MGVCL Exam Paper (30-07-2021 Shift 1)
Murray loop test is performed on a faulty cable 300 m long. At balance, the resistance connected to the faulty core was set at 15 Ω and the resistance of the resistor connected to the sound core was 45 Ω. Calculate the distance of the fault point from the test end.
The V-curves of a synchronous motor show relationship between Armature current (Ia) and Excitation current (If). The Inverted V-curves of a synchronous motor show relationship between power factor (pf) and field excitation (If).
The ratio of full load current to short circuit current = 1/5 Xsc = j/(1/5) External reactance required = j*((1/5) - 0.05)) = j*0.15 pu Full load current = (30*1000)/(√3*11) = 1574.6 A Per unit reactance = j*0.15 = (I*Xr)/V j*0.15 = (1574.6*Xb)/((11/√3)*1000)) = 0.60 ohm
EXAMIANS