Operating instructions

25-23 SBW Staging Delay
Range: Function:
15
s
*
[1 -
3000
s]
Immediate staging of a fixed speed pump is not
desirable when a momentary pressure drop in the
system exceeds the Staging Bandwidth (SBW).
Staging is delayed by the length of time program-
med. If the pressure increases to within the SBW
before the timer has elapsed, the timer is reset.
25-24 SBW Destaging Delay
Range: Function:
15
s
*
[0 -
3000
s]
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 program-
med. If the pressure decreases to within the SBW
before the timer has elapsed, the timer is reset.
175ZA671.10
SB W destage dela y
SB W
SB W
S etpoin t
25-25 OBW Time
Range: Function:
10
s
*
[0 -
300 s]
Staging a fixed speed pump creates a momentary
pressure peak in the system, which might exceed
the Override Bandwidth (OBW). It is not desirable to
destage a pump in response to a staging pressure
peak. The OBW Time can be programmed to prevent
staging until the system pressure has stabilized and
normal control established. Set the timer to a value
that allows the system to stabilize after staging. The
10 second factory setting is appropriate in most
applications. In highly dynamic systems, a shorter
time may be desirable.
25-26 Destage At No-Flow
Option: Function:
The Destage at No-Flow parameter ensures that
when a no-flow situation occurs, the fixed speed
pumps will be destaged one-by-one until the no-
flow signal disappears. This requires that No Flow
Detection is active. See parameter group 22-2*.
If Destage at No-Flow is disabled the Cascade
Controller does not change the normal behavior of
the system.
[0]
* Disabled
[1] Enabled
25-27 Stage Function
Option: Function:
If the Stage Function is set to Disabled [0],
par. 25-28 Stage Function Time will not be activated.
[0] Disabled
[1]
* Enabled
25-28 Stage Function Time
Range: Function:
15 s * [0 -
300 s]
The Stage Function Time is programmed to avoid
frequent staging of the fixed speed pumps. The
Stage Function Time starts if it is Enabled [1] by
par. 25-27 Stage Function, and when the variable
speed pump is running at Motor Speed High Limit,
par. 4-13 Motor Speed High Limit [RPM] or
par. 4-14 Motor Speed High Limit [Hz], with at least
one fixed speed pump in the stop position. When
the programmed value of the timer expires, a fixed
speed pump is staged.
Parameter Description
VLT
®
HVAC Drive Programming Guide
170 MG.11.CA.02 - VLT
®
is a registered Danfoss trademark
3
3