... current increases with the voltage drop. Obviously, A, B, C three inflection points are the most energy-efficient point. ... rated power is PW, rated outlet pressure is P, and the rated flow is Q.Then produce the ... rated flow, shaft power: PW = K * P * Q Where K is a constant, through the valve ... 2, in this case, the shaft power is: PW1 = P * Q / 2 = 0.5PW Adopted frequency control, the ...