This is one of the best applications for an AC drive. In most fan/pump applications, there is a need to vary the output of the fan/pump. This is very easy to achieve with an AC drive. Plus you get the benefit of reduced energy cost of running the motor!!!
Suitability of VFD for pumps.
VFD’s are well suited to pumping applications. Many are manufactured to include motor speed/torque profiles specifically intended to optimize pump performance. However, there are some issues which must be considered before deciding on the use of VFD’s:
- Suitability of the motors – the motors must be rated for inverter-duty to withstand the higher electrical stresses drives can impose. Some older motors were not built to withstand these stresses and may fail prematurely.
- Distance of motors from VFD’s – the VFD’s will induce voltage transients on the load connectors. If these connectors are too long (manufacturers often suggest keeping motor lead length to 50m or less), the voltage at the motor terminals may increase to several factors above nominal, which can also cause premature motor failure.
- VFD installation location and environmental conditions – this will determine the type of enclosure and conditions under which the VFD’s will operate. VFD’s which must withstand severe moisture, temperature swings, or dust can fail prematurely and must be protected by suitably rated enclosures.