DGVCL Exam Paper (11-12-2011) The corona effect can be minimized by increasing The length of the conductor Spacing between the conductors Diameter of the conductor Both spacing between the conductors and diameter of the conductor The length of the conductor Spacing between the conductors Diameter 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) Due to skin effect Portion of the conductor near the surface carries less current and the core of the conductor carries more current 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 Uniform current flows through the conductor Portion of the conductor near the surface carries less current and the core of the conductor carries more current 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 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) 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 20 MVA 50 MVA 60 MVA 10 MVA 20 MVA 50 MVA 60 MVA 10 MVA ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Short circuit kVA = Base kVA/%X
DGVCL Exam Paper (11-12-2011) The mutual inductance between two unity coupled coils of 9 H and 4 H is 13 H 36 H 6 H 2.2 H 13 H 36 H 6 H 2.2 H ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which motor is used to start heavy loads? Cumulatively compounded motor Series motor Shunt motor Differentially compounded motor Cumulatively compounded motor Series motor Shunt motor Differentially compounded motor ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Torque in d.c motor = k* φ * IaIn series motor φ α IaTα I²starting torque of dc series motor is high
DGVCL Exam Paper (11-12-2011) Rated making capacity of a ciruit breaker is equal to √2 X rated symmetrical breaking capacity 1.11 X rated symmetrical breaking capacity 2.55 X rated symmetrical breaking capacity Rated symmetrical breaking capacity √2 X rated symmetrical breaking capacity 1.11 X rated symmetrical breaking capacity 2.55 X rated symmetrical breaking capacity Rated symmetrical breaking capacity ANSWER DOWNLOAD EXAMIANS APP
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