Danfoss VLT AQUA Drive FC 202 Operating Instructions Manual page 90

How to programme the freque...
H (head)
Control Curve
Illustration 6.23 Square-linear Curve Approximation
6 6
22-82 Work Point Calculation
Option:
88
Function:
Example 1
H
(head)
H
A
DESIGN
Set Point
H
MIN
Par.:
22-83/
Control Curve
22-84/
22-87
Q
(flow)
Illustration 6.24 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 finding 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
DESIGN
pressure, Q , can be determined. Similarly, by
RATED
plotting the design flow (Q , Point D). The
DESIGN
pressure H at that flow can be determined.
DESIGN
Knowing these 2 points on the pump curve, along
Danfoss A/S © Rev. 06/2014 All rights reserved.
Operating Instructions
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
22-84 Speed at No-Flow [Hz]
Range:
Size
related
*
has been
Function:
with H as described above, allows the
MIN
frequency converter to calculate the reference
point B and thus to plot the control curve which
also includes 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 6.25 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, 22-89 Flow
at Design Point and parameter 22-90 Flow at Rated
Speed.
Function:
[ 0 - Resolution 0.033 Hz.
par.
Enter the motor speed in Hz at which flow
22-86
has effectively stopped and minimum
Hz]
pressure H is achieved. Alternatively, the
MIN
speed in RPM can be entered in
parameter 22-83 Speed at No-Flow [RPM]. If it
has been decided to use Hz in 0-02 Motor
Speed Unit, parameter 22-86 Speed at Design
Point [Hz] should also be used. Closing the
valves and reducing the speed until
minimum pressure H
MIN
determines this value.
Q
(flow)
is achieved
MG20Y202