Pump Stations: CSV vs VFD
None of the problems associated with VFD exist when using a Cycle Stop Valve for control. With a CSV, the motor is always spinning at full RPM,
but the amps are reduced similarly to varying the speed. When the motor is spinning at full speed, the cooling fan always provides adequate cooling.
Spinning at full speed also means there are no problems with resonance frequency vibrations. Running on pure sinusoidal power, instead of the
unstable waveform produced by a VFD, means there are no problems with harmonics, voltage spikes, or bearing currents.
A manufacturer of VFD pump stations said in a recent article:
?It is not advisable to get caught up in an overly elaborate system just because the
technology?s available. With the advancements in the electronic industry, it?s tempting to add complexity to the electronics of a
pump station. It is recommended that people keep things as simple as possible. When you add complexity, it doesn?t always make the
application better suited for the job. With more complex electronics, the maintenance and repairs can become more complex and
difficult, and often there is not much value added. It is important that irrigation professionals understand what the electronics can
and can?t do. No one wants to get dazzled by bright lights, only to find out that their product is not easy to maintain.?
Nothing is as simple as a CSV, and that is part of what makes it so advanced. The CSV has no wires or electric components. The system
pressure directly powers the CSV. This means the CSV can react instantly to any change in pressure, which is much faster than a VFD can change
the RPM of a motor.
While other manufacturers keep adding electronics and making systems more complicated, the simplicity of the Cycle Stop Valve sets it apart from
the others. The picture below shows a recent pump station. Using Cycle Stop Valves to enhance the natural flow and horsepower characteristics
of pumps eliminates the need for VFD?s and their associated side effects.
Valves have gotten a bad rap from people who honestly myth-understand. However, the expensive and short-lived nature of VFD systems, are
extremely profitable for the manufacturer at the expense of the end user. Therefore, finding a reputable pump station manufacturer, means
finding one who admits that a VFD does not save energy, and Valve control is not like ?driving a car with one foot on the gas and the other
on the brake?.