Modicon M171 M172 Plc For Hvac And Pumping Applications Page 2-6 Solutions overview

2 1 3 4 5 6 7 8 9 10 2/6 Compressor management Description The compressor management function controls a combination of fixed and variable speed compressors to maintain a constant pressure or water temperature in a chiller system. Benefits Performance > Maintains the required temperature or pressure by controlling: > the capacity of the compressors in a system with a variable speed drive > or the number of compressors Response > Makes the system energy efficient by controlling compressor capacity prior to switching compressors on/off > Facilitates smooth operation by monitoring compressor availability and changing over to the next available compressor if an error is detected Operating principle The main objective of this function block is to perform control and switching of multiple compressors to maintain a pre-defined temperature or pressure in a chiller system. The temperature and pressure are measured through sensors while the setpoints are entered through the HMI. The function uses intelligent algorithms to manage switching by assigning priorities to the compressors based on availability and energy optimization. Characteristics Main characteristics: > Controls scroll, screw, or reciprocating compressors > Balances operating hours based on first in first out (FIFO), last in first out (LIFO), or runtime algorithms > Supports minimum on timer, minimum off timer, and minimum cycle timer to help prevent frequent compressor switching > Supports timers to help prevent frequent compressor switching > Oil recovery function helps prevent compressor damage during partial load conditions > Helps eliminate resonance frequencies during compressor operation, thereby helping to increase compressor lifetime and reduce noise > Supports up to 8 compressors per refrigerant circuit > Allows variable speed drive regulation > Supports heating or cooling mode Typical applications > Air and water cooled chillers > Heat pumps > Rooftop units > Compressor racks Presentation Solutions overview Application solutions for HVAC Related functions: Compressor management

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