After a start command, fill-mode operation begins when
the adjustable frequency drive reaches minimum frequency
- set in
parameter 201 Output frequency low limit, f
MIN
.
The filled setpoint is a setpoint limit. When minimum
speed is reached, the pressure feedback is evaluated, and
the adjustable frequency drive begins to ramp to the filled-
pressure setpoint at the rate set in parameter 485 fill rate.
The fill rate is dimensioned in units/S. The units are the
units selected in
parameter 416 Process units
.
When the pressure feedback equals the filled setpoint, the
control transitions to the operating setpoint (Setpoint 1-4,
parameter 215-218
) and continues operation in standard
(normal) closed loop mode.
The value to use for the filled setpoint, can be determined
by:
1.
Press DISPLAY MODE on the LCP to display
FEEDBACK 1.
NOTICE
Select the units in
parameter 416 Process units
before this
step.
2.
Operate the frequency converter in HAND mode
and slowly advance the speed to fill the pipe
while being careful not to create a water
hammer.
3.
An observer at the end of the pipe must be able
to report when the pipe is filled.
4.
At that instant, stop the motor, and observe the
value of pressure feedback (have the LCP display
set to observe the feedback before starting).
5.
The value of feedback in step 4 is the value to
use in
parameter 486 filled setpoint
.
The value to set in
parameter 485 fill rate
can be supplied
by the system engineer from proper calculation or from
experience, or it can be determined experimentally by
performing numerous fill-mode sequences and either
increasing or decreasing the value of this parameter to
obtain the fastest fill without causing a water hammer.
The fill mode is also beneficial when bringing the motor to
a stop as it prevents sudden changes in pressure and flow
which could also cause a water hammer.
Illustration 4.21 Fill Mode Example
485
Fill Rate
Value:
OFF/000000.001 - 999999.999 (units/s) -
OFF
Function:
Establishes the rate at which the pipe is filled.
Description of choice:
The dimension of this parameter is units/S. The units is the
value selected in
parameter 416 Process units
. As an
example, the units could be Bar, or MPa, or PSI, etc. If
[4]
Bar
is the selected unit in
parameter 416 Process units
, the
number set in this
parameter 485
would be dimensioned
as Bar/S. Changes to this parameter can be made in steps
of .001 units.
486
Filled Setpoint
Value:
Parameter 414 - Parameter 205 -
Parameter 414
Function:
The value set in this parameter corresponds to the
pressure that exists at the pressure sensor when the pipe
is filled.
Description of choice:
The units of this parameter correspond to the units
selected in
Parameter 416 Process units
. The minimum value
of this parameter is Fb
min
(
parameter 414 Minimum
feedback FB
MIN
). The maximum value for this parameter is
Ref
max
(
parameter 205 Maximum reference, Ref
MAX
). The
setpoint can be changed in .01 steps.
Programming
Design Guide
MG27E402
Danfoss A/S © Rev. May/2014 All rights reserved.
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