DGVCL Exam Paper (11-12-2011) The form factor in AC means the ration of R.M.S. value to peak value Peak value to r.m.s value Peak value to average value R.M.S. value to average value R.M.S. value to peak value Peak value to r.m.s value Peak value to average value R.M.S. value to average value 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 90 % More than 90% Less than 90% 80 % 90 % More than 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) Rated making capacity of a ciruit breaker is equal to 1.11 X rated symmetrical breaking capacity Rated symmetrical breaking capacity √2 X rated symmetrical breaking capacity 2.55 X rated symmetrical breaking capacity 1.11 X rated symmetrical breaking capacity Rated symmetrical breaking capacity √2 X rated symmetrical breaking capacity 2.55 X rated symmetrical breaking capacity ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The bus bar zone faults are generally Phase to phase faults Double line to ground faults Single line to ground faults Three phase short ciruits Phase to phase faults Double line to ground faults Single line to ground faults Three phase short ciruits ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) A 3 phase, 6 pole induction motor operates on 440 V, 50 Hz, supply. If the actual speed of the motor is 960 rpm the slip will be 0.4 % 4 % 6 % 5 % 0.4 % 4 % 6 % 5 % ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Ns = 120f/PSlip=(Ns-Nr)/NsNs = 1000 and Nr = 960 from equation of slip, S = (1000-960)/1000S = 0.04 or 4%
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 can be started with the help of rotor resistances It's power factor is higher It is suitable for higher speeds It has a higher efficiency It can be started with the help of rotor resistances It's power factor is higher 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.
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