DGVCL Exam Paper (11-12-2011) The bus bar zone faults are generally Three phase short ciruits Phase to phase faults Single line to ground faults Double line to ground faults Three phase short ciruits Phase to phase faults Single line to ground faults Double line to ground faults 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) The main criterion for the design of a distributor is Corona loss Temperature rise Radio interference Voltage drop Corona loss Temperature rise Radio interference Voltage drop ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Magnetizing inrush current Unbalanced protection Lightning Switching over voltages Magnetizing inrush current Unbalanced protection Lightning Switching over voltages 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) Due to skin effect 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 Current flows through the half cross section of the conductor Portion of the conductor near the surface carries more current and the core of the conductor carries less current 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 Current flows through the half cross section of the conductor Portion of the conductor near the surface carries more current and the core of the conductor carries less current 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) It is difficult interrupt a capacitive current because The restriking voltage can be high Current magnitude is very small Stored energy in the capacitor is very high It has a leading power factor The restriking voltage can be high Current magnitude is very small Stored energy in the capacitor is very high It has a leading power factor ANSWER DOWNLOAD EXAMIANS APP
EXAMIANS