Feature Drives, motors & controls Taking command of the situation
Variable speed drives from Control Techniques have helped slash energy bills by over $2,000 a month, reduce downtime and extend equipment life at a US food distribution centre. The savings have been achieved due to lower fan motor and compressor energy usage and better control of the site’s freezer/cooler systems
T
he food distribution centre facil- ity is owned by one of the largest suppliers to the food service industry, and stores large quanti- ties of foodstuffs in freezer and cooler boxes ready for regional distribution. Prior to Emerson’s upgrade work, each freezer and cooler box was controlled by a circuit with its own compressor, condenser and evaporator(s). These were in turn controlled by individual mechanical thermostats and defrost time clocks.
The customer was having an issue with the defrost performance of the evaporators on the freezers: all of the evaporators needed to be defrosted at the same time, but the freezer con- densing units had individual mechan- ical defrost clocks that would not remain synchronised once set. Key Mechanical, the customer’s refrigeration contractor, approached Emerson for help with finding a solu- tion. Working alongside Emerson Retail Solutions, an Emerson Climate Technologies company, Control Techniques and Key Mechanical pro-
posed new control systems for the cir- cuits on the freezer and cooler boxes. The solution involved the installation of 21 Commander HSK variable fre- quency drives from Control Techniques and two Einstein E2 RX400 refrigeration controllers from Emerson Retail Solutions which con- trol existing Copeland semi hermetic compressors from Emerson Climate Technologies.
The new system enabled the cus- tomer to control the speed of each Copeland compressor, and the con- denser and evaporator fan motors. The RX400 controllers are programmed to control temperature, defrost cycles and frequency drive output for floating head pressure, floating suction pres- sure and evaporator fan motor speed during the normal refrigeration cycle. Of the 21 HSK drives, seven control the Copeland compressors, seven control the condensers and seven control the evaporators.
When the new system was installed, the result was a reduction in electric- ity consumption of 250,676 kWhr per
The drive retro-fit meant the rooftop condenser equip- ment did not need to be replaced
year, providing a saving of over $2,000 a month on the customer’s energy bill. Energy savings were possible due to reduced fan motor energy consump- tion as a result of improved fan man- agement, and a reduction in compressor energy consumption due to reduced compression ratios. Additionally, downtime has been slashed and overall equipment life has been extended due to better tempera- ture control and defrost management as well as reduced compressor cycling. Ron Kvinge, branch manager for Key Mechanical Portland said: “The only option for the customer, other than a drive retrofit was replacing all the rooftop equipment for the plant – which would obviously have been a much larger capital expense. The solu- tion suggested by Key Mechanical resulted in better control of the freezer/cooler systems, major energy savings and less wear and tear on equipment.” David Yankaskas, regional sales manager at Control Techniques, said “Without Emerson’s proprietary suc- tion and head pressure controller tech- nology, the energy and cost savings for our customer could not have been achieved.
Better control of walk-in food freez- ers results in
energy savings and less wear and tear on equipment
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“From the perspective of day to day operations, controlling the HSK drives through the two Einstein RX400 con- trollers is obviously much simpler than having to programme and moni- tor all 21 of them individually. Overall, the Emerson/Key Mechanical solution is functioning extremely well and is saving the customer over $2,000 dollars a month!”
Control Techniques T: +44 (0)1686 612000
www.controltechniques.com
Enter 212 WINTER 2013 Irish Manufacturing
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