GE Industrial Solutions AF-600 FP Fan and Pump Drive (460V_575V 150HP and above) - Manual (Page 104)

NB!
If only two feedback signals are used, the feedback that is not to be used must be set to No Function
in par. CL-00 Feedback 1 Source, par. CL-03 Feedback 2 Source or par. CL-06 Feedback 3 Source. Note
that each setpoint reference will be the sum of its respective parameter value (par. CL-21 Setpoint 1,
par. CL-22 Setpoint 2 and par. CL-23 Setpoint 3) and any other references that are enabled (see par.
group C-30 and par. C-34).
NB!
Any unused feedback must be set to “No function” in its Feedback Source parameter: par. CL-00 Feedback 1 Source, par. CL-03 Feedback 2 Source or par.
CL-06 Feedback 3 Source.
The feedback resulting from the function selected in par. CL-20 Feedback Function will be used by the PID Controller to control the output frequency of the frequency
converter. This feedback can also be shown on the frequency converter’s display, be used to control a frequency converter's analog output, and be transmitted
over various serial communication protocols.
The frequency converter can be configured to handle multi zone applications. Two different multi zone applications are supported:
• Multi zone, single setpoint
• Multi zone, multi setpoint
The difference between the two is illustrated by the following examples:
Example 1 – Multi zone, single setpoint
In an office building, a VAV (variable air volume) AF-600 FP system must ensure a minimum pressure at selected VAV boxes. Due to the varying pressure losses
in each duct, the pressure at each VAV box cannot be assumed to be the same. The minimum pressure required is the same for all VAV boxes. This control method
can be set up by setting par. CL-20 Feedback Function to option [3], Minimum, and entering the desired pressure in par. CL-21 Setpoint 1. The PID Controller will
increase the speed of the fan if any one feedback is below the setpoint and decrease the speed of the fan if all feedbacks are above the setpoint.
Example 2 – Multi zone, multi setpoint
The previous example can be used to illustrate the use of multi zone, multi setpoint control. If the zones require different pressures for each VAV box, each setpoint
may be specified in par. CL-21 Setpoint 1, par. CL-22 Setpoint 2 and par. CL-23 Setpoint 3. By selecting Multi setpoint minimum, [5], in par. CL-20 Feedback
Function, the PID Controller will increase the speed of the fan if any one of the feedbacks is below its setpoint and decrease the speed of the fan if all feedbacks
are above their individual setpoints.
AF-600 FP High Power Operating Instructions
102
7