MAX POWER @ RATED IMPELLER = Power at end of curve
When pump start with “open valve” (automatic start) or there is a minimum flow line, its electrical motor power shall be selected at end of curve (Maximum power) of rated impeller.
Very important Point: Note that in the all cases Maximum power does not occur in the end of curve. This is related to Ns (Specific Speed) and shape of impeller. In mixed flow and axial flow impeller, max power is to be happened another location of curve. In the mixed flow impeller max power is occurred in the middle of curve and in the axial flow impeller it is happened in the shutoff valve situation.
- For pumps with open valve (automatic start) or minimum flow line, power shall be selected at end of curve.
- MAX POWER @ RATED IMPELLER shall be equal end of curve.
- Margin between driver power and max. power at rated impeller diameter shall be greater than the values given in table 12 of API 610.