Danfoss VLT AQUA Drive FC 200 Programming Manual page 159

Parameter Description
Parameter used
22-80 Flow Compensation
22-81 Square-linear Curve Approximation
22-82 Work Point Calculation
22-83 Speed at No-Flow [RPM]/22-84 Speed at No-Flow [Hz]
22-85 Speed at Design Point [RPM]/22-86 Speed at Design Point [Hz]
22-87 Pressure at No-Flow Speed
22-88 Pressure at Rated Speed
22-89 Flow at Design Point
22-90 Flow at Rated Speed
Table 3.27 Speed at Design Point Known/Unknown
22-80 Flow Compensation
Option: Function:
[0] Disabled Setpoint compensation not active.
[1] Enabled Setpoint compensation is active. Enabling this
parameter allows the Flow Compensated Setpoint
operation.
22-81 Square-linear Curve Approximation
Range:
100 % [0 - 100 %]
*
NOTICE!
Not visible when running in cascade.
H (head)
Control Curve
Figure 3.56
®
VLT AQUA Drive Programming Guide
Function:
Q ( ow)
®
MG20O622 - VLT is a registered Danfoss trademark
Speed at Design Point
KNOWN
+
+
+
+
+
+
-
-
-
22-82 Work Point Calculation
Option: Function:
Example 1:
H(head)
HDESIGNSetpoint
HMIN
P22-83/
P22-84
Control Curve
P22-87
Figure 3.57 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
Q point allows us to find point A, which is the
DESIGN
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
achieved allows the speed at the no-flow point to
be identified.
Adjustment of 22-81 Square-linear Curve Approxi-
mation 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 , Point C) the flow at that pressure
DESIGN
Q can be determined. Similarly, by plotting the
RATED
design flow (Q
DESIGN
at that flow can be determined. Knowing these
two points on the pump curve, along with H
described above, allows the adjustable frequency
Speed at Design Point
UNKNOWN
+
+
+
+
-
+
+
+
+
A
point and the
DESIGN
has been
MIN
, Point D). The pressure H
DESIGN
MIN
3-133
3 3