DGVCL Exam Paper (11-12-2011) The corona effect can be minimized by increasing Spacing between the conductors Diameter of the conductor The length of the conductor Both spacing between the conductors and diameter of the conductor Spacing between the conductors Diameter of the conductor The length of the conductor Both spacing between the conductors and diameter of the conductor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Corona can be reduced by using large size of conductor, bundle conductor and hollow conductor.
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 50 MVA 20 MVA 10 MVA 60 MVA 50 MVA 20 MVA 10 MVA 60 MVA ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Short circuit kVA = Base kVA/%X
DGVCL Exam Paper (11-12-2011) Due to skin effect Portion of the conductor near the surface carries more current and the core of the conductor carries less current Current flows through the half cross section of the conductor Portion of the conductor near the surface carries less current and the core of the conductor carries more current Uniform current flows through the conductor Portion of the conductor near the surface carries more current and the core of the conductor carries less current Current flows through the half cross section of the conductor Portion of the conductor near the surface carries less current and the core of the conductor carries more current Uniform current flows through the conductor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Skin Effect:tendency of the current to crowd near the conductor surface.Skin effect is proportional to frequency, conductor diameter and permiability. Skin effect increases effective resistance of conductor.In DC, no skin effect.
DGVCL Exam Paper (11-12-2011) An AC series circuit has R = 6 Ω, XL = 20 Ω and Xc = 12 Ω. The ciruit power factor will be 0.6 lagging 0.5 leading 0.8 lagging 0.6 leading 0.6 lagging 0.5 leading 0.8 lagging 0.6 leading ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The insulation coordination for UHV lines (above 500 kV) is done based on Lightning surges Lightning and switching surges Voltage level of the line Switching surges Lightning surges Lightning and switching surges Voltage level of the line Switching surges 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)
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