Shunt Capacitance VARs

Jan 30, 2009 1 Replies

Hi,



I am trying to figure out how to calculate the shunt capacitance VAR for a project I am looking over.



The data I have is: Voltage=345kV Conductor Size=2-795kcmil Length=12 miles Resistance=0.71428 ohms (total) Reactance=7.11065 ohms (total) Susceptance=86.187 micro-siemen Current=339.167 amps Power Factor=0.967 VARs=51.429 MVAR Power=196.038 MW



The shunt capacitance vars they are showing are 10,258.41 KVARs.



Thanks for your hep.


--Troy


That is correct. The total 3 phase shunt vars is given by 3(Vlg^2)*Ylg Voltage l-g=345/root(3)=199.2 KV Ylg=86.2 micro-seimens Shunt vars (3 phase) =3*(199200^2)*86.2*10^-6 =10.26*10^6 VAR =10.26 MVAR =10,260 KVAR or reduce it to (345^2)*86.187 *10^-6 =10.26 MVAR

Numbers rounded to reasonable (but still overly optimistic) precision. No-one knows the resistance, inductance and capacitance to 5 sig figs-too many Bougerre Factors exist .

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