25-23 SBW Staging Delay
Range:
Function:
15
s
*
[0 -
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
programmed. If the pressure increases within the
SBW before the timer has elapsed, the timer is
reset.
Illustration 3.72 SBW Staging Delay
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 increases in
the system that exceeds the staging bandwidth
(SBW). Destaging is delayed by the length of time
programmed. If the pressure decreases within the
SBW before the timer has elapsed, the timer is
reset.
175ZA671.11
(27-24) SBW destage delay
SBW
SBW
Setpoint
(27-20)
(27-20)
Illustration 3.73 SBW Destaging Delay
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
25-25 OBW Time
Range:
Function:
prevent staging until the system pressure has
stabilised and normal control established. Set the
timer to a value that allows the system to stabilise
after staging. The 10 s factory setting is appropriate
in most applications. In highly dynamic systems, a
shorter time may be wanted.
Setpoint
SBW (27-70)
OBW (27-71)
SBW (27-70)
OBW (27-71)
Actual head
OBW timer (27-25)
130BA370.11
Illustration 3.74 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 behaviour of the
system.
[0]
*
Disabled
[1]
Enabled
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
Parameter Descriptions
Programming Guide
MG11CE02
Danfoss A/S © 03/2015 All rights reserved.
193
3
3