Danfoss VLT FC 102 Programming Manual page 241

Parameter Descriptions
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
recommended 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 s factory
setting is appropriate in most
applications. In highly dynamic
systems, a shorter time may be
wanted.
OBW timer (27-25)
Illustration 3.80 OBW Time
25-26 Destage At No-Flow
Option: Function:
This parameter ensures that when a
no-flow situation occurs, the fixed-
speed pumps are destaged 1 by 1
until the no-flow signal disappears.
This requires that no-flow detection
is active. See parameter group 22-2*
No-Flow Detection.
If [0] Disabled is selected, the
cascade controller does not change
the normal behavior of the system.
[0] Disabled
*
[1] Enabled
M0010001
Programming Guide
OBW (27-71)
SBW (27-70)
Actual head
Setpoint
SBW (27-70)
OBW (27-71)
Danfoss A/S © 10/2019 All rights reserved.
25-27 Stage Function
Option: Function:
If the stage function is set to [0]
Disabled, parameter 25-28 Stage
Function Time is not 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 [1] Enabled by
parameter 25-27 Stage Function, and
when the variable-speed pump
runs at motor speed high limit,
parameter 4-13 Motor Speed High
Limit [RPM] or parameter 4-14 Motor
Speed High Limit [Hz], with at least 1
fixed-speed pump in the stop
position. When the programmed
value of the timer expires, a fixed-
speed pump is staged.
25-29 Destage Function
Option: Function:
The destage function ensures that
the lowest numbers of pumps are
running to save energy and to
avoid dead head water circulation
in the variable-speed pump. If the
destage function is set to [0]
Disabled, parameter 25-30 Destage
Function Time is not activated.
[0] Disabled
[1] Enabled
*
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