DGVCL Exam Paper (11-12-2011) If the excitation of a synchronous generator fails, it acts as a Induction motor Synchronous generator Synchronous motor Induction generator Induction motor Synchronous generator Synchronous motor Induction generator ANSWER EXPLANATION DOWNLOAD EXAMIANS APP if excitation of synchronous generator fails, operate as induction motor
DGVCL Exam Paper (11-12-2011) An over excited synchronous motor draws current at Lagging power factor Depends on nature of load Unity power factor Leading power factor Lagging power factor Depends on nature of load Unity power factor Leading 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) 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 4 % 5 % 6 % 0.4 % 4 % 5 % 6 % 0.4 % 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%
DGVCL Exam Paper (11-12-2011) Which of the following power distribution system gives better reliabity ? Radial system Ring main system None of these DC 3 wire system Radial system Ring main system None of these DC 3 wire system ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) First zone distance relay protects the transmission line section upto 50 % of its full length Its full length 80 % of its full length 25 % of its full length 50 % of its full length Its full length 80 % of its full length 25 % of its full length ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The purpose of interpoles in DC machines is to nullify 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 The demagnetizing effect of armature mmf 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
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