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Variable Frequency Drive VFD Pipeline Applications

Variable Frequency Drives or VFD s have become commonplace on pipeline pumping applications. Variable Frequency Drives VFD s are so often applied to pipeline pumping applications, that the application engineering required has become easier, if not almost routine. pipelineVFD s are installed on pipelines primarily for two reasons; better control of flow/pressure, and energy savings. Additional reasons for pipeline VFD s are reducing inrush currents and the elimination of mechanical stresses often associated with across-the-line starts of large motors.

In years past, engineers often worried about vibration and other torsional issues with applying VFDs to large pipeline motors, but with improvements in VFD design that’s largely a past issue.Toshiba

It is therefore suggested to consider shaft trains supplied with
state-of-the-art VFD technology as torsionally safe and to omit
torsional rotordynamic analysis on such shaft trains”

(From Analysis Guide for Variable Frequency Drive Operated Centrifugal Pumps. Kaiser, Osman, Dickau 2008)

Control of pipeline flow or pressure with a VFD is well-established science. The majority of pipeline VFD s are controlled externally, and simply follow startstop logic and speed. It is very possible, given today’s technology, to simply feed a pressure signal, or other control variables, directly into the VFD and have it operate as a stand-alone controller. This is rare in most pipeline operations, but not unheard of.

The energy savings possible by controlling a large HP medium voltage motor with a medium voltage drive is often very attractive to pipeline operators, in lieu of using valves or other mechanical means.

With increased pressure on the power grid, utilities may demand that a pipeline operator ceases from starting a large horsepower medium voltage motor across the line. The line starts also create mechanical stresses on the couplings, rotor, shaft, and pump. VFDs are inherently softstarting.

It is possible, in some cases, to use reduced voltage “soft starters” as well, but careful consideration of the actual load characteristics must be taken. (See When Should you Use a VFD as a Softstarter?)

There are numerous cases, where a medium voltage VFD is used in a pipeline to run the pump motor at a fixed speed, which is often not 60 hz. This speed may be varied over time as system demand changes, but in general, is operated at one speed. However, even so, the pipeline operator gets the benefits of softstarting, energy savings, and an exact speed match.

Most pipeline VFD applications are centrifugal pumps, but not always. VFDs area also applied on positive displacement pumps and compressors for exacting process control as well.

The majority of pipeline VFDs are large horsepower, and therefore, almost always medium voltage drives.

EMA has a long history of applying medium voltage VFDs to pipelines and other applications. Call us at 770-448-4644 OR hit any of the contact methods on the right of this page. We have medium voltage VFDs in stock for sale or rental.

No One, Anywhere, is Better at Drives than we are.


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