A 50 MVA, 10 kV, 50 Hz , star-connected, unloaded three-phase alternator has a synchronous reactance of 1 p.u. and a sub-transient reactance of 0.2 p. - General NAT GATE EE 2016 Question Paper (07-Feb-2016) (Shift 2) | ExamTest.live

mediumNATGATE EE 2016 Question Paper (07-Feb-2016) (Shift 2)General

1 mark

A 50 M V A, 10 kV, 50 Hz, star-connected, unloaded three-phase alternator has a synchronous reactance of 1 p.u. and a sub-transient reactance of 0.2 p . u . If a 3-phase short circuit occurs close to the generator terminals, the ratio of initial and final values of the sinusoidal component of the short circuit current is ________.

Correct Answer

4.9-5.1

Solution & Step-by-step Explanation

Fault current is inversely proportional to reactance during fault. \Rightarrow I_{f} \propto \frac{1}{X} \Rightarrow \frac{in t ia l c u rre n t}{f ina l c u rre n t} = \frac{S y n c h ro n o u s re a c t an ce}{S u b - t r an s i e n t re a c t an ce} = \frac{1}{0.2} = 5

Try it yourself before checking the explanation above.

A 50 M V A, 10 kV, 50 Hz, star-connected, unloaded three-phase alternator has a synchronous reactance of 1 p.u. and a sub-transient reactance of 0.2 p . u . If a 3-phase short circuit occurs close to the generator terminals, the ratio of initial and final values of the sinusoidal component of the short circuit current is ________.