Illustration 5.1
175ZA671.11
(27-24) SBW destage delay
SBW
SBW
Setpoint
(27-20)
(27-20)
Illustration 5.2
27-21 Override Limit
Range:
Function:
100
%
*
[ 0 -
100
%]
Override Limit is the allowed offset from the set-
point before a pump will immediately be added
or removed (for instance in case of a fire tab is
switched on). Normal Operating Range includes a
delay that limits the system response to
transients. This makes the system respond too
slowly to large demand changes. The override
limit causes the frequency converter to respond
immediately. The value is entered as a % of Max
Reference (
21-12 Ext. 1 Maximum Reference
).
Override operation may be disabled by setting
this parameter to 100%.
NOTICE
In master-follower applications the override limit is used
as wake-up condition. See
6.1 Master/Follower
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 5.3
27-22 Fixed Speed Only Operating Range
Range:
Function:
Size
related
*
[ 0 -
par.
27-21 %]
Fixed Speed Only Operating Range is the
allowed offset from the set-point before a
pump may be added or removed when
there are no operational variable speed
pumps. The system must be outside this
limit for the time specified in
27-23 Staging
Delay
or
27-24 Destaging Delay
before a
cascade operation may take place. The
value is entered as a % of Max Reference.
When there are no operational variable
speed pumps, the system will try to
maintain control with the remaining fixed
speed pumps.
Illustration 5.4
Parameter Descriptions
VLT
®
AQUA Drive MCO 101/MCO 102
MI38C402 - VLT
®
is a registered Danfoss trademark
27
5
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