Frequency Controllers for Centrifugal Pumps

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I am looking for information regarding frequency controllers (or Variable Frequency Drives) used for pumps:

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8 Answers

  2. SIDE Industrie is a company facturing Direct In-line Pumping System (DIP Systeme) for 15 years and using VFD since the begining .

    The advantage is of course energy saving but as well we developped a integrated SCADA called OmniDIP that analyse and optimize the pumping system continuously .

    do not hesitate to go on our website or contact us :

    http://www.side-industrie.com/index.php/en/alc-deck

    info about our OmniDIP :

    OmniDIP® is a Self-monitoring system dedicated to the DIP Systeme®.

    It checks automatically and continuously all the processes through 230 parameters per pump in order to guarantee the optimal operation as long as possible and in order to avoid any useless intervention of a technician. It analyzes so precisely that it allows to forecast and optimize and not only to inform when there is a technical fault nor to only log data.The factory service is as well checking or updating the system via OmniDIP® and will handle as well automatically preventive alerts sent by the DIP Systeme®.

    Some automatic process checks of the DIP Systeme®, such as automatic clearing, automatic cleaning or respect of the level setpoint for example, can be done from the OmniDIP® , so that we can know the state of the sensor, the state of the motor or we can test the automatic alternance for example thanks to the magnified exam that analyses every second under the factory control.

    If anything particular is detected a summary report is sent to the known user and in the event a physical intervention is required, our technician will contact and guide the user. The Customer Access allows the display of the functioning of DIP Systeme®, and to edit summary reports over a choosen period of time.

    You can then directly check on the average consumption, the pumped volumes, the run time and the optimisation actions made by the Selfmonitoring OmniDIP® .

    Thanks to the remote control system OmniDIP®, the DIP Systeme® solution brings intervention comfort, safety and long terms savings , energy included !

     

  3. VFDs work by rectifying power to DC and then inverting to a frequency set by the controller. This will run the pump at the speed dependent on that frequency and the number of poles. There are a lot of advantages to this the principal being energy saving as the power is drawn for the operation required rather than controlling by losing head over control valves. It allows for a more general pump selection and to cover a sometimes wider range of flows and heads. It is possible to supersynchronise that is the drive to a higher speed than the grid power supply. Pumps are generally built for operation of 60 Hz power and so this should not be a problem.

    Points to watch are that at low speeds the motor may need additional cooling  as the fan is turning slower. This is generally achieved by selecting a higher motor frame size.

    Also some pumps especially borehole pumps have a relatively high minimum speed to ensure that bearings operate correctly.

    Finally the use of inverters can cause harmonics interference at the mains point of coupling. This can be controlled by the use of more sophisticated inverters. more pulses, or through harmonics filters. Generally a before and after installation survey is needed for major installations.

  4. VFDs in pumping applications provide energy savings and can provide a  great deal of mechanical information in addition to controlling the flow more effectively. Energy savings in the 40% range are not uncommon. They provide highly efficient power factor control of the motor, reducing heat and improving the life of the motor.

    www.drive-chat.com

     

  5. The Frequency converter is typically an alternative to traditional valves for the regulation of the flow rate. The correct query is about the convenience of using either FC or FCV.

    The reduction of flow rate by FCV means the waste of the energy caused by the valves, and therefore FC is typically considered convenient. However FC dissipates some energy continuously (between 3% and 5%) and therefore it may not be convenient in those cases when the pump is designed to work stably at the maximum flow rate (FCV fully open)

    The cost of FC is very much affected by the flow rate of the pump, in the way that FC is less expensive for small diameters but much more costly than FCV in the case of high motor rated power.

    Hence the evaluation of the conveniency has to be according to the planned way of use and pump capacity.

  6. Your best option is to visit VFD manufacturer websites. Most have application notes on their products.

  7. I like the explanation of Thibaud.
    In simple terms, motors are built for a standard frequency, say in America 60 Hz, in Europe 50.
    If you plug an american motor in Europe (at correct design voltage) it will turn slower (at approx 50/60 rpm because of the frecuency change).
    A variable Frequency drive control intentionally changes the frequency of the feed alternating current, thus becomes a speed control.
    Hope it helps the understanding

     

  8. 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