ABB ACH550-01 User Manual page 112

7. Pump alternation
This application macro is intended for pump alternation
applications, usually used in booster stations in buildings. The
pressure in the network is adjusted by changing the speed of the
pump according to the signal received from the pressure
transducer and adding auxiliary pumps directly on-line when
needed. By default, this macro can use one auxiliary pump. To
use more auxiliary pumps, refer to parameter
CONTROL. See the figure below.
When process PI(D) is used in the AUTO mode, the feedback
signal must be connected to analog input 2 (AI2) and the START
command is given with digital input 1 (DI1). By default, the
setpoint is set from the control panel (operator keypad), but it
can also be given through the analog input 1. Process PI(D)
must be commissioned and adjusted with parameters
40: PROCESS PID SET
(recommended).
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ACH550 User's Manual
1) or using the PID control assistant
Application macros and wiring
Group 81: PFA
(Group