The figure below shows the per-phase Open Circuit Characteristics (measured in V) and Short Circuit Characteristics (measured in A) of a 14 kVA, 400 V, 50 Hz, 4-pole, 3-phase, delta connected alternator, driven at 1500 rpm. The field current, is measured in A. Readings taken are marked as respective coordinates in the figure. Ratio of the unsaturated and saturated synchronous impedances () of the alternator is closest to:
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A graph with horizontal axis I_f (field current, A) and two vertical axes: V_oc (left, open-circuit voltage, V) and I_sc (right, short-circuit current, A). Two curves originate from the origin region: (1) OCC — open circuit characteristic, plotted through points (0,10), (1,110), (2,210), rising linearly at first (air-gap line, slope 100 V/A, intercept 10 V — matching residual magnetism) then bending over (saturating) to reach (8,400) at the top right, labelled 'OCC'. (2) SCC — short circuit characteristic, a straight line from (0,0) through (4,20), labelled 'SCC', with much smaller slope (5 A/A), lying below and to the right, not saturating.
- (A)
2.100
- (B)
2.025
- (C)
2.000
- (D)
1.000