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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
When it comes to powering pumps, energy efficiency is critical. In the water sector, the link between energy usage and pumping is well known. Of course, motor efficiencies and pump efficiencies are key components of overall energy efficiency. But the type (single-phase or three-phase) and quality of the power also affect energy consumption and lifecycle costs related to equipment life and maintenance. Variable frequency drives can be used to convert single-phase to threephase power, improving efficiency and enhancing operations.
Author(s)
Kristel Zaman
SourceWater Environment & Technolology
Project IDWET2018_24
SubjectPumps;
Document typeMagazine article
PublisherWater Environment Federation
Print publication date Jul 2018
Volume / Issue30 / 7
Content sourceWE&T Magazine
First / last page(s)32 - 37
Copyright2018
Word count2,646
Subject keywordsenergy efficiencysingle-phasethree-phasecostsmaintenance

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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
Single-phase vs. three-phase power
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
With only one phase of power, voltage drops to zero three times during each cycle. With the peaks and dips in voltage, power is not delivered at a constant rate. This is like trying to move a canoe with only one oar: Progress is jagged, moving forward only when the oar is in the water, and coasting or stopping between strokes. (See Figure 1, p. 34.)
PublisherWater Environment Federation
Copyright2018
Word count302
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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
But what if single phase power is all you have available?
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
Most residential areas and even some commercial zones lack access to three-phase power. Bringing three-phase power in typically is prohibitively expensive. Especially for a water or wastewater utility, which may cover a vast area, requiring many smaller pumping stations scattered throughout the service area to run three-phase power at remote locations is cost prohibitive.
PublisherWater Environment Federation
Copyright2018
Word count288
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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
How does that translate to field operation?
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
Lumberton, Texas, provides an example of how VFDs can work in the field. Robb Starr, operations manager of the Lumberton Municipal Utility District and his staff began exploring VFD conversion of single-phase to three-phase power in 1998. They first began with beta testing a VFD conversion system on a pump station for a commercial client.
PublisherWater Environment Federation
Copyright2018
Word count217
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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
Cleaner power, motor protection and control that resolved the pump binding – eliminating resets
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
During the beta test, which lasted 3 to 4 years, the operation was much nicer. To address the binding issue, the district staff determined that three-phase power could reverse the motor at the end of the cycle. This would free the cutter so that it was ready to start the next cycle without material being caught inside. Initially, Starr and his operators set this up as a manual function with a...
PublisherWater Environment Federation
Copyright2018
Word count438
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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
Set it and forget it
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
Working through its service area, the Lumberton Municipal Utility District systematically replaced its grinder pumps with VFD-equipped grinder pumps to convert to three-phase power. Using what they had learned about reversal of the pumping at the end of a run cycle from the beta testing, the team programmed the VFDs to automatically reverse the flow. This simple programming option eliminated...
PublisherWater Environment Federation
Copyright2018
Word count125
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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
Pricing VFDs
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
Starr readily admits that 20 years ago using VFDs for smaller pump stations wasn’t economically viable based on energy savings or motor maintenance costs alone. In 2003, when Lumberton began to make the transition for the majority its 700 smaller pump stations, the district was able to afford it in part due to discounts they negotiated as part of the testing as well as volume discounts....
PublisherWater Environment Federation
Copyright2018
Word count364
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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
Motor protection, enhanced performance and longer life
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
“Unsurpassed motor protection!” exclaimed Robb Starr when asked the best benefit of switching to VFDs for phase conversion. But how does a VFD provide this protection, as well as the many other features that make it worth switching? VFDs have several programmable variables that provide customization, control, and motor protection. Even small VFDs may have 50 or more of these...
PublisherWater Environment Federation
Copyright2018
Word count733
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Description: Understanding variable frequency drives: Powering efficiencies for small pumps...
Multiple benefits, energy savings, increased equipment life, reliability, and cost savings – improvements worth considering
Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion
Whatever the goal — increased reliability, enhanced performance, longer motor and pump life, fewer service calls, reduced energy consumption, or a cost-effective retrofit — installing a VFD for phase conversion is an option worth evaluating. The benefits are many, and with the advances in compact size, capability, and cost reduction, VFDs are an excellent choice even for small pump...
PublisherWater Environment Federation
Copyright2018
Word count88
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Understanding variable frequency drives: Powering efficiencies for small pumps through phase conversion