VFD Pump Control
VFD Pump Control
(OP)
I am using a VFD to control a constant pressure water pump.In the technical specifications of the pump,it says 90% load at 50 hz.
1.Is it possible for me to load the pump above 90% by using VFD?(by increasing/decreasing frequency?)
2.If I were to operate the pump at 45 hz,what would the motor current be?Please provide me formula for relation between current and frequency...
Thanks & Regards,
Alan
1.Is it possible for me to load the pump above 90% by using VFD?(by increasing/decreasing frequency?)
2.If I were to operate the pump at 45 hz,what would the motor current be?Please provide me formula for relation between current and frequency...
Thanks & Regards,
Alan





RE: VFD Pump Control
The relation between the current and frequency may be fixed for a linear load, but for a pump the pump laws predominate, possibly modified by the system dynamic characteristics.
Post a question in a pumping forum asking the effect of changing speed on pump capacity, and motor loading.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: VFD Pump Control
"Will work for salami"
RE: VFD Pump Control
For the sake of possibility, yes its possible. But why would you manually change it? If it is a constant pressure, the VFD should automatically adjust according to your system requirements.
Forget about the formula since it will not going to be that simple. If you already had the VFD, measure it.
RE: VFD Pump Control
Im sorry the pump is not constant pressure.The application is for a chilled water pump and that means variable flow/variable pressure.The HVAC enginner asked me whether it is possible to load the pump above 90% and we finalising the pump and vfd ,so just wanted to confirm.
Yes,the pump is centrifugal.