Danfoss VLT AQUA Drive FC 202 Programming Manual page 238

Parameter Description
29-04 Pipe Fill Rate
Range:
0.001
ProcessCtrlUnit
3 3
29-05 Filled Setpoint
Range:
0
ProcessCtrlUnit
29-06 No-Flow Disable Timer
Range:
0 s [0 - 3600 s]
*
29-07 Filled setpoint delay
Range:
0 s [0 - 10 s] Select the delay before the frequency converter
*
3.25.2 29-1* Deragging Function
The purpose of the deragging feature is to free the pump
blade of debris in waste water applications so that the
pump operates normally.
A deragging event is defined as the time when the
frequency converter starts to derag to when the deragging
finishes. When a derag is started, the frequency converter
ramps first to a stop and then an off delay expires before
the first cycle begins.
236
Function:
[0.001 - Specifies the fill rate in units
999999.999 using the PI controller. Fill
*
ProcessCtrlUnit] rate units are feedback units.
This function is used for
filling up vertical pipe
systems, but is active when
the filling time has expired,
until the pipe fill setpoint set
in parameter 29-05 Filled
Setpoint is reached.
Function:
[-999999.999 - Specifies the filled
999999.999 setpoint at which the pipe
*
ProcessCtrlUnit] fill function is disabled
and the PID controller
takes control. This
function can be used both
for horizontal and vertical
pipe systems.
Function:
Function:
considers the filled setpoint to be reached if a
fill rate in units per second is used.
Danfoss A/S © 05/2018 All rights reserved.
®
VLT AQUA Drive FC 202
Speed
+/- Derag
speed:
Par.: 29 -13
Par.: 29 -14
0 Hz/RPM
Illustration 3.112 Derag Function
If a derag is triggered from a frequency converter-stopped
state, the first off delay is skipped. The deragging event
may consist of several cycles: one cycle consisting of 1
pulse in the reverse direction followed by 1 pulse in the
forward direction. Deragging is considered finished after
the specified number of cycles have completed. More
specifically, on the last pulse (it is always forward) of the
last cycle, the derag is considered finished after the
deragging run-time expires (the frequency converter is
running at derag speed). In between pulses, the frequency
converter output coasts for a specified off-delay time to let
debris in the pump settle.
NOTICE
Do not enable deragging if the pump cannot operate in
reverse direction.
There are 3 different notifications for an ongoing
deragging event:
•
•
•
Depending on the application and the purpose of using it,
this feature can be used as a preventive or reactive
measure and can be triggered/started in the following
ways:
Derag
function
activated
Derag off delay:
Par. 29 -15
Deragging run-time : Par . 29-12
1 Cycle
Number of cycles : Par . 29 -10
Status in the LCP: Auto Remote Derag.
A bit in the extended status word (bit 23, 80 0000
hex).
A digital output can be configured to reflect the
active deragging status.
MG20OB02