Danfoss VLT HVAC Series Programming Manual page 264

3 Parameter Description
25-24 SBW De-staging Delay
Range:
15 s* [0 - 3000 s]
3
25-25 OBW Time
Range:
10 s* [0 - 300 s]
25-26 Destage At No-Flow
Option:
[0] * Disabled
[1] Enabled
3-240
Function:
Immediate de-staging of a fixed speed pump is not desirable during a momentary pressure increase
in the system that exceeds the staging bandwidth (SBW). De-staging 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.
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 de-stage 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 has been 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.
Function:
The de-stage at the no-flow parameter ensures that when a no-flow situation occurs, the fixed speed
pumps will be de-staged one-by-one until the no-flow signal disappears. This requires that no-flow
detection is active. See par. 22-2*.
If De-stage at No-Flow is disabled the Cascade Controller does not change the normal behavior of
the system.
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VLT ® HVAC Drive Programming Guide