Danfoss VLT AQUA Drive FC 202 Programming Manual page 162

Parameter Description
NOTICE
Not visible when running in cascade.
H (head)
3 3
Control Curve
Illustration 3.62 Square-linear Curve Approximation
22-82 Work Point Calculation
Option:
160
Function:
Example 1:
H
(head)
H
A
DESIGN
Set Point
H
MIN
Par.:
22-83/
Control Curve
22-84/
22-87
Q
(flow)
Illustration 3.63 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 point and the
DESIGN
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
MIN
achieved allows the speed at the no flow point to
be identified.
Adjustment of parameter 22-81 Square-linear Curve
Approximation 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
Danfoss A/S © Rev. 2014-01-21 All rights reserved.
Programming Guide
22-82 Work Point Calculation
Option:
Q ( ow)
[0] Disabled Work Point Calculation not active. To be used if
[1] Enabled Work Point Calculation is active. Enabling this
22-83 Speed at No-Flow [RPM]
Range:
Size
related
*
has been
Function:
Q can be determined. Similarly, by plotting the
RATED
design flow (Q , Point D). The pressure H
DESIGN
at that flow can be determined. Knowing these 2
points on the pump curve, along with H
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.
H (head)
H
RATED D
Par.
B
A
22-88
C
H
DESIGN
Set point
H
MIN
Par.:
22-83/
Control Curve
22-84/
22-87
Q Q
DESIGN RATED
Par.
Par.
22-90
22-89
Illustration 3.64 Speed at System Design
Working Point is not Known
speed at design point is known.
parameter allows the calculation of the unknown
System Design Working Point at 50/60 Hz speed,
from the input data set in parameter 22-83 Speed at
No-Flow [RPM] parameter 22-84 Speed at No-Flow
[Hz], parameter 22-87 Pressure at No-Flow Speed,
parameter 22-88 Pressure at Rated Speed,
parameter 22-89 Flow at Design Point and
parameter 22-90 Flow at Rated Speed.
Function:
[ 0 - Resolution 1 RPM.
par. The speed of the motor at which flow Is
22-85 zero and minimum pressure H
RPM] should be entered here in RPM. Alterna-
tively, the speed in Hz can be entered in
parameter 22-84 Speed at No-Flow [Hz]. If it
has been decided to use RPM in
parameter 0-02 Motor Speed Unit then
parameter 22-85 Speed at Design Point [RPM]
should also be used. Closing the valves and
reducing the speed until minimum pressure
H is achieved determines this value.
MIN
DESIGN
as
MIN
Q
(flow)
is achieved
MIN
MG20O702