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.
Setpoint
SBW (27-70)
OBW (27-71)
SBW (27-70)
OBW (27-71)
Actual head
OBW timer (27-25)
130BA370.11
Illustration 3.99 OBW Time
27-22 Fixed Speed Only Operating Range
Range: Function:
Size
related*
[ 0 -
par.
27-21 %
]
Enter the allowed oset from the setpoint
at which a xed speed pump is added or
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 specied in
parameter 27-23 Staging Delay or
parameter 27-24 Destaging Delay before a
cascade operation takes place.
Illustration 3.100 SBW Staging Delay
175ZA671.11
(27-24) SBW destage delay
SBW
SBW
Setpoint
(27-20)
(27-20)
Illustration 3.101 SBW Destaging Delay
27-23 Staging Delay
Range: Function:
15
s*
[0 -
3000 s]
Enter the time during which the system feedback
must remain below the operating range before a
xed 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
s*
[0 -
3000 s]
Enter the time during which the system feedback
must remain above the operating range before a
pump is turned o. 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
s*
[0 -
300 s]
Enter the minimum time that must elapse after
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 o. If this delay is not long
enough, the transients caused by turning a pump
on or o may cause the system to add or remove
another pump unnecessarily.
27-27 Min Speed Destage Delay
Range: Function:
Size
related*
[ 0 -
300 s]
Enter the time that the lead pump must run
at minimum speed while the system
feedback is still inside the normal operating
band before a pump is turned o to save
energy. Energy savings are achieved by
Parameter Description Programming Guide
MG20OB02 Danfoss A/S © 05/2018 All rights reserved. 227
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