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Three rules for installing refrigerator compressors

20 December, 2022

Almost all food and beverage plants need cooling and refrigeration at some point in the process, whether for raw ingredients or finished products. George Dodwell, ABB area sales manager for drives, explains what to consider when installing VSDs for refrigeration applications.

Industrial cooling and refrigeration systems can consume a lot of energy, not least because they often run continuously. Screw and reciprocating compressors also need high overload capabilities. A variable-speed drive (VSD) is a natural fit for these applications because drives can reduce energy usage significantly throughout their lifetime, allow better control over temperature to reflect needs at a given time, and reduce equipment wear.

Here are three things to bear in mind when installing, replacing or upgrading drives for refrigeration applications:

Understand the compressor’s overload requirements Depending on the type of compressor, overload requirements may be much higher than for other applications. Compressing air needs a lot of mechanical inertia, and thus a high starting current. This has implications for the kind of drive to use, because the overload requirement can be up to 160%. In some cases, this will require a heavy-duty drive. Many general-purpose drives (such as ABB’s ACS580) will have heavy- and normal-duty ratings, however you may still need to oversize your drive to handle both the application’s power requirement and the overload current. For example, an 11kW compressor application with 160% overload will require a drive rated at 30kW or more.

Check mechanical infrastructure Before the advent of VSDs, cooling power was controlled using valves, louvres and dampers. A VSD can instead provide constant and precise pressure and flow control automatically, regardless of the conditions, and without the need for any mechanical vents or other devices. After a drive has been installed, these mechanical items are sometimes not only left in place, but left fully or partially open/closed. This is extremely inefficient, because everything a damper is stopping, and/or anything that is escaping through a vent, is simply wasted energy. After installing a drive, check the mechanical infrastructure and fully open/close, or remove, any unnecessary mechanical controls to allow the drive to operate with maximum efficiency.

Use a trusted provider For the reasons outlined above, and many others, refrigeration is not like other applications. To achieve the best outcome for your facility, you need to work with a service provider, installer or OEM who has knowledge and experience of the F&B industry, as well as compressor drive requirements, where drives should be installed, and how they should be used.

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