MGVCL Exam Paper (30-07-2021 Shift 3)
The current flowing in to a balanced delta connected load through line 'a' is 10 A when the conductor of line ’b’ is open. With the current in line 'a' as reference, compute the symmetrical components of the line currents. Assume the phase sequence of ’abc’.
The ratio of full load current to short circuit current = 1/6 Xsc = j/(1/6) External reactance required = j*((1/6) - 0.06)) = j*0.106 pu Full load current = (40*1000)/(√3*15) = 1539.6 A Per unit reactance = j*0.106 = (I*Xr)/V j*0.15 = (1539.6*Xb)/((15/√3)*1000)) = 0.60 ohm
Frequency response analysis is the technique whereby a sinusoidal test signal is used to measure points on the frequency response of a transfer function or impedance function. Sweep Frequency Response Analysis (SFRA) testing provides insight into the mechanical and electrical integrity of transformers.
Main Purpose of SFRA Test: Transformer Core displacement Winding displacement for both rotor and transformer Broken or loosen clamp connections Inter turn short circuit Internal short circuit Winding to Core Earth fault Winding Open circuit condition
The capacity factor is the ratio of an actual electrical energy output over a given period of time to the maximum possible electrical energy output over that period. Nuclear power plants are at the high end of the range of capacity factors
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