This study points on the operation of a pumping station test rig equipped with 3 vertical centrifugal pumps, with variable speed, coupled in parallel. We investigated the pumps operation by imposing reference levels for the pumping head, then attaining the requested duty points through rotational speed control. On this test rig, the pumped flow rate is controlled by a built-in software, where the pumping scheduling algorithm relies on a sensor-less control method, based on the pump performance curve and affinity laws. The setup allows the measurement of the pumps head (displayed on rig's control panel) and rotational speed of each motor. According to the pumping schedule, when a number of n pumps are operating (where n = 2 or n = 3), then (n – 1) pumps run at nominal speed, while the remaining pump runs at a speed lower than, or equal to the nominal speed. We built in EPANET the numerical model of this test rig and calibrate the model upon experimental data, using simple control statements for the discharge valve and speed patterns for pumps. Due to the calibration, a perfect match resulted between experimental readings and numerical duty points. Further, we built an alternative numerical model, which allowed analysing additional duty points, then we plot them on a chart, together with the experimental duty points: all points fit into the operation areas attached to the pumping schedule. The proposed approach proved to be useful to study further the pumps operation, with a minimal experimental effort.