Would you like to save thousands of dollars in electric utility costs and protect vital equipment while at the same time reducing your aquatics facility’s carbon footprint?
What if you could buy a piece of equipment that could do all this and more while giving you a return on your capital investment in less than a year? This may sound too good to be true, but — believe it or not — there is such a thing: variable frequency drives, or VFDs.
Traditionally, a device called a starter or mag start is installed on an electrical circuit to facilitate the starting and stopping of a pump motor. When a button is pushed or a lever switched, a pump motor instantly starts or stops. A VFD is installed in place of this starter. The VFD does not simply start and stop the pump motor; it actually controls the pump motor. This control is where the magic begins.
To help you better understand what a VFD can do, let’s explore some basic electrical theory.
In our homes and workplaces, most electrical devices are powered by AC (alternating current) circuits. A typical 120VAC, single-phase circuit found in our homes will carry voltage that looks like a wave when viewed on a device called an oscilloscope, which analyzes electrical signals. In electrical circuits in the United States, there are 60 of these cyclic undulations per second, hence the term 60 cycle or 60 Hertz (Hz). In other areas of the world, 50-Hz circuits are more common. The voltage carried on these circuits would have 50 “waves,” or cycles, per second.
Put another way, if we took a U.S.-made analog wall clock (one with hands) overseas on a trip, adapted it to the voltage difference and then plugged it in, we would find that the clock would run 10 percent slower on the 50-Hz circuit than on a 60-Hz circuit back in the U.S. This is because the electric motor that turns the hands of the clock spins at a rate directly related to the frequency of the power source.
Similarly, by changing the frequency of the waves in an electrical circuit, a VFD can slow down or speed up an electric motor that drives a pump. This capability of regulating pump speeds can replace the throttle valve to regulate flows in any waterfeature or filter system. This simple fact represents an opportunity to save thousands of dollars per year for any given facility because turning a motor slower controls flow more efficiently as it uses less electricity.
To better illustrate this potential savings, let’s look at two hypothetical examples. In the first, a typical large-scale, indoor waterpark saves nearly $50,000 annually in electrical energy costs by using VFD technology instead of standard throttle valves to modulate flow. Despite its smaller size, the indoor community recreation center typically realizes savings of more than $15,000 per year in electrical energy costs. Likewise, a large indoor waterpark in the Midwest recently reduced its electrical usage by 38 percent after switching to VFDs for its motor control needs.
In addition to energy savings, VFD technology offers facilities a host of other potential benefits. The ability to slowly speed the motor up and down allows a “soft” start or stop of water flow through a waterfeature, slide or filter system. This soft start/stop capability prevents water hammer, which can cause catastrophic physical damage to pipes and equipment.
Because VFD technology utilizes sophisticated technology to control motor speeds, additional motor protection features are standard with most VFDs. These features include over/under voltage protection, over-current protection, phase protection and over-temperature protection. These simple safeguards can prevent thousands of dollars in motor damage in the event of the all-too-common summertime brownouts or phase drops that occur during thunderstorms.
The best part is that the cost of VFDs has dropped significantly in recent years. Typical VFDs now range from $2,800 for a 15hp to $5,500 for a 40hp. In most cases, a return on the capital investment of VFDs can therefore be realized within a single year.
VFD technology can protect your equipment and make your facility more profitable. Best of all, using VFD drives for your pumps will help the environment as you do your part to minimize your facility’s carbon footprint. It truly is the green machine.