Inrush Current Exceeding SCA
Inrush Current Exceeding SCA
(OP)
Is this a correct statement?
"In general, if the inrush current exceeds the available SCA, the inrush event would take more time and voltage drop would be larger"
Thanks.
"In general, if the inrush current exceeds the available SCA, the inrush event would take more time and voltage drop would be larger"
Thanks.






RE: Inrush Current Exceeding SCA
RE: Inrush Current Exceeding SCA
But this is assuming here that you are defining "inrush" as motor starting current, not it's true definition as MAGNETIZING current, which applies to any induction device like an AC motor or a transformer. In the true definition of "inrush current" the statement would be true, albeit impossible because, as dpc noted first, the inrush CANNOT be higher than the SC current. The SC current should represent the MAXIMUM current available in the circuit. So a "true-er" way of saying that is that if the rated inrush current of an inductive device is higher than the available SC current, the SC current BECOMES the inrush current value, which may cause a voltage drop on the circuit.
"Will work for (the memory of) salami"
RE: Inrush Current Exceeding SCA
The inrush may exceed the defined symmetrical short circuit current but it may not exceed the asymmetrical peak current.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Inrush Current Exceeding SCA
RE: Inrush Current Exceeding SCA
very elevated and the core will be saturated. The inductance will decrease dramatically and the inrush current will be elevated.
Now, even if we will neglect this inductance, the primary winding impedance will exist since the resistance and the leakage magnetic flow reactance will not be changed.
In this case, the maximum short-circuit current peak value[Ip=1.7-2*sqrt(2)*Ik] upstream the transformer location will be more than transformer inrush current, any way.
Only if we could supply the transformer with the rated voltage-unchanged-then the inrush current would be more.
There are some studies how an inserted resistance could mitigate the inrush current.See [for instance]:
Analytical Study of Transformer Inrush Current Transients and Its Applications
http://www.researchgate.net/publication/242597844_...