The units will have the same design as the 600 volt reactors, thus impedance is proportionately lower. Impedance is down to 4.3% (from 5%) or 2.6% (from 3%). 600/690 = 86.9% multiplied by 5% results in 4.3% (or multiplied by 3% results in 2.6%). Current ratings are standard 600 volt ratings.