Gents
if the proposed transmission line is at high altitude area (more than 2000m above sea level) with a span of 300km, 345kV..by simple high level analysis, what are the considerations to be made in design to minimise the line cost in terms of insulation voltage levels?
thanks,
Danilo
Gents,thanks for the replies.
The assumed MVA Base is 100 MVA.
Assuming the location of the fault at Cable D is at utility end and if the cable impedances of A,B & C are significant, does it make sense to include the cable impedances contribution into fault current?
Davidbeach mentioned that...
I agree
With the generator off;
A fault adjacent to the utility bus will be limited by the utility immpedance.
A fault on the generator bus will limited by the utility impedance and by the impedance of 4 cables in parallel.
But when the generator is on, referring on the above diagram, I...
Thanks. i am trying to figure out if current divider principle can be applied to short circuit analysis. by just looking at the diagram ,the fault contribution from the generator appears to be divided among the 4 cables which includes the faulted cable D.Otherwise, the fault contribution from...
Thanks
when CB is on and assuming the ff:
cable impedances = 1 p.u/cable
utility impedance = 0.5 p.u
generator impdance = 1.5 p.u
the fault current is 0.393 p.u. could you suggest how do you derive the generator contribution on the fault current? does part of the fault current
from generator...
Gents,
please see attached SLD..all loads are neglected. If CB is off and on, what is the equivalent circuit diagram? Cable is 5km long each.
thanks,
Danilo
Thanks again for the replies.
Just to clarify that fault occured at one of the 33kV cable feeders terminated at 33kV bus (Utility) and the other end to 33kV generator bus where the CB is OFF.
Immediately after the fault, can I neglect the impedance of the faulted cable?
regards,
Danilo
Gents
thanks for your replies.
I am thinking of neglecting the impedance of the cables during the fault condition at one of the cables when the generator CB is OFF and consider the cable impedance only when the generator is ON. I just dont know if my assumption is correct. what do you think...
Gents,
Just want to get your opinion regarding the fault calculation on 33kV feeder line
if the load are neglected and do not contribute into the fault and are fed by 4 x 33kV feeder cables 5km long and terminated to 33kV generator terminal bus at one end , should the impedance of cable...
Thanks Krisys..i will use it for the setting of distance relay..I agree with all of you to include the value of resistive component. I have a follow up question regarding angle displacement:
Is it possible to have at the 132kv source an available MVA (positive phase sequence) with an angle...
Gents,
Could you advise please if its normal to assume that parameters of positive phase sequence is equal to negative phase sequence at single line to ground fault? Is it possible to derive from positive and zero phase sequences reactive MVA ratings the source available MVA ? Grateful if...
Thanks..im thinking maybe by ignoring the R, the calculation is a bit conservative since the short circuit capacity of the line will increase. I just dont from the point of view of protection system if being conservative makes the system more reliable and secured..what do you think?
Thanks Gents for your replies.
its 132kv line and the impedance is .9+j1.1 ohms..sorry for the error.. im doing a per unit method at the moment to initially compute the fault currents.
is it recommended to ignore the R component of the line?
regards,
Danilo
Gents,
I have a line impedance of 0.9+j0.1(positive phase sequence) on a 15km transmission line, can i ignore the 0.9 resistance in the calculation of fault current using per unit method? or is this still relevant given that length of transmission line?
many thanks,
Danilo
