Quick Menu Water And Pumps; Deragging Function - Danfoss VLT AQUA Drive FC 202 Design Manual

Application Examples
•
Basic cascade control: Speed control of a single
pump in a multi-pump system. This is a cost-
attractive solution in, for example, booster sets.
•
Master-follower: Control up to eight adjustable
frequency drives and pumps to ensure smooth
operation of the overall pump system.

4.2.2 Quick Menu Water and Pumps

The quick menu entry water and pumps provides quick
access to the most common water and pump features of
®
the VLT AQUA Drive:
•
Special ramps (initial/final ramp, check valve
ramp)
•
Sleep mode
•
Deragging
•
Dry-run detection
•
End of curve detection
•
Flow compensation
•
Pipe fill mode for horizontal, vertical and mixed
pipe systems
•
Control performance
•
Minimum speed monitor

4.2.3 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
adjustable frequency drive starts to derag to when the
deragging finishes. When a derag is started, the adjustable
frequency drive ramps first to a stop and then an off delay
expires before the first cycle begins.
MG20N622
Design Guide
Speed
+/- Derag
Speed:
Par.: 29 -13
Par.: 29 -14
0 Hz / RPM
Figure 4.1 Derag Function
If a derag is triggered from an adjustable frequency drive-
stopped state, the first off delay is skipped. The deragging
event may consist of several cycles. One cycle consisting of
one pulse in the reverse direction followed by one pulse in
the forward direction. Deragging is considered finished
after the specified number of cycles has completed. More
specifically, on the last pulse (it will always be forward) of
the last cycle, the derag is considered finished after the
deragging run time expires (the adjustable frequency drive
is running at derag speed). In between pulses, the
adjustable frequency drive 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 three different notifications for an ongoing
deragging event:
•
•
•
Danfoss A/S © 09/2014 All rights reserved.
Derag
function
activated
Derag O 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.
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