Danfoss VLT FC 100 Series Programming Manual page 213

®
VLT HVAC Drive Programming Guide
25-25 OBW Time
Range:
*
10 sec. [0 – 300 sec. ]
25-26 Destage at No-Flow
Option:
*
Disabled
[0]
[1] Enabled
25-27 Stage Function
Option:
[0] Disabled
*
Enabled
[1]
25-28 Stage Function Time
Range:
*
15 sec. [0 – 300 sec.]
25-29 Destage Function
Option:
Function:
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 ap-
propriate in most applications. In highly dynamic systems, a shorter time may be desirable.
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
par. 22-2*.
If Destage at No-Flow is disabled the cascade controller does not change the normal behavior of the system.
Function:
If the Stage Function is set to Disabled
Function:
The Stage Function Time is programmed to avoid frequent staging of the fixed speed pumps. The Stage Function
Enabled Stage Feature
Time starts if it is [1] by
Motor Speed High Limit
, par. 4-13 or 4-14, 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.
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
Timer , par. 25-30, will not be activated.
MG.11.C5.02 - VLT ® is a registered Danfoss trademark
[0], par. 25-28, Stage Timer , will not be activated.
, par. 25-27, and when the variable speed pump is running at
3. Parameter Description
Disabled [0], the Destage
213
3