Parameters 25-** Cascade Controller - Danfoss VLT AQUA Drive FC 202 Programming Manual

Parameter Description

3.22 Parameters 25-** Cascade Controller

Parameters for configuring the basic cascade controller for sequence control of multiple pumps. For a more application-
oriented description and wiring examples, see Application Examples, Cascade Controller in the design guide.
For information on using the advanced features of the cascade controller options, see chapter 3.24 Parameters 27-** Cascade
CTL Option.
To configure the cascade controller to the actual system and the required control strategy, follow the sequence starting with
parameter group 25-0* System Settings and next parameter group 25-5* Alternation Settings. These parameters can normally be
set in advance.
Parameters in parameter groups 25-2* Bandwidth Settings and 25-4* Staging Settings often depend on the dynamic of the
system and final adjustment to be done at the commissioning of the plant.
NOTICE
The cascade controller is supposed to operate in closed loop controlled by the built-in PI controller ([3] closed loop
selected in parameter 1-00 Configuration Mode). If [0] open loop is selected in parameter 1-00 Configuration Mode, all
fixed speed pumps are destaged, but the variable speed pump is still controlled by the frequency converter, now as an
open-loop configuration:
Con guration mode (P 1-00):
Cascade controller (P 25-00):
Motor start (P 25-02):
Pump cycling (P 25-04):
Fixed lead pump (P 25-05):
Number of pumps (P 25-06):
Lead pump alternation (P 25-50):
Alternation Event (P 25-51):
Alt. if capacity<50% (P 25-55):
Staging mode at alternation (P 25-56):
Illustration 3.79 Cascade Controller Sample Set-up
MG20OB02
Programming Guide
Con g. of cascade controller
Open Loop Closed Loop
Disabled Enabled
Direct on line
Disabled
No
2
O
At
staging
command
External
Disabled
Slow
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Soft Starter
Enabled
Yes
2 3
At At staging
or
command
Alt. timer
Sleep
interval
mode
P 25-52
Enabled
Quick
3 3
Prede ned
timer
P 25-54
207