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Shunt Reactors

 

Shunt Reactors
For star-connected shunt reactors each of inductance Lstar on a three phase system of line voltage Vline and frequency f, the lagging reactive power demand QLstar and the lagging reactive line current Iline are:
QLstar = Vline2 / XLstar = Vline2 / 2
pfLstar
Iline = QLstar /
Ö3Vline = Vline / Ö3XLstar
Lstar = Vline2 / 2
p
fQLstar

For delta-connected shunt reactors each of inductance Ldelta on a three phase system of line voltage Vline and frequency f, the lagging reactive power demand QLdelta and the lagging reactive line current Iline are:
QLdelta = 3Vline2 / XLdelta = 3Vline2 / 2
pfLdelta
Iline
= QLdelta / Ö3Vline = Ö3Vline / XLdelta
Ldelta = 3Vline2 / 2
pfQLdelta

Note that for the same lagging reactive power QL:
XLdelta = 3XLstar
Ldelta = 3Lstar

Series Reactors
For series line reactors each of inductance Lseries carrying line current Iline on a three phase system of frequency f, the voltage drop Vdrop across each line reactor and the total lagging reactive power demand QLseries of the set of three line reactors are:
Vdrop = IlineXLseries = 2
pfLseriesIline
QLseries
= 3Vdrop2 / XLseries = 3VdropIline = 3Iline2XLseries = 6pfLseriesIline2
Lseries = QLseries / 6
pfIline2

Note that the apparent power rating Srating of the set of three series line reactors is based on the line voltage Vline and not the voltage drop Vdrop:
Srating =
Ö3VlineIline