Cascade Controller Option
Standard Cascade
Controller Setup
due to flow. For this system configuration, or
for two setpoint PID control, see
Alternative
Programming
at the end of this chapter.
Description of choice:
Set the desired feedback minimum within the
programmed minimum and maximum in Quick Menu
items 014 and 015. The process unit is selected
in Quick menu item 013,
Process Units
.
NB!:
Factory setting is for a single 4 - 20 mA current
signal transmitter for process feedback. In
all other cases, see instructions in Chapter
10,
Feedback Transmitter Wiring
.
Quick Menu 029 Par. 419 Setpoint 2
(SETPOINT 2)
Value:
Feedback Min. to Feedback Max.
✭
0.000
Function:
The default feedback process is used when a pressure
feedback signal is measured at the outlet of the
pumps. The cascade controller uses the feedback to
estimate the setpoint required at various rates of flow.
All other reference signals are ignored. Setpoint 2 is
the maximum pressure required when the system is
running with all pumps at full capacity. A theoretical
value calculates pressure loss in the system under
maximum load. The controller adjusts the loading
based upon the number of pumps in
The range is determined by Quick Menu item 014
(parameter 413,
Minimum Feedback
) and Quick Menu
item 05 (parameter 414,
Maximum Feedback
).
When the pressure feedback signal originates at
the far end of the system, the drive does not
need to compensate for system pressure changes
due to flow. For this system configuration, or for
two setpoint PID control, or for water pumping
systems where the feedback signal is measured
across the outlet of the pumps, see
Alternative
Programming
at the end of this chapter.
Description of choice:
Set the desired feedback maximum within the
programmed minimum and maximum in Quick Menu
items 014 and 015. The process unit is selected
in Quick menu item 013,
Process Units
. In a water
supply system with little leakage, the difference
between Setpoint 1 (set in Quick Menu item 028) and
Setpoint 2 is typically around 10% to 15%.
Quick Menu 030 Par. 721 De-stage timer
(DESTAGE TIME)
Value:
0 - 300 sec. (301= OFF)
✭
15 sec.
Function:
The de-stage timer starts when the adjustable speed
pump is running a minimum speed with one or more
constant speed pumps in operation and system
requirements satisfied. In this situation, the adjustable
speed pump contributes little to the system. When
the programmed value of the timer expires, a fixed
speed pump is destaged and the adjustable speed
pump accelerated to maintain system requirement.
This saves energy and avoids dead head water
circulation within the adjustable speed pump.
Description of choice:
Set the de-stage timer interval. When sleep mode is
activated, ensure the interval is set lower or equal to
the value of the sleep mode timer (parameter 403).
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43