DGVCL Exam Paper (11-12-2011) An IDMT relay provides An inverse time current characteristic An inverse characteristic for low values of the fault current and a definite time characteristic for high values of the fault current A definite time characteristic for low values of the failt current and an inverse characteristic for high values of the fault current A definite time cuttent characteristic An inverse time current characteristic An inverse characteristic for low values of the fault current and a definite time characteristic for high values of the fault current A definite time characteristic for low values of the failt current and an inverse characteristic for high values of the fault current A definite time cuttent characteristic ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) Which of the following correctly represents the sequence of operations of isolator, circiut breaker and earthing switch while opening a circuit? Close earthing switch - open ciruit- breaker-open islotor Close circuit breaker-close isolator - open earthing switch Open isolator close circuit breaker-open earthing switch Open circuit breaker-open isolator-close earthing switch Close earthing switch - open ciruit- breaker-open islotor Close circuit breaker-close isolator - open earthing switch Open isolator close circuit breaker-open earthing switch Open circuit breaker-open isolator-close earthing switch 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 4 % 0.4 % 6 % 5 % 4 % 0.4 % 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) In carrier current protection, the purpose of the wave trap is for Trapping high frequency waves entering into generator/transformer unit. Trapping power frequency waves All of these Tripping fault current Trapping high frequency waves entering into generator/transformer unit. Trapping power frequency waves All of these Tripping fault current ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Lightning Switching over voltages Unbalanced protection Magnetizing inrush current Lightning Switching over voltages Unbalanced protection Magnetizing inrush current 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) An AC series circuit has R = 6 Ω, XL = 20 Ω and Xc = 12 Ω. The ciruit power factor will be 0.6 lagging 0.6 leading 0.8 lagging 0.5 leading 0.6 lagging 0.6 leading 0.8 lagging 0.5 leading ANSWER DOWNLOAD EXAMIANS APP
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