Magazine article Parks & Recreation

Variable Frequency Drives in the Aquatics Industry

Magazine article Parks & Recreation

Variable Frequency Drives in the Aquatics Industry

Article excerpt

Today there are approximately 300,000 commercial pools in the United States, and pumps, run by electrical motors, are relied on to keep drained pool water circulating throughout the system and back into the pool. The average size of a commercial pump motor is approximately 10 horse power, and in many cases, they operate 24 hours a day, seven days a week, consuming a whopping 2,250 megawatts of electricity. That's the equivalent of the amount of electricity produced in approximately 4.5 U.S. power plants annually.

Variable Frequency Drives (VFDs) offer pool operators an opportunity not only to conserve energy, but also to realize big savings for their agencies' budgets by reducing energy expenses. VFDs slow down pool pump speeds during low use times of operation. Specifically, they reduce the power being used by the pump's electric motors. Rich Young, managing editor of the sixth revised edition of the Aquatics Facility Operator Manual, explains, "Without getting too technical about how VFDs actually work, the 'magic' of VFDs is the conversion of alternating or 'dirty' current (AC) into direct current (DC), adjusting the DC into a smooth or constant current, then converting the DC back to "clean" AC power. This allows for the adjustment of the pump motor 'hertz' that will provide the pump RPM adjustment." Slowing down all commercial pool pump speeds in the United States by 24 percent can, potentially, reduce the required power plant use from 4.5 average plants to two. In other words, VFDs are to the pool industry what hybrid cars are to the auto industry: an energy-saving solution that only uses the power you need when you need it.

The manufacturing and usage of VFDs has been prominent in Europe for more than three decades. It wasn't until the 1990s, that VFDs started to gain greater popularity here in the United States. Prior to this, VFDs had been primarily used in heavy industrial applications. Currently, a third of the world's electrical energy is being consumed by electric motors on pumps and fan compressor applications, with the U.S. aquatic industry consumption referenced above.

While, in theory, VFDs are a great cost- and energy-saving solution, they ARE NOT for every facility. Before installing a VFD, an energy audit, along with a mechanical and operational assessment of the system must be done. Always get a copy of your state-approved operational data and compare your pool and facility data against it to ensure accuracy and avoid being noncompliant.

Many facilities cannot reduce the speed of their motor because of the gallons per minute (GPM) flow rate dictated by their local health department. …

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