User`s manual

ACH550-01 User's Manual

96 Application macros and wiring

3. Return fan

This application macro is for return fan applications where the

return fan takes air out of the room according to the signals

received from the transducer. See the figure below.

When using a direct speed reference in the AUTO mode, the

speed reference must be connected to analogue input 1 (AI1)

and the START command is given with digital input 1 (DI1). In

the HAND/OFF mode, the speed reference and START

command are given through the control panel (operator keypad).

If process PI(D) is used, the feedback signal must be connected

to analogue input 2 (AI2). By default, the setpoint is set from the

control panel, but it can also be changed to analogue input 1.

Process PI(D) must be commissioned and adjusted with

parameters (Group 40: PROCESS PID SET 1) or using the PID

control assistant (recommended).