Question

The reactance that plays a role under steady-state operation of a synchronous machine is called _____.

Short answer

Therefore, the reactance that plays a role under steady-state operation of a synchronous machine is called direct axis synchronous reactance.

Step-by-step solution

write the formula of fault current.

Write the formula of instantaneous ac fault current.

Here, E_g is line-to-neutral prefault behind terminal voltage, X^"_d is a sub transient reactance, X^'_d is a transient reactance, X_d is a synchronous reactance,$\alpha$ is phase between i (t) and e (t) , T^"_d and T^'_d is a time constant.

In equation (1), T^"_d is direct axis short circuit sub transient time constant and T^'_d is direct axis short circuit transient time constant.

Determine the answer.

Write the formula of transient, sub transient and steady state current.

Consider second equation.

I^" =$\frac{E_g}{{X_d}^{"}}$

Consider current at infinity.

Here, I ($\infty$) is the final current, called as steady state current.

Therefore, the reactance that plays a role under steady-state operation of a synchronous machine is called direct axis synchronous reactance.