Danfoss Cascade Operating Instructions Manual page 40

Quick Menu 022 Par. 713 Staging Bandwidth %
(STAGING BANDW%)
Value:
1 - 100%
Function:
In cascade control systems, to avoid frequent
switching of fixed speed pumps, the desired system
pressure is typically kept within a bandwidth rather
than at a constant level. The staging bandwidth
(SBW) is programmed as a percentage of the setpoint
(desired pressure). For example, if the setpoint is 5
bar and the SBW set at 10%, a system pressure
between 4.5 and 5.5 bar is tolerated. No staging or
destaging will occur within this bandwidth.
Description of choice:
Set the staging bandwidth percentage to accomodate
system pressure fluctuation.
NB!:
Should the drive trip for any reason, the
cascade controller can continue operation
with the remaining C/S pumps or fans. It is
recommend, however, that the user consider a wider
bandwitdth for parameter 716, Override Bandwidth.
Otherwise, unnecessary staging could occure.
Quick Menu 023 Par. 714 SBW staging off time
(DESTAGING DELAY)
Value:
0 - 3000 sec.
Function:
Immediate destaging of a fixed speed pump is not
desirable when a momentary pressure increase in
the system that exceeds the staging bandwidth
(SBW). Destaging is delayed by the length of time
programmed. If the pressure decreases to within the
SBW before the timer has elapsed, the timer is reset.
40
Cascade Controller Option
10%
Description of choice:
Set the staging bandwidth off time delay. A delay
time of 30 seconds (factory setting) is sufficient
in most systems. When encountering frequent
staging, add to the delay time.
Quick Menu 024 Par. 715 SBW staging on time
(STAGING DELAY)
Value:
0 - 3000 sec.
Function:
Immediate staging of a fixed speed pump is not
desirable when a momentary pressure drop in
the system that exceeds the staging bandwidth
(SBW). Staging on is delayed by the length of time
programmed. If the pressure increases to within the
SBW before the timer has elapsed, the timer is reset.
30 sec.
Description of choice:
Set the staging on time delay. A delay time
of 30 seconds (factory setting) is sufficient in
most systems. When encountering frequent
staging, decease delay time.
MG.60.I3.02 - VLT is a registered Danfoss trademark
30 sec.