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 % 5 % 4 % 0.4 % 6 % 5 % 4 % 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 type of back up protection is widely used for the protection of transmission lines? Breaker backup Relay backup Control backup Remote backup Breaker backup Relay backup Control backup Remote backup ANSWER DOWNLOAD EXAMIANS APP
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 inverse of each other Are transpose of each other Are the same Have no inter relation Are inverse of each other Are transpose of each other ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) In a power plant, a reserve generating capacity which is not in service but is in operation is known as Hot reserve Firm power Spinning reserve Cold reserve Hot reserve Firm power Spinning reserve Cold reserve ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) An over excited synchronous motor draws current at Lagging power factor Leading power factor Depends on nature of load Unity power factor Lagging power factor Leading power factor Depends on nature of load Unity 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) Hysteresis in an instrument means The change in the same reading when the input is first increased and then decreased The inaccuracy due to change in temperature The reliability of the instrument The repeatability of the instrument The change in the same reading when the input is first increased and then decreased The inaccuracy due to change in temperature The reliability of the instrument The repeatability of the instrument ANSWER DOWNLOAD EXAMIANS APP
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