GETCO Exam Paper (22-07-2015) The RMS value of the voltage u(t) = 3 + 4 cos(3t) is 7 4.12 5 3 + 2(1.41) 7 4.12 5 3 + 2(1.41) ANSWER EXPLANATION DOWNLOAD EXAMIANS APP if voltage is given by,v(t) = V₀ + V₁ cos(3t) + V₂ cos(5t)+ …RMS value is given by,√( V₀² + (V₁/√2)² + (V₂/√2)² + …)
GETCO Exam Paper (22-07-2015) A transformer has negative voltage regulation when its load PF is leading lagging zero unity leading lagging zero unity ANSWER EXPLANATION DOWNLOAD EXAMIANS APP Voltage regulation = ((no load voltage)-(full load voltage)/(no load voltage))VR at leading PF = ((I*R*cosφ)-(I*X*sinφ))/VVR at lagging PF = ((I*R*cosφ)+(I*X*sinφ))/V
GETCO Exam Paper (22-07-2015) In rotating electrical machines, the insulation temperature limit for class B type is 105˚C 150˚C 180˚C 130˚C 105˚C 150˚C 180˚C 130˚C ANSWER EXPLANATION DOWNLOAD EXAMIANS APP insulation Class and temperature limit(in ˚C) is given below:Y - 90A- 105E- 120B-130F-155H-180C- above 180
GETCO Exam Paper (22-07-2015) For eliminating 7th harmonics from generated EMF in alternator the fractional pitch must be 6\7 7\8 5\6 2\3 6\7 7\8 5\6 2\3 ANSWER EXPLANATION DOWNLOAD EXAMIANS APP fractional pitch = Cos( α/2)α is obtain from: (nα/2)=90˚ where n is harmonicα=25.7143˚fractional pitch=6/7
GETCO Exam Paper (22-07-2015) Which of the following is not function of substation batteries? provide supply to the excitation system emergency lighting circuits operating automatic control circuits operating protective relay systems provide supply to the excitation system emergency lighting circuits operating automatic control circuits operating protective relay systems ANSWER DOWNLOAD EXAMIANS APP
GETCO Exam Paper (22-07-2015) Fast excitation system of the generator will _____ Improve the dynamic stability Improve the reactive power control Improve the power factor Improve the voltage control Improve the dynamic stability Improve the reactive power control Improve the power factor Improve the voltage control ANSWER DOWNLOAD EXAMIANS APP
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