Brochure
110110
6.4.1 Measuring system
The force measurement is made by absorbing the forces on the rotating system
(impeller and shaft) through a measuring system.
The axial force can e.g. be measured by moving the axial bearing outside the mo-
tor and mount it on a dynamometer, see figure 6.15. The axial forces occuring
during operation are absorbed in the bearing and can thereby be measured with a
dynamometer.
Axial and radial forces can also be measured by mounting the shaft in a magnetic
bearing where it is fixed with magnetic forces. The shaft is fixed magnetical both in
the axial and radial direction. The mounting force is measured, and the magnetic
bearing provides information about both radial and axial forces, see figure 6.16.
Radial and axial force measurements with magnetic bearing are very fast, and
both the static and the dynamic forces can therefore be measured.
By measurement in the magnetic bearing, the pump hydraulic is mounted directly
on the magnetic bearing. It is important that the fixing flange geometry is a pre-
cise reflection in the pump geometry because small changes in the flow condi-
tions in the cavities can cause considerable dierences in the forces aecting on
the impeller.
Figure 6.15: Axial force measurement
through dynamometer on the bearing.
Figure 6.16: Radial and axial force meas-
urement with magnetic bearing.
6. Pump tests
Support
bearing
Axial sensor
Radial magnetic bearing
Radial sensor
Axial magnetic bearing
Radial sensor
Radial sensor
Radial magnetic bearing
Axial sensor
Support bearing
Dynamometer
Axial bearing