Instruction manual

Cascade Controller Option
■ Alternate programming
In water supply systems, it is often impractical to
placeapressuresensoratthefarendofthesystem.
In HVAC and other applications, however, it is often
possible to place the pressure sensor(s) at the farthest
significant load and measure actual pressure in the
system. In these cases, the cascade option can use
the drive’s PID controller to respond to system changes
as programmed. Pumps or fans are staged on and
off in response to the system feedback signal.
The most common setup for feedback response is with
a single transmitter located at the farthest significant
load in the system. Programming the cascade
controller option in this manner is described below. It
is also possible for the PID to accept two feedback
signals, making two-zone regulation available. For two
feedback control, and for additional setting options,
see the Operating Instructions for your AFD series.
Setup for feedback response is with a single transmitter
located at the farthest significant load in the system
requires programming parameter 417, Feedback
Function, and parameter 418, Setpoint 1. Parameter
417, Feedback Function, is only accessible through the
Extended Menu. The Extended Menu is accessed by
pressing the [EXTEND. MENU] key on the drive control
panel. Parameter 418 may be accessed through either
the Extended Menu or as item 29 in the Quick Menu.
EXTENDED MENU Par. 417 Feedback Function
(2 FEEDBACK, CALC.)
Value:
Minimum (MINIMUM)
Maximum (MAXIMUM)
Sum (SUM)
Difference (DIFFERENCE)
Average (AVERAGE)
Two-zone minimum (2 ZONE MIN)
Two-zone maximum (2 ZONE MAX)
✭Virtual Control Curve (VIRTUAL CTRL CURVE)
Feedback 1 Only (FEEDBACK 1 ONLY)
Feedback 2 Only (FEEDBACK 2 ONLY)
Function:
This parameter sets the calculation method whenever a
system feedback signal is used, or when two feedback
signals (Setpoint 1 and Setpoint 2) are used.
Description of choice:
Set the feedback function to Maximum for
the drive to use Setpoint 1 as the maximum
reference signal for control.
Quick Menu 029 Par. 418 Setpoint 1
(SETPOINT 1)
Value:
Feedback Min. to Feedback Max.
✭ 0.000
Function:
Setpoint 1 is used to provide the setpoint reference
for one setpoint PID control or for the setpoint for
zone 1 in two setpoint PID control.
All other reference signals are ignored.
Description of choice:
Set the required value the system is to maintain
during normal operation. The value must be between
the minimum and maximum values set in Quick
Menu items 14 and 15 (parameter 413, Minimum
Feedback, and parameter 414, Maximum Feedback).
Setpoint 2, Quick Menu item 30, is not used in
one feedback signal applications.
MG.60.I5.22 - VLT is a registered Danfoss trademark
49
Standard Cascade
Controller Setup