ABB ACS560 Firmware Manual page 126

126 Control macros
Example of a 3-pump constant pressure water supply application:
Pump 1 - connected to VSD motor
Pump 2 - connected to auxiliary motor 1
Pump 3 - connected to auxiliary motor 2
Flow consumption versus pump status
Consumption
Low
↓
High
↓
Low
VSD
DOL
Off
Pump 1
VSD
VSD
VSD
VSD
VSD
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
DOL
DOL
DOL
Off
Pump 3
Off
Off
DOL
Off
Off