Home » Wiki » VFD over frequency running

VFD over frequency running

Stepping up motor speed with variable frequency drive (VFD) creates a problem of overheating of windings, overheating of stampings and magnetic saturation of motor stampings. If all these are taken care of, stepping up by a ratio of 2:1 may even be possible. Economics do not favor this arrangement. I do not understand why anyone would want to use variable frequency drive for high ratio seed variation when alternative methods are less expensive and more energy efficient.

There are circumstances when an over frequency VFD makes sense. Specifically, in some cases of centrifugal pumps and compressors, the RPM is determined by flow and pressure. In those cases, you may need, for example, 7000 RPM, and that number isn't negotiable. The alternative is to use a gearbox. Gearboxes are expensive and high maintenance. A well-engineered direct drive is cheaper and lower maintenance. Motors for over frequency VFD may have to be special. The variable frequency drive will be simpler than gear box assembly.

Just to throw something completely different into the mix submersible motors are often run on VFD for many reasons, level control, constant flow, the vfd pumps with internal cooling needed to maintain a minimum speed to allow for cooling and in waste water pumping there was also consideration to be given to clogging of the impellers a general rule was not to run below a certain frequency from memory around 25 or 30 hertz.

Post a Comment:

Plz Calculate (2 * 6) =
(Your comment will show after approved.)

You may also like:

Featured Articles
Variable frequency drive Rectifier Variable frequency drive RectifierTo understand variable frequency drive (VFD) better, it's necessary to explain some of the main parts of the variable frequency ...
VFD controlled Induction motor ... VFD controlled Induction motor Efficiency measurementThis paper presents a procedure to measure the efficiency on an induction motor fed by a VFD by the all operation range to speed ...
VFD: Pulse Width Modulation (PWM) VFD: Pulse Width Modulation (PWM)Pulse Width Modulation (PWM) VFDs provide a more sinusoidal current output to control frequency and voltage supplied to an AC ...
Variable frequency drive Advantages & ... VFDs are good for variable speed, in a water pump this is used to maintain a steady pressure, they will smooth out variances in ...
Variable frequency drive Energy saving Variable frequency drive Energy savingEnergy can be saved in a VFD by reducing the losses in the electric motor or by reducing the energy consumption of the variable ...
Variable Frequency Drive Service
VFD manufacturers
Variable Frequency Drive Sales Email buy@vfds.org
Variable Frequency Drive Support Email tech@vfds.org