Abstract: An adjustable frequency pump control system (10) that is primarily designed for use in commercial pool filtration systems. The system (10) automatically selects one of three operating speeds that control the speed of a motor that operates a circulation pump (62). The system (10) includes a programmed logic control (PLC) (42) that is activated upon the application of select mode signal (31), a mode timing signal (35), a line pressure signal (37), a circulation pump-run signal (39) and a backwash signal (41). The output of the PLC (42) is a frequency set signal (17) that is applied to an adjustable frequency drive (AFD) (18). From the output of the AFD (18) a motor speed control signal is produced that is applied to the motor that operates the circulation pump (62). The speed of the circulation pump (12) is governed by the frequency of the motor speed control signal, wherein the frequency is determined by the motor speed that is applicable to a particular design point of the pump's filtration cycle.

Abstract: An adjustable frequency pump control system (10) that is primarily designed for use in commercial pool filtration systems. The system (10) automatically selects one of three operating speeds that control the speed of a motor that operates a circulation pump (62). The system (10) includes a programmed logic control (PLC) (42) that is activated upon the application of select mode signal (31), a mode timing signal (35), a line pressure signal (37), a circulation pump-run signal (39) and a backwash signal (41). The output of the PLC (42) is a frequency set signal (17) that is applied to an adjustable frequency drive (AFD) (18). From the output of the AFD (18) a motor speed control signal is produced that is applied to the motor that operates the circulation pump (62). The speed of the circulation pump (12) is governed by the frequency of the motor speed control signal, wherein the frequency is determined by the motor speed that is applicable to a particular design point of the pump's filtration cycle.