Tuesday, May 2, 2017
Assumption: Generator Xd''=0.20, Xs=1.5 pu.
Now, Generally Speaking if we speak of bus fault at generator terminals we say fault current =1 (pu voltage)/0.20= 5 pu. Similarly fault current after 5 seconds or so =1/(1.5)=0.66 pu.
1) The concern is that 1 pu voltage assumed is generator open circuit terminal voltage. So internal voltage generated by machine is 1+(armature current(phasor)*reactance(phasor)). This value reaches up to 1.5-2 times the terminal voltage. All the reac ...