Why is the X/ R ratio taken as 14? (In short Circuit Analysis)
There is no standard for X/R ratio.
But time constant t = L/R
In power system we have taken t = (X/R) /(2πf)
As per IEC 62271; time constant value is 45 ms.
t = 45 ms.
t = (X/R) /(2πf)
0.045 = (X/R)/ (2 x 3.142 x 50)
X/R = 0.045 * (2 x 3.142 x 50)
X/R = 14.137 (approximately equal to 14)
- X/R = 14 for 50 Hz system
- X/R = 17 for 60 Hz system.