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 Chapter Application Examples, item Basic Cascade Controller in the Design
Guide.
To configure the Cascade Controller to the actual system and the desired control strategy, it is recommended to follow the
below sequence, starting with parameter group 25-0* System Settings and next parameter group 25-5* Alternation Settings.
These parameter can normally be set in advance.
Parameters in 25-2* Bandwidth Settings and 25-4* Staging Settings, will often be dependent 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 (Closed Loop
selected in parameter 1-00 Configuration Mode). If Open Loop is selected in parameter 1-00 Configuration Mode, all fixed
speed pumps will be destaged, but the variable speed pump will still be 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 3.71 Cascade Controller Sample Set-up
MG20O702
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
Danfoss A/S © Rev. 2014-01-21 All rights reserved.
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
173