Grundfos A/s

Bent Larden

Niels D Jensen

Kurt F Nielsen

In the case of a pumping set comprising an electric motor and a rotary pump driven by the same, the r.p.m. may be controlled as a function of selected operating parameters of the set in steps within the area of a characteristic field, the limits of which are determined on the one hand by the two modulating graphs for the maximum and minimum r.p.m. figures and on the other hand by the co-ordinates delivery head and delivery flow. A particular partial span may in each case be determined on the modulating graphs valid for constant r.p.m. figures. An r.p.m. switching action is triggered upon reaching the operating parameters of the set representative for the terminal values of the partial spans, the r.p.m. being lowered if the one terminal value is reached on one partial span with the greater delivery head and the lesser delivery flow, and raised if the other terminal value on the partial span in question is obtained with the lesser delivery head and the greater delivery flow.

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Rodkaersbro, Denmark

Bent Larden