Controller combination in which the setpoint Q for the flow rate controller and the setpoint p for the pressure controller are pre-defined electrically on proportional valves. In this way the performance map of a flow rate control system can be superimposed on a performance map of a pressure control system and in this way the losses with closed loads significantly reduced by operating the flow rate at a low pressure, the so-called standby pressure (approx. 15...20 bar) (Figure D 74).
Figure D 74: Pressure-flow (p-Q-) control; a) Characteristic curve, b) Pump operation