The "relays/controls" menu
119
5.4
The "rake control" submenu
!
Note!
The "rake control" submenus is only present if "rake control" has been selected in "device
properties/operating parameters/controls".
5.4.1
Basics
In order to detect clogging of a rake, the Prosonic S measures the upstream level L1 and the
downstream leve L2. Rake clogging causes L2 to become much lower than L1. Therefore, the rake
control function evaluates either the difference L1 - L2 or the ratio L2/L1.
L00-FMU90xxx-19-00-00-yy-058
Rake clogging is indicated by a relay, which can be used, for example, to trigger a rake cleaning
device.
5.4.2
Overview
!
Note!
In the "output/calculations" and "calibrate display" menus it is possible to define that the difference
L1-L2 or the ratio L2/L1 is displayed by the analog output and/or the display.
L1
L2
Step
Parameter set or submenu Parameter
Remarks
see section
1
"relay/controls" menu
Select "rake control"
2
rake control
upstream water
Select the upstream water level signal (L1)
5.4.3
downstream water
Select the downstream water level signal (L2)
function
Select the criterion for rake clogging:
• difference: L1 - L2
• ratio: L2/L1
3
rake control
switch on point
Define the switch on point
5.4.4
switch off point
Define the switch off point
4
rake control
switch delay
Define the switch delay.
5.4.5
error handling
Define the error handling
5
relay allocation
Select the relay for rake control
5.4.6
6
relay N
(N = 1 - 6)
function
Select "rake control"
5.4.7
invert
Select if the switching delay is to be inverted (default: no)
Summary of Contents for Prosonic S FMU90
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