Thibaud, Below is a brief ...

Thibaud,

Below is a brief explanation of how a typical VFD works. For pumps, if you're familiar with a pump curve, the VFD essentially allows you to establish a new curve based on the new RPM you run the motor at when changing the frequency on your VFD drive. So, let's say that your pump is designed to run a 3450 RPM at 60 Hz. At this RPM the pump has a specific curve for flow and pressure based on the impeller design, etc. When you put a VFD on the pump you can now adjust the Hz to say 45 which will lower the RPM of the motor and essentially lower the same curve line on your pump curve chart. The pump acts in the same way just at a lower flow and pressure.

VFD's can be energy savers and allow you to vary the flow and pressure to match your specific design and run efficiently there. One thing to keep in mind when using VFD's with drive motors, especially for pumps, is that you need to make sure your motor is "inverter" rated or in other words can be used with a VFD. Most motors cannot handle a low turn down in frequency and speed without generating a lot of heat and burning out. Check with your motor manufacturer on how it will work with a VFD.

I hope this helps you a little. There is a lot of good info on the web so do your research and then talk to a VFD drive manufacturer such as Danfoss, Allen Bradley Powerflex, Siemens, etc.

Regards,

Steven Johnson