DGVCL Exam Paper (11-12-2011) In the protection of transformers, harmonic restraint is used to guard against Switching over voltages Lightning Unbalanced protection Magnetizing inrush current Switching over voltages Lightning 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) Buchholz relay causes Tripping for minor faults and alarm for major faults Alarm for both major and minor faults Tripping for both major and minor faults Tripping for major faults and alarm for minor faults Tripping for minor faults and alarm for major faults Alarm for both major and minor faults Tripping for both major and minor faults Tripping for major faults and alarm for minor faults ANSWER DOWNLOAD EXAMIANS APP
DGVCL Exam Paper (11-12-2011) The advantage of slipring induction motor over the squirrel cage induction motor is 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 It is suitable for higher speeds It has a higher efficiency 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.
DGVCL Exam Paper (11-12-2011) The insulation coordination for UHV lines (above 500 kV) is done based on Switching surges Lightning surges Voltage level of the line Lightning and switching surges Switching surges Lightning surges Voltage level of the line Lightning and switching surges ANSWER DOWNLOAD EXAMIANS APP
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) 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 10 MVA 60 MVA 50 MVA 20 MVA 10 MVA 60 MVA 50 MVA 20 MVA ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Short circuit kVA = Base kVA/%X
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