ABB ACS560 Firmware Manual page 138

138 Control macros
Example of a 3-pump constant pressure water supply application:
Pump 1 - connected to Motor 1
Pump 2 - connected to Motor 2
Pump 3 - connected to Motor 3
Flow consumption versus pump status
Consumption
Low
Normal
↓
Normal
VSD
DOL
Off
Pump 1
VSD
DOL
Off
VSD
DOL
Variable Speed Drive (yellow colour connecting line in the figure).
Controlled by drive, tuning the output speed according to PID control.
Direct On Line (red colour connecting line in the figure). Pump is running
at fixed motor nominal speed.
Off-line. Pump stops.
Pump 2
Off
VSD
DOL
DOL
VSD
Pump 3
Off
Off
VSD
Off
Off