpoles in DC machines is to nullify The demagnetizing effect of armature mmf The cross-magnetizing effect of armature mmf The reactance voltage Both the cross-magnetizing mmf and the reactance voltage The demagnetizing effect of armature mmf The cross-magnetizing effect of armature mmf The reactance voltage Both the cross-magnetizing mmf and the reactance voltage 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) 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 0.4 % 6 % 4 % 5 % 0.4 % 6 % 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) If the dielectric strength of the medium between the contacts builds up more rapidly than the restriking voltage the arc will Decrease in size Restrike Increase in size Extinguish Decrease in size Restrike Increase in size Extinguish ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Unbalanced protection Switching over voltages Magnetizing inrush current Lightning Unbalanced protection Switching over voltages 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) The purpose of providing a choke in a tube light is To improve the power factor To eliminate corona effect To limit the current to an appropriate value To avoid radio interference To improve the power factor To eliminate corona effect To limit the current to an appropriate value To avoid radio interference ANSWER DOWNLOAD EXAMIANS APP
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