DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Unbalanced protection Switching over voltages Magnetizing inrush current Lightning Unbalanced protection Switching over voltages Magnetizing inrush current Lightning 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) The bus bar zone faults are generally Single line to ground faults Double line to ground faults Phase to phase faults Three phase short ciruits Single line to ground faults Double line to ground faults Phase to phase faults Three phase short ciruits ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The advantage of slipring induction motor over the squirrel cage induction motor is It is suitable for higher speeds It has a higher efficiency It's power factor is higher It can be started with the help of rotor resistances It is suitable for higher speeds It has a higher efficiency It's power factor is higher It can be started with the help of rotor resistances ANSWER EXPLANATION DOWNLOAD EXAMIANS APP slip ring motor have high starting torque compare to squirrel cage motor and have good speed controlalso have high over loading capacity, smooth acceleration under heavy loads.
DGVCL Exam Paper (11-12-2011) Different computers are connected to a LAN by a cable and a Special wires Telephone line Interface card Modem Special wires Telephone line Interface card Modem ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The efficiency of a transformer at full load, 0.8 p.f. lag is 90%. Its efficiency at full load, 0.8 p.f. lead will be More than 90% 90 % Less than 90% 80 % More than 90% 90 % Less than 90% 80 % ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Efficiency= output power/input powerefficiency = (v*i*cosφ)/((v*i*cosφ)+(x² Pc)+(Pi)) x=fractional part of full load
DGVCL Exam Paper (11-12-2011) If a 5 A fuse is blown frequently in a house lighting circuit, it is required to Insert a fuse of higher voltage rating Check the load Reduce the load Insert a fuse of higher current rating Insert a fuse of higher voltage rating Check the load Reduce the load Insert a fuse of higher current rating ANSWER DOWNLOAD EXAMIANS APP
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