Danfoss VLT AQUA Drive FC 202 Programming Manual page 229

Parameter Description
NOTICE
In master/slave applications, the override limit is used as
the wake-up condition. See documentation for Cascade
Controller Option MCO 101 for further information.
OBW timer (27-25)
Illustration 3.99 OBW Time
27-22 Fixed Speed Only Operating Range
Range: Function:
Size [ 0 - Enter the allowed offset from the setpoint
related par. at which a fixed speed pump is added or
*
27-21 % removed when there are no operational
] variable speed pumps. The value is a
percentage of parameter 21-12 Ext. 1
Maximum Reference. The system must be
outside this limit for the time specified in
parameter 27-23 Staging Delay or
parameter 27-24 Destaging Delay before a
cascade operation takes place.
Illustration 3.100 SBW Staging Delay
MG20OB02
Programming Guide
OBW (27-71)
SBW (27-70)
Actual head
Setpoint
SBW (27-70)
OBW (27-71)
Danfoss A/S © 05/2018 All rights reserved.
(27-24) SBW destage delay
Illustration 3.101 SBW Destaging Delay
27-23 Staging Delay
Range: Function:
15 [0 - Enter the time during which the system feedback
s 3000 s] must remain below the operating range before a
*
fixed speed pump is turned on. If the system is
operating with at least 1 variable speed pump
available, parameter 27-20 Normal Operating Range
is used. If no variable speed pumps are available,
parameter 27-22 Fixed Speed Only Operating Range
is used.
27-24 Destaging Delay
Range: Function:
15 [0 - Enter the time during which the system feedback
s 3000 s] must remain above the operating range before a
*
pump is turned off. If the system is operating
with at least 1 variable speed pump available,
parameter 27-20 Normal Operating Range is used. If
no variable speed pumps are available,
parameter 27-22 Fixed Speed Only Operating Range
is used.
27-25 Override Hold Time
Range: Function:
10 [0 - Enter the minimum time that must elapse after
s 300 s] staging or destaging before another staging or
*
destaging may take place due to the system
exceeding the value in parameter 27-21 Override
Limit. This value allows the system to stabilize after
a pump is turned on or off. If this delay is not long
enough, the transients caused by turning a pump
on or off may cause the system to add or remove
another pump unnecessarily.
27-27 Min Speed Destage Delay
Range: Function:
Size [ 0 - Enter the time that the lead pump must run
related 300 s] at minimum speed while the system
*
feedback is still inside the normal operating
band before a pump is turned off to save
energy. Energy savings are achieved by
SBW
(27-20) 3
Setpoint
SBW
(27-20)
227
3