22-82 Work Point Calculation
Option: Function:
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 has to be determined based
on the datasheet. Looking at the
curve for the rated speed and
plotting the design pressure
(H
DESIGN
, Point C), the îš‚ow at that
pressure, Q
RATED
, can be determined.
Similarly, by plotting the design
îš‚ow (Q
DESIGN
, Point D), the pressure
H
DESIGN
at that îš‚ow can be
determined. Knowing these 2
points on the pump curve, along
with H
MIN
as described, allows the
frequency converter to calculate the
reference point B and thus to plot
the control curve, which also
includes the system design working
point A.
Set point
Control Curve
n
D
E
S
I
G
N
-
f
D
E
S
I
G
N
n
R
A
T
E
D
-
f
R
A
T
E
D
(head)H
H
RATED
Par.
22-88
Q
DESIGN
Par.
22-89
H
MIN
D
B
C
A
Q
RATED
Par.
22-90
(flow)
Q
H
DESIGN
130BA387.11
22-84/
22-87
22-83/
Par.:
Illustration 3.65 Speed at System
Design Working Point is not
Known
[0] * Disabled Work point calculation not active.
To be used if speed at design point
is known.
[1] Enabled 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:
•
Parameter 22-83 Speed at
No-Flow [RPM].
•
Parameter 22-84 Speed at
No-Flow [Hz].
•
Parameter 22-87 Pressure at
No-Flow Speed.
22-82 Work Point Calculation
Option: Function:
•
Parameter 22-88 Pressure at
Rated Speed.
•
Parameter 22-89 Flow at
Design Point.
•
Parameter 22-90 Flow at
Rated Speed.
22-83 Speed at No-Flow [RPM]
Range: Function:
Size
related*
[ 0 - par.
22-85 RPM]
Resolution 1 RPM.
Enter the speed of the motor in
RPM at which îš‚ow is 0 and
minimum pressure H
MIN
is achieved.
Alternatively, enter the speed in Hz
in parameter 22-84 Speed at No-Flow
[Hz]. If parameter 0-02 Motor Speed
Unit is set to RPM,
parameter 22-85 Speed at Design
Point [RPM] should also be used.
Closing the valves and reducing the
speed until minimum pressure H
MIN
is achieved determines this value.
22-84 Speed at No-Flow [Hz]
Range: Function:
Size
related*
[ 0 - par.
22-86 Hz]
Resolution 0.033 Hz.
Enter the motor speed in Hz at
which îš‚ow has eîš„ectively stopped
and minimum pressure H
MIN
is
achieved. Alternatively, enter the
speed in RPM in
parameter 22-83 Speed at No-Flow
[RPM]. If parameter 0-02 Motor
Speed Unit is set to Hz,
parameter 22-86 Speed at Design
Point [Hz] should also be used.
Closing the valves and reducing the
speed until minimum pressure H
MIN
is achieved determines this value.
Parameter Descriptions Programming Guide
M0010001 Danfoss A/S © 10/2019 All rights reserved. 211
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