VFD nominal rpm parameter
VFD nominal rpm parameter
(OP)
What are the effects of running a pump that has a namplate rating of 3500 rpm being run on a drive than has the nominal rpm parameter set to 1750 rpm ?
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VFD nominal rpm parameter
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RE: VFD nominal rpm parameter
Reduced efficiency.
Much lower head pressure.
Keith Cress
kcress - http://www.flaminsystems.com
RE: VFD nominal rpm parameter
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RE: VFD nominal rpm parameter
Above the base speed, the drive can not keep U/f constant, so you get field weakening. Field weakening means that available torque goes down with speed squared and that "thermal torque" falls approximately as 1/f so that output power is constant up to a point where the maximum torque is reached and the drive stalls.
Gunnar Englund
www.gke.org
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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: VFD nominal rpm parameter
Do you mean you are running at half speed or do you mean the VFD's parameter for showing rpm has not been set to a 2-pole motor?
If the latter: most VFD's will use Hz internally as the reference to set the V/F base frequency and use rpm to use as a display reference. So the need to set the parameter of rpm to the correct motor base rpm is typically used to ensure the display is correct to the speed. I.e. you are using a 2 pole motor instead of the more typical 4 pole motor.
RE: VFD nominal rpm parameter
VFD rpm parameter was set at 1750rpm.
RE: VFD nominal rpm parameter
Gunnar Englund
www.gke.org
--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...
RE: VFD nominal rpm parameter
Now, the rpm setpoint could be either just for display or it could be used to set the nominal frequency. But, it's not likely to be used to set the base frequency because then you'd also have to enter the slip and the motor poles to get the right base frequency calculated. So, to get the right base frequency would require correctly setting 3 parameters which is a poor method for obtaining such an important motor parameter. But then, using 1800rpm/4-pole would give the same base frequency and V/Hz ratio as using 3600rpm/2-pole.