Alternate Programming - Danfoss Cascade Operating Instructions Manual

Alternate programming

In water supply systems, it is often impractical to
place a pressure sensor at the far end of the system.
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 VLT Operating Instructions.
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 28 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.
MG.60.I3.02 - VLT is a registered Danfoss trademark
Cascade Controller Option
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 028 Par. 418 Setpoint 1
(SETPOINT 1)
Value:
Feedback Min. to Feedback Max.
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 29, is not used in
one feedback signal applications.
0.000
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