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Savings Can Be Realized Through Variable Frequency Drives

By admin | In AviCarCare | on November 15, 2009

WRITTEN By Wendi Winters

There are more benefits than a lowered electricity bill.

Screen shot 2013-12-15 at 2.05.42 PMWe’Ve Retrofitted All Our Washes And We Won’T Build A Wash Without One,” Declared Chip Hackett, Owner Of Four Exterior Express Ultra Car Wash Locations In The Atlanta, Georgia, Area. Clearly, Chip hackett is hooked on vFDs—variable Frequency Drives. “We got into the business five years ago. We focused on building the business, but we’ve been focusing lately on the expense side. We got the soaps and water under control, but the big gaping hole was in electricity and power management.”

All of the washes offer a low-priced exterior wash and a free self-vacuum service. Two more are under construction. Some sites have up to 35 vacuums, and on a busy day 120 cars will pass through the tunnels each hour. Just like the vacuums, the tunnel blowers are going non-stop when volume is high. The vacuums are sucking up more than just dirt. along with the blowers, they are a major energy drain, sucking up hackett’s profits. With the help of steve Tucker of autovac Industrial vacuum & air systems in san Diego, California, hackett has found a way to dramatically lower his monthly power bills.

Top: The vfds and motor control center for a new wash in Mobile, AL. The cabinet on the left was manufactured by Autovac and contains their VacuumIQ vfds. The cabinet on the right is a custom mcc manufactured by Rockwell Automation for Smart Start RA.

It contains soft starts for all motors under 5hp and VFDs on all motors over 5hp. Center: The inside of the custom motor control center with a close-up on the 70 hp vfd that controls the blowers. This vfd provides the flexibility to change blower speed by wash package, idle the blowers between cars, change blower speed based on outside air temperature and operate blowers at an efficient level, all of which leads to significant (30%+) savings in power and dramatically decreased peak demand.

Bottom: The outside of the custom mcc by Rockwell Automation/Smart Start RA.

“We have had good success with vFDs,” he said. “We have installed them on our vacuum producers at two of our locations. The vFDs monitor the pressure within the vacuum system and adjust the speed of the motors accordingly to provide the right amount of suction based on the number of users. as a result, we are able to provide suction on demand.” at full speed, a 25 hP motor operates at 60 hz. In the case of hackett’s ultra Wash operations, when all hoses are hung up, the vFD reduces the speed of the motor to around 40 to 42 hz. This is two-thirds of capacity and what is needed to produce enough suction for one user.

“The key here is that at 40 to 42 hz, the power consumption is only 32%, compared to the power used at 60 hz or full speed,” he explained. “as each hose is dropped, the vFD ramps up the motor hZ until it reaches 60 hz, when all hoses are dropped.”

Bottom line, hackett and Tucker installed four vFDs at one location on 25 hP vacuum producers. There are several ways to measure the results. one factor that skews the results is there are usually varying car counts each month. however, at hackett’s ultra Car Wash locations where the vFD system provides power on demand by constantly communicating with all the vacuums and blowers, peak KW has been reduced 15-20% since its installation. Electric companies bill based on peak demand. The “smart” vFDs that autovac installs can cut peak demand usage, providing additional savings. Moreover, hackett said, overall kilowatt use has been reduced by a greater percentage, and, where the rubber meets the road, the daily electricity costs at the ultra Car Wash sites with smart vFDs have been reduced about 15- 20% on a year-over-year basis. “But keep in mind,” hackett added, “we have been having double-digit rate increases, so the apples-to-apples savings have been much greater.”
he noted, “The up-front cost can be difficult to swallow. however, when you consider the cost of actually operating the vacuums over the long run, the return associated with the initial investment makes it an easy decision.” Tucker said wash owners should also scrutinize their rate plans. “The correct rate plan can save you up to $1,000 per month at each location.” hackett is so pleased with his smart vFDs that he wants to preach the vFD gospel. “We’re setting up a consulting company, in partnership with steve at autovac, to explain to wash owners why vFDs are a good investment.”
Jimmy Belanger is the owner of smart start Ra, located in northville, Michigan. according to his Web site, the company was “founded by car washers to help car washers understand and benefit from advanced motor control technology without breaking the bank to enjoy its benefits.”

