Short Circuit Value
Short Circuit Value
(OP)
I have carried out ANSI 30cycle Short Circuit Study in SKM but the Values of ANSI_30cycle_3P & SLG is 20A & 12A respectively at 13.8kV. The utility is rated as 500MVA.
What might be the problem.Why the Value is so small? I cannot do the settings for the relays unless I rectify this.
What might be the problem.Why the Value is so small? I cannot do the settings for the relays unless I rectify this.






RE: Short Circuit Value
Is the Utility 3 phase short-circuit contribtuion of 500 MVA at 13.8kV ? 3P SC = 500 MVA / ( sqrt(3*13800 ) = 20.92kA
RE: Short Circuit Value
Rafiq Bulsara
http://www.srengineersct.com
RE: Short Circuit Value
Now the starting inrush for Chiller#1 is much higher then the minimum fault current (I30cycSLG i.e. 2231.75), so I want to now at how many times of FLA of Chiller, the Instantaneous Protection shall be set at???
RE: Short Circuit Value
What does chiller starting kA has to do with SLG fault current? Motor starting will not be seen by the ground fault element.
As for actual settings, it depends on your objectives. Low as possible but high enough to coordinate and avoid nuisance trips.
Rafiq Bulsara
http://www.srengineersct.com