DGVCL Exam Paper (11-12-2011) If the percentage reactance of the system upto the point of fault is 20% and the base kVA is 10,000 the short ciruit kVA is 60 MVA 10 MVA 50 MVA 20 MVA 60 MVA 10 MVA 50 MVA 20 MVA ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Short circuit kVA = Base kVA/%X
DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Switching over voltages Lightning Unbalanced protection Magnetizing inrush current Switching over voltages Lightning Unbalanced protection Magnetizing inrush current 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) In a series RLC circuit at resonance Current is minimum and power factor is unity Current is minimum and power factor is 0.5 Current is maximum and power factor is 0.5 Current is maximum and power factor is unity Current is minimum and power factor is unity Current is minimum and power factor is 0.5 Current is maximum and power factor is 0.5 Current is maximum and power factor is unity ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Bulk power transmission over long HVDC lines are preferred on account of Low cost of HVDC terminals Simple protection Minimum line power losses No harmonic problems Low cost of HVDC terminals Simple protection Minimum line power losses No harmonic problems ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) An over excited synchronous motor draws current at 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 Lagging 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) The main criterion for the design of a distributor is Corona loss Radio interference Voltage drop Temperature rise Corona loss Radio interference Voltage drop Temperature rise ANSWER DOWNLOAD EXAMIANS APP
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