From wet down to shut down, the company’s technology is designed to save carwash operators money throughout the business day using intelligent motor control. These controls eliminate peak demand spikes and maximize electrical consumption efficiency without degrading equipment performance, service quality or profit margins.Wash Trends Magazine spoke to him recently for his opinion on vFDs—variable Frequency Drives. We asked him to explain what a vFD is in plain, layman’s English that would be understandable to both a multi- unit franchise owner and the part-time manager of a single touchless tunnel wash.
“I own a company that is putting vFDs into application and we’re teaching car wash owners how to do vFDs,” Belanger said. he added the following written explanation.
“a vFD is like a big dimmer switch for motors,” he said. “It can increase or decrease motor speed as needed depending on the work required of the motor. There is no sense running a motor flat out 100% of the time if only 50% of its capacity is required or 100% of its capacity is only required 50% of the time.”
“The affinity Laws state that reducing the speed, even slightly, results in a large reduction in required horsepower. This adds up to significant energy savings. For example, at 50% speed, the horsepower required is only 12.5% (0.53 = 0.125 = 12.5%). For a 50-hp motor, this means only 6.25 hp is required. It would actually cost less to run two 50 hp motors at 50% speed than it would to run one 50 hp motor at 100% speed. “vFD technology is a great technology for carwashes but misunderstood and misapplied. If misapplied, the additional acquisition cost of the technology delivers zero RoI (return on investment). anyone who has had a bad experience with vFD technology in the carwash industry is due to inexperienced suppliers misapplying the technology.
“To benefit from vFD motor control, the variable frequency drive must be programmed to change the speed of the motor when full speed is not required. an excellent place to start to look for energy savings from vFD technology is Fan applications; at the carwash that means vacuums and dryers.
“For vacuums, the objective is to provide enough suction pressure to satisfy customers. Most systems are designed for a given number of vacuum drops, or vacuum positions. using a simple motor starter, the vacuum motor operates at 100% speed every second that it is on such that 100% maximum pressure is provided to the first drop in use with a subsequent decrease in pressure until all the vacuum positions are in use. With a vFD, the operator can provide a consistent vacuum suction pressure with the first to the last position occupied by obtaining data from a sensing device, such as a pressure transducer, to automatically adjust its speed to maintain a certain pressure or flow. If the fan speed can be reduced to 75% of rated speed, power consumption can be reduced by as much as 42% of rated power. The savings comes from running the vacuum motor at the minimum acceptable speed for satisfactory suction with the first position occupied and increasing speed with demand at subsequent positions, matching demand with increase in fan speed.
“For dryers, the potential savings come from slowing the motors down when no vehicle is present. simple motor starters keep motors running flat out, waiting
for vehicles and in between vehicles. It is simple, with a vFD, to use the tunnel
controller to reduce dryer fan motor speeds when no vehicle is present.”
In addition to energy savings, part of the interest in vFDs has been spurred by the federal government. The u.s. Energy Policy act of 2002 (with amendments in 2005) offers tax incentives for energy- saving measures that it annotates. To realize the savings, a business owner has to have a viable method to monitor and measure his or her energy usage. The benefits of the EP act are increasing the interest in software that can manage an owner’s use of power, water, chemicals and supplies.
according to statistics supplied by the u.s. Department of Energy to Flex Your Power, California’s statewide energy efficiency marketing and outreach campaign: “Motor systems consume as much as 60% of all electricity in the united states; half of this electricity is used by the industrial sector alone. Motor applications vary as widely as the businesses they serve, but common ones include fans, pumps, compressors, and conveyance. around 70% of the total electricity used by all u.s. manufacturers powers motor systems.”
Flex Your Power’s statistics for manufacturers can be similarly applied to carwash dryers, vacuums and other equipment that can benefit from vFDs and soft-start applications.
“a well-designed and well-maintained motor system can reach 90% efficiency— meaning that 90% of the input energy gets converted to useful work. unfortunately, only a small portion of the u.s. motor inventory falls into this category—the majority of motors in use are highly inefficient. The good news, though, is that as older motors are retired, opportunities arise to improve these statistics with newer, more efficient technology,” states Flex Your Power’s Web site entry on Energy use Basics. The site adds: “The u.s. Department of Energy (DoE) estimates that u.s. manufacturers could cost- effectively reduce motor-related energy use by 11 to 18%, yielding cumulative annual cost savings of up to $5.8 billion. similarly, the american Council for an Energy-Efficient Economy (aCEEE) estimates that optimization of electric motor performance can save as much as 25% of total u.s. electricity use. For individual manufacturers, motor-drive optimization potentially saves as much as 50% of motor energy use…”
gary Dennis owns four ultra Car Washes in the atlanta, georgia, and Mobile, alabama, region, plus two new washes are under construction. he’s developed some cost-and energy-savings data from vFD use on his vacuums.
“We’re doing several tests, in different ways,” he explained. “When measuring results, you have to do it several ways. Issue 1: Electric costs are fixed but variable depending upon the number of cars washed. Issue 2: When comparing your present electrical use to previous periods, the kilowatt rates are increasing. ours went up 30% in two years.”
Recently, he upgraded old equipment and simultaneously installed new equipment.
When vFDs were installed in two places on his vacuum equipment, there was a 15% reduction in electrical use. he also updated his vFD software to “go from discrete to continuous movements. Before I installed the vFD, the equipment could only move in three or four levels – 50%, 70%, 90% and 100%. now, it moves continuously up and down in fine 1% increments, instead of big jumps.”
In analyzing his energy costs, Dennis learned there were different rate plans offered by his power provider. “some areas have only one company they can deal with; other places you’ve got several providers to choose from,” he observed.
he asked for a different rate plan and was pleased when he received a lower rate. his upgrades and installations began
in august 2008. Dennis has collected four months’ data. he noticed a 15 to 20% reduction in energy usage—in addition to the new rate plan he negotiated with his supplier. “I’m looking at average daily electric costs divided by the number of days covered by a particular bill. some will be for 28 days, others 33 days.”
The savings are real. he said, “It’s not what I paid for electricity in the past, but what I would have paid in the future that is important. These three moves—upgrading old equipment, installing vFDs and negotiating a better rate—will probably save us $35,000 a year in energy costs.”
“These are permanent savings,” he emphasized. “We could argue our cash flow is going to improve $35,000 each year. We’ve created $175,000 of business value each year by making these changes.”

Wendi Winters is a freelance writer who lives in Annapolis, Maryland.

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