ABB VFDs Succeed Where Other Methods Fail – South Windsor Public Pools


Water and wastewater facilities are major uses of municipal operating budgets.  As municipalities face increasing budget restraints, the efficiency of these systems is imperative.  ABB variable frequency drives on process pumps and other equipment can be programmed to optimize efficiency based on plant loading.

With summer around the corner many towns are completing final maintenance and preparations to open their pool(s).  It is becoming more and more expensive to keep them safely running.  With a little help from a local company, the town of South Windsor combated the rising operating costs and made their pools more energy efficient…


The Challenge: Reducing Energy Consumption by Town Pools

South Windsor’s aquatic center houses three outdoor swimming pools, a children’s pool, a lap pool and the main pool.  The pools are open from June through August, and, on average, are used by 600 to 800 visitors per day during the hottest months.  Together the pools filter over a million gallons of water a day − the town’s largest operating expense.

Plant supervisor, Tim Friend, sought ways to reduce power usage when the pools were closed, while maintaining water purity.  To save energy, Friend and his team tried implementing several strategies with limited success. First they shut down the pumps each night, but that made it difficult to maintain water quality.  In an attempt to achieve the proper flow rate they throttled the valves, but the pumps drove up the amps on the single-speed motor back-flushing the equipment.


The Solution: Installing ABB Variable Frequency Drives

Friend knew there had to be a better way. He called Brian Robinson from Flow Tech, Inc. (FT) who helped him on previous projects.  Friend was already familiar with ABB Variable Frequency Drives (VFD) from past work with FT.  After analyzing the situation together, Friend and Robinson determined ABB VFDs could provide a major power savings.

The VFDs reduced the motor speed, but allowed the system to run with the valves completely open and achieve the full flow rate needed to run the filtration systems. FT provided bypass panels for the pumps so the pool engineers could bypass the VFDs if the need ever arose.  Pump speeds were set using on-board time clocks that initiated pre-set speeds for the VFDs.  Pumps were programmed to run at 90% when the pool was open at 60% for 12 hours each night.


The Results: Savings of 65,000 KWHs and $7,000 Annually

The addition of the VFDs saved 65,000 KWHs and $7,000. Not only did the system pay for itself in two seasons, but there was also less noise from the pumps.  “Now we can actually stand in the pump house and hear each other talk,” says Friend.  The drives eliminated the need for hard starts and stops.  For repairs and maintenance, engineers ramp the motors down, shut them off, perform their tasks, then ramp the speed up again, all without the high-demand and across-the-line surges from hard stops and starts.

“Flow Tech of South Windsor [has] come to the rescue many times to help keep the town’s various water pollution control facility pumps running.  More recently, [FT has] assisted town personnel with installing new pump drives at the VMP pool to help reduce electrical costs.”

           -Tim Friend, Town of South Windsor Department of Public Works

Your specific application and needs will determine the type of solutions and options most appropriate for ABB variable frequency drives.  We recommend you contact us to determine what is available to meet your needs and energy requirements.

1 Comment

  1. […] This rather technical article, which might interest if you’re into engineering, pumps and how to save energy around outdoor pools. […]

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