Data and working hypotheses
Application of variable speed to centrifugal pumping

The pump selected is a type NM 252 from Ingersoll Dresser Pumps with the following characteristics:

• maximum output flow: Q_RM = 1,100m³/h ;

• height of elevation: H_RM = 59 m ;

• maximum efficiency: η_M = 85% ;

• power consumption at maximum output: P_RM = 208.5 kW.

The H(Q), P (Q), η(Q) curves for the NM 252 pump are shown on the graph in figure 1.

In our application, we adopt the point defined as follows as the nominal point of the pump:

• rated flow: Q_N = 1 300 m³/h ;

• height of elevation: H_N = 50 m ;

• power consumption: P_N = 218 kW.