Operating instructions

22-80 Flow Compensation
Option: Function:
[0] * Disabled [0] Disabled: Set-Point compensation not active.
[1] Enabled [1] Enabled:Set-Point compensation is active.
Enabling this parameter allows the Flow Compen-
sated Setpoint operation.
22-81 Square-linear Curve Approximation
Range: Function:
100 % * [0 - 100 %] Example 1:
Adjustment of this parameter allows the
shape of the control curve to be adjusted.
0 = Linear
100% = Ideal shape (theoretical).
NOTE
Not visible when running in cascade.
22-82 Work Point Calculation
Option: Function:
Example 1: Speed at System Design Working Point is
known:
From the data sheet showing characteristics for the
specific equipment at different speeds, simply
reading across from the H
DESIGN
point and the
Q
DESIGN
point allows us to find point A, which is the
System Design Working Point. The pump character-
istics at this point should be identified and the
associated speed programmed. Closing the valves
and adjusting the speed until H
MIN
has been
22-82 Work Point Calculation
Option: Function:
achieved allows the speed at the no flow point to be
identified.
Adjustment of par. 22-81 Square-linear Curve Approx-
imation then allows the shape of the control curve
to be adjusted infinitely.
Example 2:
Speed at System Design Working Point is not
known: Where the Speed at System Design Working
Point is unknown, another reference point on the
control curve needs to be determined by means of
the data sheet. By looking at the curve for the rated
speed and plotting the design pressure (H
DESIGN
,
Point C) the flow at that pressure Q
RATED
can be
determined. Similarly, by plotting the design flow
(Q
DESIGN
, Point D). the pressure H
D
at that flow can be
determined. Knowing these two points on the pump
curve, along with H
MIN
as described above, allows
the frequency converter to calculate the reference
point B and thus to plot the control curve which will
also include the System design Working Point A.
[0]
*
Disabled Disabled [0]: Work Point Calculation not active. To be
used if speed at design point is known (see table
above).
[1] Enabled Enabled [1] : Work Point Calculation is active.
Enabling this parameter allows the calculation of the
unknown System Design Working Point at 50/60 Hz
speed, from the input data set in par. 22-83 Speed at
No-Flow [RPM] par. 22-84 Speed at No-Flow [Hz],
par. 22-87 Pressure at No-Flow Speed,
par. 22-88 Pressure at Rated Speed, par. 22-89 Flow at
Design Point and par. 22-90 Flow at Rated Speed.
Parameter Description
VLT
®
HVAC Drive Programming Guide
MG.11.CA.02 - VLT
®
is a registered Danfoss trademark 149
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