Abstract：

Makes an analysis and points out that the engineering conditions of variable speed working condition of water pump in line with the proportionality law are as follows: non-back-pressure system，all parallel pumps changing speed synchronously (including a single variable speed pump system) and fixed pipeline characteristic curve. Energy saving effect analysis of variable speed pumps should be based on the energy consumption comparison of the pump variable speed control to other flow control methods in conditions of achieving the same flow, but not to the design working condition.