Danfoss VLT AQUA Drive FC 202 Programming Manual page 161

Parameter Description
22-77 Minimum Run Time
Range: Function:
0 s [ 0 - par. Sets the time desired as minimum run time
*
22-76 s] after a normal start command (start/jog/freeze).
Any normal stop command is disregarded until
the set time has expired. The timer starts
counting following a normal start command
(start/jog/freeze).
The timer is overridden by a coast (inverse) or
an external interlock command.
NOTICE
Does not work in cascade mode.
22-78 Minimum Run Time Override
Option:
[0] Disabled
[1] Enabled
22-79 Minimum Run Time Override Value
Range:
0 ProcessCtrlUnit [-999999.999 - 999999.999
*
ProcessCtrlUnit]
3.19.8 22-8* Flow Compensation
Sometimes it is not possible for a pressure transducer to
be placed at a remote point in the system and it can only
be located close to the fan/pump outlet. Flow compen-
Parameter used
Parameter 22-80 Flow Compensation
Parameter 22-81 Square-linear Curve Approximation
Parameter 22-82 Work Point Calculation
Parameter 22-83 Speed at No-Flow [RPM]/parameter 22-84 Speed at No-
Flow [Hz]
Parameter 22-85 Speed at Design Point [RPM]/parameter 22-86 Speed at
Design Point [Hz]
Parameter 22-87 Pressure at No-Flow Speed
Parameter 22-88 Pressure at Rated Speed
Parameter 22-89 Flow at Design Point
Parameter 22-90 Flow at Rated Speed
Table 3.22 Speed at Design Point Known/Unknown
22-80 Flow Compensation
Option: Function:
[0] Disabled Set-Point compensation not active.
[1] Enabled Set-Point compensation is active. Enabling this
parameter allows the Flow Compensated Setpoint
operation.
MG20O702
Programming Guide
sation operates by adjusting the set-point according to the
output frequency, which is almost proportional to flow,
thus compensating for higher losses at higher flow rates.
H
(PI) operation of the frequency converter and is set as for
closed loop operation without flow compensation.
Function:
Function:
There are 2 methods which can be employed, depending
upon whether or not the Speed at System design Working
Point is known.
100 %
Danfoss A/S © Rev. 2014-01-21 All rights reserved.
(Required pressure) is the setpoint for closed loop
DESIGN
Illustration 3.61 Flow Compensation Setup
Speed at Design Point
KNOWN
+
+
+
+
+
+
-
-
-
22-81 Square-linear Curve Approximation
Range: Function:
[0 - 100 %] Example 1:
*
Adjustment of this parameter allows the
shape of the control curve to be adjusted.
0 = Linear
100% = Ideal shape (theoretical).
Speed at Design Point
UNKNOWN
+
+
+
+
-
+
+
+
+
159
3 3