The sustained short circuit current of a generator-with field adjusted for max. rated kva is 2200A.?

Question

Excitation requirement (maximum) is 125KW, 210V. Can the short circuit ratio of this generator be calculated with the available information? If yes, what is the value?

Answer 1

Assumptions: 125 kW = 125 kVA; 3-phase generator.

125 kVA ÷ .210 kV ÷ 1.73 = 344 amps

2200 amps ÷ 344 amps = 6.4:1


The short-circuit ratio of a generator is the ratio of the field current required to produce rated open circuit voltage, to the field current required to produce rated stator current when the generator output terminals are short-circuited. The short-circuit ratio is also the reciprocal of the per unit value of the saturated synchronous reactance. The short-circuit ratio of a generator is a measure of the transient stability of the unit, with higher ratios providing greater stability.